[ie/youtube] SABR Downloader

2025-06-27 17:08:32 +00:00 · 2025-06-21 11:15:25 +12:00 · 2025-06-21 11:15:25 +12:00 · c898d5f738
commit c898d5f738
parent 73bf102116
48 changed files with 4069 additions and 274 deletions
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@ -208,7 +208,7 @@ jobs:
            python3.9 -m pip install -U pip wheel 'setuptools>=71.0.2'
            # XXX: Keep this in sync with pyproject.toml (it can't be accessed at this stage) and exclude secretstorage
            python3.9 -m pip install -U Pyinstaller mutagen pycryptodomex brotli certifi cffi \
-              'requests>=2.32.2,<3' 'urllib3>=1.26.17,<3' 'websockets>=13.0'
+              'requests>=2.32.2,<3' 'urllib3>=1.26.17,<3' 'websockets>=13.0' 'protobug==0.3.0'

          run: |
            cd repo
--- a/README.md
+++ b/README.md
@ -212,6 +212,7 @@ ### Metadata

 ### Misc

+* [**protobug**](https://github.com/yt-dlp/protobug)\* - Protobuf library, for serializing and deserializing protobuf data. Licensed under [Unlicense](https://github.com/yt-dlp/protobug/blob/main/LICENSE)
 * [**pycryptodomex**](https://github.com/Legrandin/pycryptodome)\* - For decrypting AES-128 HLS streams and various other data. Licensed under [BSD-2-Clause](https://github.com/Legrandin/pycryptodome/blob/master/LICENSE.rst)
 * [**phantomjs**](https://github.com/ariya/phantomjs) - Used in extractors where javascript needs to be run. Licensed under [BSD-3-Clause](https://github.com/ariya/phantomjs/blob/master/LICENSE.BSD)
 * [**secretstorage**](https://github.com/mitya57/secretstorage)\* - For `--cookies-from-browser` to access the **Gnome** keyring while decrypting cookies of **Chromium**-based browsers on **Linux**. Licensed under [BSD-3-Clause](https://github.com/mitya57/secretstorage/blob/master/LICENSE)
@ -1808,6 +1809,7 @@ #### youtube
 * `innertube_host`: Innertube API host to use for all API requests; e.g. `studio.youtube.com`, `youtubei.googleapis.com`. Note that cookies exported from one subdomain will not work on others
 * `innertube_key`: Innertube API key to use for all API requests. By default, no API key is used
 * `raise_incomplete_data`: `Incomplete Data Received` raises an error instead of reporting a warning
+* `sabr_log_level`: Set the log level of the SABR downloader. One of `TRACE`, `DEBUG` or `INFO` (default)
 * `data_sync_id`: Overrides the account Data Sync ID used in Innertube API requests. This may be needed if you are using an account with `youtube:player_skip=webpage,configs` or `youtubetab:skip=webpage`
 * `visitor_data`: Overrides the Visitor Data used in Innertube API requests. This should be used with `player_skip=webpage,configs` and without cookies. Note: this may have adverse effects if used improperly. If a session from a browser is wanted, you should pass cookies instead (which contain the Visitor ID)
 * `po_token`:  Proof of Origin (PO) Token(s) to use. Comma seperated list of PO Tokens in the format `CLIENT.CONTEXT+PO_TOKEN`, e.g. `youtube:po_token=web.gvs+XXX,web.player=XXX,web_safari.gvs+YYY`. Context can be any of `gvs` (Google Video Server URLs), `player` (Innertube player request) or `subs` (Subtitles)
--- a/pyproject.toml
+++ b/pyproject.toml
@ -53,6 +53,7 @@ default = [
    "requests>=2.32.2,<3",
    "urllib3>=1.26.17,<3",
    "websockets>=13.0",
+    "protobug==0.3.0",
 ]
 curl-cffi = [
    "curl-cffi>=0.5.10,!=0.6.*,!=0.7.*,!=0.8.*,!=0.9.*,<0.11; implementation_name=='cpython'",
--- a/test/test_sabr/test_ump.py
+++ b/test/test_sabr/test_ump.py
@ -0,0 +1,102 @@
+import io
+import pytest
+
+from yt_dlp.extractor.youtube._streaming.ump import varint_size, read_varint, UMPDecoder, UMPPartId
+
+
+@pytest.mark.parametrize('data, expected', [
+    (0x01, 1),
+    (0x4F, 1),
+    (0x80, 2),
+    (0xBF, 2),
+    (0xC0, 3),
+    (0xDF, 3),
+    (0xE0, 4),
+    (0xEF, 4),
+    (0xF0, 5),
+    (0xFF, 5),
+])
+def test_varint_size(data, expected):
+    assert varint_size(data) == expected
+
+
+@pytest.mark.parametrize('data, expected', [
+    # 1 byte long varint
+    (b'\x01', 1),
+    (b'\x4F', 79),
+    # 2 byte long varint
+    (b'\x80\x01', 64),
+    (b'\x8A\x7F', 8138),
+    (b'\xBF\x7F', 8191),
+    # 3 byte long varint
+    (b'\xC0\x80\x01', 12288),
+    (b'\xDF\x7F\xFF', 2093055),
+    # 4 byte long varint
+    (b'\xE0\x80\x80\x01', 1574912),
+    (b'\xEF\x7F\xFF\xFF', 268433407),
+    # 5 byte long varint
+    (b'\xF0\x80\x80\x80\x01', 25198720),
+    (b'\xFF\x7F\xFF\xFF\xFF', 4294967167),
+],
+)
+def test_readvarint(data, expected):
+    assert read_varint(io.BytesIO(data)) == expected
+
+
+class TestUMPDecoder:
+    EXAMPLE_PART_DATA = [
+        {
+            # Part 1: Part type of 20, part size of 127
+            'part_type_bytes': b'\x14',
+            'part_size_bytes': b'\x7F',
+            'part_data_bytes': b'\x01' * 127,
+            'part_id': UMPPartId.MEDIA_HEADER,
+            'part_size': 127,
+        },
+        # Part 2, Part type of 4294967295, part size of 0
+        {
+            'part_type_bytes': b'\xFF\xFF\xFF\xFF\xFF',
+            'part_size_bytes': b'\x00',
+            'part_data_bytes': b'',
+            'part_id': UMPPartId.UNKNOWN,
+            'part_size': 0,
+        },
+        # Part 3: Part type of 21, part size of 1574912
+        {
+            'part_type_bytes': b'\x15',
+            'part_size_bytes': b'\xE0\x80\x80\x01',
+            'part_data_bytes': b'\x01' * 1574912,
+            'part_id': UMPPartId.MEDIA,
+            'part_size': 1574912,
+        },
+    ]
+
+    COMBINED_PART_DATA = b''.join(part['part_type_bytes'] + part['part_size_bytes'] + part['part_data_bytes'] for part in EXAMPLE_PART_DATA)
+
+    def test_iter_parts(self):
+        # Create a mock file-like object
+        mock_file = io.BytesIO(self.COMBINED_PART_DATA)
+
+        # Create an instance of UMPDecoder with the mock file
+        decoder = UMPDecoder(mock_file)
+
+        # Iterate over the parts and check the values
+        for idx, part in enumerate(decoder.iter_parts()):
+            assert part.part_id == self.EXAMPLE_PART_DATA[idx]['part_id']
+            assert part.size == self.EXAMPLE_PART_DATA[idx]['part_size']
+            assert part.data.read() == self.EXAMPLE_PART_DATA[idx]['part_data_bytes']
+
+        assert mock_file.closed
+
+    def test_unexpected_eof(self):
+        # Unexpected bytes at the end of the file
+        mock_file = io.BytesIO(self.COMBINED_PART_DATA + b'\x00')
+        decoder = UMPDecoder(mock_file)
+
+        # Iterate over the parts and check the values
+        with pytest.raises(EOFError, match='Unexpected EOF while reading part size'):
+            for idx, part in enumerate(decoder.iter_parts()):
+                assert part.part_id == self.EXAMPLE_PART_DATA[idx]['part_id']
+                part.data.read()
+
+        assert mock_file.closed
--- a/test/test_sabr/test_utils.py
+++ b/test/test_sabr/test_utils.py
@ -0,0 +1,23 @@
+import pytest
+from yt_dlp.extractor.youtube._streaming.sabr.utils import ticks_to_ms, broadcast_id_from_url
+
+
+@pytest.mark.parametrize(
+    'ticks, timescale, expected_ms',
+    [
+        (1000, 1000, 1000),
+        (5000, 10000, 500),
+        (234234, 44100, 5312),
+        (1, 1, 1000),
+        (None, 1000, None),
+        (1000, None, None),
+        (None, None, None),
+    ],
+)
+def test_ticks_to_ms(ticks, timescale, expected_ms):
+    assert ticks_to_ms(ticks, timescale) == expected_ms
+
+
+def test_broadcast_id_from_url():
+    assert broadcast_id_from_url('https://example.com/path?other=param&id=example.1~243&other2=param2') == 'example.1~243'
+    assert broadcast_id_from_url('https://example.com/path?other=param&other2=param2') is None
--- a/yt_dlp/__pyinstaller/hook-yt_dlp.py
+++ b/yt_dlp/__pyinstaller/hook-yt_dlp.py
@ -25,7 +25,7 @@ def get_hidden_imports():
    for module in ('websockets', 'requests', 'urllib3'):
        yield from collect_submodules(module)
    # These are auto-detected, but explicitly add them just in case
-    yield from ('mutagen', 'brotli', 'certifi', 'secretstorage', 'curl_cffi')
+    yield from ('mutagen', 'brotli', 'certifi', 'secretstorage', 'curl_cffi', 'protobug')


 hiddenimports = list(get_hidden_imports())
--- a/yt_dlp/dependencies/init.py
+++ b/yt_dlp/dependencies/init.py
@ -79,6 +79,11 @@
 except ImportError:
    curl_cffi = None

+try:
+    import protobug
+except ImportError:
+    protobug = None
+
 from . import Cryptodome

 all_dependencies = {k: v for k, v in globals().items() if not k.startswith('_')}
--- a/yt_dlp/downloader/init.py
+++ b/yt_dlp/downloader/init.py
@ -15,6 +15,10 @@ def get_suitable_downloader(info_dict, params={}, default=NO_DEFAULT, protocol=N
          and not (to_stdout and len(protocols) > 1)
          and set(protocols) == {'http_dash_segments_generator'}):
        return DashSegmentsFD
+    elif SabrFD is not None and set(downloaders) == {SabrFD} and SabrFD.can_download(info_copy):
+        # NOTE: there may be one or more SABR downloaders for this info_dict,
+        # as SABR can download multiple formats at once.
+        return SabrFD
    elif len(downloaders) == 1:
        return downloaders[0]
    return None
@ -36,6 +40,7 @@ def get_suitable_downloader(info_dict, params={}, default=NO_DEFAULT, protocol=N
 from .websocket import WebSocketFragmentFD
 from .youtube_live_chat import YoutubeLiveChatFD
 from .bunnycdn import BunnyCdnFD
+from .sabr import SabrFD

 PROTOCOL_MAP = {
    'rtmp': RtmpFD,
@ -56,6 +61,7 @@ def get_suitable_downloader(info_dict, params={}, default=NO_DEFAULT, protocol=N
    'youtube_live_chat': YoutubeLiveChatFD,
    'youtube_live_chat_replay': YoutubeLiveChatFD,
    'bunnycdn': BunnyCdnFD,
+    'sabr': SabrFD,
 }


--- a/yt_dlp/downloader/sabr/init.py
+++ b/yt_dlp/downloader/sabr/init.py
@ -0,0 +1,24 @@
+from __future__ import annotations
+
+from yt_dlp.dependencies import protobug
+from yt_dlp.utils import DownloadError
+from yt_dlp.downloader import FileDownloader
+
+if not protobug:
+    class SabrFD(FileDownloader):
+
+        @classmethod
+        def can_download(cls, info_dict):
+            is_sabr = (
+                info_dict.get('requested_formats')
+                and all(
+                    format_info.get('protocol') == 'sabr'
+                    for format_info in info_dict['requested_formats']))
+
+            if is_sabr:
+                raise DownloadError('SABRFD requires protobug to be installed')
+
+            return is_sabr
+
+else:
+    from ._fd import SabrFD  # noqa: F401
--- a/yt_dlp/downloader/sabr/_fd.py
+++ b/yt_dlp/downloader/sabr/_fd.py
@ -0,0 +1,330 @@
+from __future__ import annotations
+import collections
+import itertools
+
+from yt_dlp.networking.exceptions import TransportError, HTTPError
+from yt_dlp.utils import traverse_obj, int_or_none, DownloadError, join_nonempty
+from yt_dlp.downloader import FileDownloader
+
+from ._writer import SabrFDFormatWriter
+from ._logger import create_sabrfd_logger
+
+from yt_dlp.extractor.youtube._streaming.sabr.part import (
+    MediaSegmentEndSabrPart,
+    MediaSegmentDataSabrPart,
+    MediaSegmentInitSabrPart,
+    PoTokenStatusSabrPart,
+    RefreshPlayerResponseSabrPart,
+    MediaSeekSabrPart,
+    FormatInitializedSabrPart,
+)
+from yt_dlp.extractor.youtube._streaming.sabr.stream import SabrStream
+from yt_dlp.extractor.youtube._streaming.sabr.models import ConsumedRange, AudioSelector, VideoSelector, CaptionSelector
+from yt_dlp.extractor.youtube._streaming.sabr.exceptions import SabrStreamError
+from yt_dlp.extractor.youtube._proto.innertube import ClientInfo, ClientName
+from yt_dlp.extractor.youtube._proto.videostreaming import FormatId
+
+
+class SabrFD(FileDownloader):
+
+    @classmethod
+    def can_download(cls, info_dict):
+        return (
+            info_dict.get('requested_formats')
+            and all(
+                format_info.get('protocol') == 'sabr'
+                for format_info in info_dict['requested_formats']))
+
+    def _group_formats_by_client(self, filename, info_dict):
+        format_groups = collections.defaultdict(dict, {})
+        requested_formats = info_dict.get('requested_formats') or [info_dict]
+
+        for _idx, f in enumerate(requested_formats):
+            sabr_config = f.get('_sabr_config')
+            client_name = sabr_config.get('client_name')
+            client_info = sabr_config.get('client_info')
+            server_abr_streaming_url = f.get('url')
+            video_playback_ustreamer_config = sabr_config.get('video_playback_ustreamer_config')
+
+            if not video_playback_ustreamer_config:
+                raise DownloadError('Video playback ustreamer config not found')
+
+            sabr_format_group_config = format_groups.get(client_name)
+
+            if not sabr_format_group_config:
+                sabr_format_group_config = format_groups[client_name] = {
+                    'server_abr_streaming_url': server_abr_streaming_url,
+                    'video_playback_ustreamer_config': video_playback_ustreamer_config,
+                    'formats': [],
+                    'initial_po_token': sabr_config.get('po_token'),
+                    'fetch_po_token_fn': fn if callable(fn := sabr_config.get('fetch_po_token_fn')) else None,
+                    'reload_config_fn': fn if callable(fn := sabr_config.get('reload_config_fn')) else None,
+                    'live_status': sabr_config.get('live_status'),
+                    'video_id': sabr_config.get('video_id'),
+                    'client_info': ClientInfo(
+                        client_name=traverse_obj(client_info, ('clientName', {lambda x: ClientName[x]})),
+                        client_version=traverse_obj(client_info, 'clientVersion'),
+                        os_version=traverse_obj(client_info, 'osVersion'),
+                        os_name=traverse_obj(client_info, 'osName'),
+                        device_model=traverse_obj(client_info, 'deviceModel'),
+                        device_make=traverse_obj(client_info, 'deviceMake'),
+                    ),
+                    'target_duration_sec': sabr_config.get('target_duration_sec'),
+                    # Number.MAX_SAFE_INTEGER
+                    'start_time_ms': ((2**53) - 1) if info_dict.get('live_status') == 'is_live' and not f.get('is_from_start') else 0,
+                }
+
+            else:
+                if sabr_format_group_config['server_abr_streaming_url'] != server_abr_streaming_url:
+                    raise DownloadError('Server ABR streaming URL mismatch')
+
+                if sabr_format_group_config['video_playback_ustreamer_config'] != video_playback_ustreamer_config:
+                    raise DownloadError('Video playback ustreamer config mismatch')
+
+            itag = int_or_none(sabr_config.get('itag'))
+            sabr_format_group_config['formats'].append({
+                'display_name': f.get('format_id'),
+                'format_id': itag and FormatId(
+                    itag=itag, lmt=int_or_none(sabr_config.get('last_modified')), xtags=sabr_config.get('xtags')),
+                'format_type': format_type(f),
+                'quality': sabr_config.get('quality'),
+                'height': sabr_config.get('height'),
+                'filename': f.get('filepath', filename),
+                'info_dict': f,
+            })
+
+        return format_groups
+
+    def real_download(self, filename, info_dict):
+        format_groups = self._group_formats_by_client(filename, info_dict)
+
+        is_test = self.params.get('test', False)
+        resume = self.params.get('continuedl', True)
+
+        for client_name, format_group in format_groups.items():
+            formats = format_group['formats']
+            audio_formats = (f for f in formats if f['format_type'] == 'audio')
+            video_formats = (f for f in formats if f['format_type'] == 'video')
+            caption_formats = (f for f in formats if f['format_type'] == 'caption')
+            for audio_format, video_format, caption_format in itertools.zip_longest(audio_formats, video_formats, caption_formats):
+                format_str = join_nonempty(*[
+                    traverse_obj(audio_format, 'display_name'),
+                    traverse_obj(video_format, 'display_name'),
+                    traverse_obj(caption_format, 'display_name')], delim='+')
+                self.write_debug(f'Downloading formats: {format_str} ({client_name} client)')
+                self._download_sabr_stream(
+                    info_dict=info_dict,
+                    video_format=video_format,
+                    audio_format=audio_format,
+                    caption_format=caption_format,
+                    resume=resume,
+                    is_test=is_test,
+                    server_abr_streaming_url=format_group['server_abr_streaming_url'],
+                    video_playback_ustreamer_config=format_group['video_playback_ustreamer_config'],
+                    initial_po_token=format_group['initial_po_token'],
+                    fetch_po_token_fn=format_group['fetch_po_token_fn'],
+                    reload_config_fn=format_group['reload_config_fn'],
+                    client_info=format_group['client_info'],
+                    start_time_ms=format_group['start_time_ms'],
+                    target_duration_sec=format_group.get('target_duration_sec', None),
+                    live_status=format_group.get('live_status'),
+                    video_id=format_group.get('video_id'),
+                )
+        return True
+
+    def _download_sabr_stream(
+        self,
+        video_id: str,
+        info_dict: dict,
+        video_format: dict,
+        audio_format: dict,
+        caption_format: dict,
+        resume: bool,
+        is_test: bool,
+        server_abr_streaming_url: str,
+        video_playback_ustreamer_config: str,
+        initial_po_token: str,
+        fetch_po_token_fn: callable | None = None,
+        reload_config_fn: callable | None = None,
+        client_info: ClientInfo | None = None,
+        start_time_ms: int = 0,
+        target_duration_sec: int | None = None,
+        live_status: str | None = None,
+    ):
+
+        writers = {}
+        audio_selector = None
+        video_selector = None
+        caption_selector = None
+
+        if audio_format:
+            audio_selector = AudioSelector(
+                display_name=audio_format['display_name'], format_ids=[audio_format['format_id']])
+            writers[audio_selector.display_name] = SabrFDFormatWriter(
+                self, audio_format.get('filename'),
+                audio_format['info_dict'], len(writers), resume=resume)
+
+        if video_format:
+            video_selector = VideoSelector(
+                display_name=video_format['display_name'], format_ids=[video_format['format_id']])
+            writers[video_selector.display_name] = SabrFDFormatWriter(
+                self, video_format.get('filename'),
+                video_format['info_dict'], len(writers), resume=resume)
+
+        if caption_format:
+            caption_selector = CaptionSelector(
+                display_name=caption_format['display_name'], format_ids=[caption_format['format_id']])
+            writers[caption_selector.display_name] = SabrFDFormatWriter(
+                self, caption_format.get('filename'),
+                caption_format['info_dict'], len(writers), resume=resume)
+
+        stream = SabrStream(
+            urlopen=self.ydl.urlopen,
+            logger=create_sabrfd_logger(self.ydl, prefix='sabr:stream'),
+            server_abr_streaming_url=server_abr_streaming_url,
+            video_playback_ustreamer_config=video_playback_ustreamer_config,
+            po_token=initial_po_token,
+            video_selection=video_selector,
+            audio_selection=audio_selector,
+            caption_selection=caption_selector,
+            start_time_ms=start_time_ms,
+            client_info=client_info,
+            live_segment_target_duration_sec=target_duration_sec,
+            post_live=live_status == 'post_live',
+            video_id=video_id,
+            retry_sleep_func=self.params.get('retry_sleep_functions', {}).get('http'),
+        )
+
+        self._prepare_multiline_status(len(writers) + 1)
+
+        try:
+            total_bytes = 0
+            for part in stream:
+                if is_test and total_bytes >= self._TEST_FILE_SIZE:
+                    stream.close()
+                    break
+                if isinstance(part, PoTokenStatusSabrPart):
+                    if not fetch_po_token_fn:
+                        self.report_warning(
+                            'No fetch PO token function found - this can happen if you use --load-info-json.'
+                            ' The download will fail if a valid PO token is required.', only_once=True)
+                    if part.status in (
+                        part.PoTokenStatus.INVALID,
+                        part.PoTokenStatus.PENDING,
+                    ):
+                        # Fetch a PO token with bypass_cache=True
+                        # (ensure we create a new one)
+                        po_token = fetch_po_token_fn(bypass_cache=True)
+                        if po_token:
+                            stream.processor.po_token = po_token
+                    elif part.status in (
+                        part.PoTokenStatus.MISSING,
+                        part.PoTokenStatus.PENDING_MISSING,
+                    ):
+                        # Fetch a PO Token, bypass_cache=False
+                        po_token = fetch_po_token_fn()
+                        if po_token:
+                            stream.processor.po_token = po_token
+
+                elif isinstance(part, FormatInitializedSabrPart):
+                    writer = writers.get(part.format_selector.display_name)
+                    if not writer:
+                        self.report_warning(f'Unknown format selector: {part.format_selector}')
+                        continue
+
+                    writer.initialize_format(part.format_id)
+                    initialized_format = stream.processor.initialized_formats[str(part.format_id)]
+                    if writer.state.init_sequence:
+                        initialized_format.init_segment = True
+                        initialized_format.current_segment = None  # allow a seek
+
+                    # Build consumed ranges from the sequences
+                    consumed_ranges = []
+                    for sequence in writer.state.sequences:
+                        consumed_ranges.append(ConsumedRange(
+                            start_time_ms=sequence.first_segment.start_time_ms,
+                            duration_ms=(sequence.last_segment.start_time_ms + sequence.last_segment.duration_ms) - sequence.first_segment.start_time_ms,
+                            start_sequence_number=sequence.first_segment.sequence_number,
+                            end_sequence_number=sequence.last_segment.sequence_number,
+                        ))
+                    if consumed_ranges:
+                        initialized_format.consumed_ranges = consumed_ranges
+                        initialized_format.current_segment = None  # allow a seek
+                        self.to_screen(f'[download] Resuming download for format {part.format_selector.display_name}')
+
+                elif isinstance(part, MediaSegmentInitSabrPart):
+                    writer = writers.get(part.format_selector.display_name)
+                    if not writer:
+                        self.report_warning(f'Unknown init format selector: {part.format_selector}')
+                        continue
+                    writer.initialize_segment(part)
+
+                elif isinstance(part, MediaSegmentDataSabrPart):
+                    total_bytes += len(part.data)  # TODO: not reliable
+                    writer = writers.get(part.format_selector.display_name)
+                    if not writer:
+                        self.report_warning(f'Unknown data format selector: {part.format_selector}')
+                        continue
+                    writer.write_segment_data(part)
+
+                elif isinstance(part, MediaSegmentEndSabrPart):
+                    writer = writers.get(part.format_selector.display_name)
+                    if not writer:
+                        self.report_warning(f'Unknown end format selector: {part.format_selector}')
+                        continue
+                    writer.end_segment(part)
+
+                elif isinstance(part, RefreshPlayerResponseSabrPart):
+                    self.to_screen(f'Refreshing player response; Reason: {part.reason}')
+                    # In-place refresh - not ideal but should work in most cases
+                    # TODO: handle case where live stream changes to non-livestream on refresh?
+                    # TODO: if live, allow a seek as for non-DVR streams the reload may be longer than the buffer duration
+                    # TODO: handle po token function change
+                    if not reload_config_fn:
+                        raise self.report_warning(
+                            'No reload config function found - cannot refresh SABR streaming URL.'
+                            ' The url will expire soon and the download will fail.')
+                    try:
+                        stream.url, stream.processor.video_playback_ustreamer_config = reload_config_fn(part.reload_playback_token)
+                    except (TransportError, HTTPError) as e:
+                        self.report_warning(f'Failed to refresh SABR streaming URL: {e}')
+
+                elif isinstance(part, MediaSeekSabrPart):
+                    if (
+                        not info_dict.get('is_live')
+                        and live_status not in ('post_live', 'is_live')
+                        and not stream.processor.is_live
+                        and part.reason == MediaSeekSabrPart.Reason.SERVER_SEEK
+                    ):
+                        raise DownloadError('Server tried to seek a video')
+                else:
+                    self.to_screen(f'Unhandled part type: {part.__class__.__name__}')
+
+            for writer in writers.values():
+                writer.finish()
+        except SabrStreamError as e:
+            raise DownloadError(str(e)) from e
+        except KeyboardInterrupt:
+            if (
+                not info_dict.get('is_live')
+                and not live_status == 'is_live'
+                and not stream.processor.is_live
+            ):
+                raise
+            self.to_screen('Interrupted by user')
+            for writer in writers.values():
+                writer.finish()
+        finally:
+            # TODO: for livestreams, since we cannot resume them, should we finish the writers?
+            for writer in writers.values():
+                writer.close()
+
+
+def format_type(f):
+    if f.get('acodec') == 'none':
+        return 'video'
+    elif f.get('vcodec') == 'none':
+        return 'audio'
+    elif f.get('vcodec') is None and f.get('acodec') is None:
+        return 'caption'
+    return None
--- a/yt_dlp/downloader/sabr/_file.py
+++ b/yt_dlp/downloader/sabr/_file.py
@ -0,0 +1,196 @@
+from __future__ import annotations
+
+import dataclasses
+from yt_dlp.utils import DownloadError
+from ._io import DiskFormatIOBackend, MemoryFormatIOBackend
+
+
+@dataclasses.dataclass
+class Segment:
+    segment_id: str
+    content_length: int | None = None
+    content_length_estimated: bool = False
+    sequence_number: int | None = None
+    start_time_ms: int | None = None
+    duration_ms: int | None = None
+    duration_estimated: bool = False
+    is_init_segment: bool = False
+
+
+@dataclasses.dataclass
+class Sequence:
+    sequence_id: str
+    # The segments may not have a start byte range, so to keep it simple we will track
+    # length of the sequence. We can infer from this and the segment's content_length where they should end and begin.
+    sequence_content_length: int = 0
+    first_segment: Segment | None = None
+    last_segment: Segment | None = None
+
+
+class SequenceFile:
+
+    def __init__(self, fd, format_filename, sequence: Sequence, resume=False):
+        self.fd = fd
+        self.format_filename = format_filename
+        self.sequence = sequence
+        self.file = DiskFormatIOBackend(
+            fd=self.fd,
+            filename=self.format_filename + f'.sq{self.sequence_id}.sabr.part',
+        )
+        self.current_segment: SegmentFile | None = None
+        self.resume = resume
+
+        sequence_file_exists = self.file.exists()
+
+        if not resume and sequence_file_exists:
+            self.file.remove()
+
+        elif not self.sequence.last_segment and sequence_file_exists:
+            self.file.remove()
+
+        if self.sequence.last_segment and not sequence_file_exists:
+            raise DownloadError(f'Cannot find existing sequence {self.sequence_id} file')
+
+        if self.sequence.last_segment and not self.file.validate_length(self.sequence.sequence_content_length):
+            self.file.remove()
+            raise DownloadError(f'Existing sequence {self.sequence_id} file is not valid; removing')
+
+    @property
+    def sequence_id(self):
+        return self.sequence.sequence_id
+
+    @property
+    def current_length(self):
+        total = self.sequence.sequence_content_length
+        if self.current_segment:
+            total += self.current_segment.current_length
+        return total
+
+    def is_next_segment(self, segment: Segment):
+        if self.current_segment:
+            return False
+        latest_segment = self.sequence.last_segment or self.sequence.first_segment
+        if not latest_segment:
+            return True
+        if segment.is_init_segment and latest_segment.is_init_segment:
+            # Only one segment allowed for init segments
+            return False
+        return segment.sequence_number == latest_segment.sequence_number + 1
+
+    def is_current_segment(self, segment_id: str):
+        if not self.current_segment:
+            return False
+        return self.current_segment.segment_id == segment_id
+
+    def initialize_segment(self, segment: Segment):
+        if self.current_segment and not self.is_current_segment(segment.segment_id):
+            raise ValueError('Cannot reinitialize a segment that does not match the current segment')
+
+        if not self.current_segment and not self.is_next_segment(segment):
+            raise ValueError('Cannot initialize a segment that does not match the next segment')
+
+        self.current_segment = SegmentFile(
+            fd=self.fd,
+            format_filename=self.format_filename,
+            segment=segment,
+        )
+
+    def write_segment_data(self, data, segment_id: str):
+        if not self.is_current_segment(segment_id):
+            raise ValueError('Cannot write to a segment that does not match the current segment')
+
+        self.current_segment.write(data)
+
+    def end_segment(self, segment_id):
+        if not self.is_current_segment(segment_id):
+            raise ValueError('Cannot end a segment that does not exist')
+
+        self.current_segment.finish_write()
+
+        if (
+            self.current_segment.segment.content_length
+            and not self.current_segment.segment.content_length_estimated
+            and self.current_segment.current_length != self.current_segment.segment.content_length
+        ):
+            raise DownloadError(
+                f'Filesize mismatch for segment {self.current_segment.segment_id}: '
+                f'Expected {self.current_segment.segment.content_length} bytes, got {self.current_segment.current_length} bytes')
+
+        self.current_segment.segment.content_length = self.current_segment.current_length
+        self.current_segment.segment.content_length_estimated = False
+
+        if not self.sequence.first_segment:
+            self.sequence.first_segment = self.current_segment.segment
+
+        self.sequence.last_segment = self.current_segment.segment
+        self.sequence.sequence_content_length += self.current_segment.current_length
+
+        if not self.file.mode:
+            self.file.initialize_writer(self.resume)
+
+        self.current_segment.read_into(self.file)
+        self.current_segment.remove()
+        self.current_segment = None
+
+    def read_into(self, backend):
+        self.file.initialize_reader()
+        self.file.read_into(backend)
+        self.file.close()
+
+    def remove(self):
+        self.close()
+        self.file.remove()
+
+    def close(self):
+        self.file.close()
+
+
+class SegmentFile:
+
+    def __init__(self, fd, format_filename, segment: Segment, memory_file_limit=2 * 1024 * 1024):
+        self.fd = fd
+        self.format_filename = format_filename
+        self.segment: Segment = segment
+        self.current_length = 0
+
+        filename = format_filename + f'.sg{segment.sequence_number}.sabr.part'
+        # Store the segment in memory if it is small enough
+        if segment.content_length and segment.content_length <= memory_file_limit:
+            self.file = MemoryFormatIOBackend(
+                fd=self.fd,
+                filename=filename,
+            )
+        else:
+            self.file = DiskFormatIOBackend(
+                fd=self.fd,
+                filename=filename,
+            )
+
+        # Never resume a segment
+        exists = self.file.exists()
+        if exists:
+            self.file.remove()
+
+    @property
+    def segment_id(self):
+        return self.segment.segment_id
+
+    def write(self, data):
+        if not self.file.mode:
+            self.file.initialize_writer(resume=False)
+        self.current_length += self.file.write(data)
+
+    def read_into(self, file):
+        self.file.initialize_reader()
+        self.file.read_into(file)
+        self.file.close()
+
+    def remove(self):
+        self.close()
+        self.file.remove()
+
+    def finish_write(self):
+        self.close()
+
+    def close(self):
+        self.file.close()
--- a/yt_dlp/downloader/sabr/_io.py
+++ b/yt_dlp/downloader/sabr/_io.py
@ -0,0 +1,162 @@
+from __future__ import annotations
+import abc
+import io
+import os
+import shutil
+import typing
+
+
+class FormatIOBackend(abc.ABC):
+    def __init__(self, fd, filename, buffer=1024 * 1024):
+        self.fd = fd
+        self.filename = filename
+        self.write_buffer = buffer
+        self._fp = None
+        self._fp_mode = None
+
+    @property
+    def writer(self):
+        if self._fp is None or self._fp_mode != 'write':
+            return None
+        return self._fp
+
+    @property
+    def reader(self):
+        if self._fp is None or self._fp_mode != 'read':
+            return None
+        return self._fp
+
+    def initialize_writer(self, resume=False):
+        if self._fp is not None:
+            raise ValueError('Backend already initialized')
+
+        self._fp = self._create_writer(resume)
+        self._fp_mode = 'write'
+
+    @abc.abstractmethod
+    def _create_writer(self, resume=False) -> typing.IO:
+        pass
+
+    def initialize_reader(self):
+        if self._fp is not None:
+            raise ValueError('Backend already initialized')
+        self._fp = self._create_reader()
+        self._fp_mode = 'read'
+
+    @abc.abstractmethod
+    def _create_reader(self) -> typing.IO:
+        pass
+
+    def close(self):
+        if self._fp and not self._fp.closed:
+            self._fp.flush()
+            self._fp.close()
+        self._fp = None
+        self._fp_mode = None
+
+    @abc.abstractmethod
+    def validate_length(self, expected_length):
+        pass
+
+    def remove(self):
+        self.close()
+        self._remove()
+
+    @abc.abstractmethod
+    def _remove(self):
+        pass
+
+    @abc.abstractmethod
+    def exists(self):
+        pass
+
+    @property
+    def mode(self):
+        if self._fp is None:
+            return None
+        return self._fp_mode
+
+    def write(self, data: io.BufferedIOBase | bytes):
+        if not self.writer:
+            raise ValueError('Backend writer not initialized')
+
+        if isinstance(data, bytes):
+            bytes_written = self.writer.write(data)
+        elif isinstance(data, io.BufferedIOBase):
+            bytes_written = self.writer.tell()
+            shutil.copyfileobj(data, self.writer, length=self.write_buffer)
+            bytes_written = self.writer.tell() - bytes_written
+        else:
+            raise TypeError('Data must be bytes or a BufferedIOBase object')
+
+        self.writer.flush()
+
+        return bytes_written
+
+    def read_into(self, backend):
+        if not backend.writer:
+            raise ValueError('Backend writer not initialized')
+        if not self.reader:
+            raise ValueError('Backend reader not initialized')
+        shutil.copyfileobj(self.reader, backend.writer, length=self.write_buffer)
+        backend.writer.flush()
+
+
+class DiskFormatIOBackend(FormatIOBackend):
+    def _create_writer(self, resume=False) -> typing.IO:
+        if resume and self.exists():
+            write_fp, self.filename = self.fd.sanitize_open(self.filename, 'ab')
+        else:
+            write_fp, self.filename = self.fd.sanitize_open(self.filename, 'wb')
+        return write_fp
+
+    def _create_reader(self) -> typing.IO:
+        read_fp, self.filename = self.fd.sanitize_open(self.filename, 'rb')
+        return read_fp
+
+    def validate_length(self, expected_length):
+        return os.path.getsize(self.filename) == expected_length
+
+    def _remove(self):
+        self.fd.try_remove(self.filename)
+
+    def exists(self):
+        return os.path.isfile(self.filename)
+
+
+class MemoryFormatIOBackend(FormatIOBackend):
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+        self._memory_store = io.BytesIO()
+
+    def _create_writer(self, resume=False) -> typing.IO:
+        class NonClosingBufferedWriter(io.BufferedWriter):
+            def close(self):
+                self.flush()
+                # Do not close the underlying buffer
+
+        if resume and self.exists():
+            self._memory_store.seek(0, io.SEEK_END)
+        else:
+            self._memory_store.seek(0)
+            self._memory_store.truncate(0)
+
+        return NonClosingBufferedWriter(self._memory_store)
+
+    def _create_reader(self) -> typing.IO:
+        class NonClosingBufferedReader(io.BufferedReader):
+            def close(self):
+                self.flush()
+
+        # Seek to the beginning of the buffer
+        self._memory_store.seek(0)
+        return NonClosingBufferedReader(self._memory_store)
+
+    def validate_length(self, expected_length):
+        return self._memory_store.getbuffer().nbytes != expected_length
+
+    def _remove(self):
+        self._memory_store = io.BytesIO()
+
+    def exists(self):
+        return self._memory_store.getbuffer().nbytes > 0
--- a/yt_dlp/downloader/sabr/_logger.py
+++ b/yt_dlp/downloader/sabr/_logger.py
@ -0,0 +1,46 @@
+from __future__ import annotations
+
+from yt_dlp.utils import format_field, traverse_obj
+from yt_dlp.extractor.youtube._streaming.sabr.models import SabrLogger
+from yt_dlp.utils._utils import _YDLLogger
+
+# TODO: create a logger that logs to a file rather than the console.
+#  Might be useful for debugging SABR issues from users.
+
+
+class SabrFDLogger(SabrLogger):
+    def __init__(self, ydl, prefix, log_level: SabrLogger.LogLevel | None = None):
+        self._ydl_logger = _YDLLogger(ydl)
+        self.prefix = prefix
+        self.log_level = log_level if log_level is not None else self.LogLevel.INFO
+
+    def _format_msg(self, message: str):
+        prefixstr = format_field(self.prefix, None, '[%s] ')
+        return f'{prefixstr}{message}'
+
+    def trace(self, message: str):
+        if self.log_level <= self.LogLevel.TRACE:
+            self._ydl_logger.debug(self._format_msg('TRACE: ' + message))
+
+    def debug(self, message: str):
+        if self.log_level <= self.LogLevel.DEBUG:
+            self._ydl_logger.debug(self._format_msg(message))
+
+    def info(self, message: str):
+        if self.log_level <= self.LogLevel.INFO:
+            self._ydl_logger.info(self._format_msg(message))
+
+    def warning(self, message: str, *, once=False):
+        if self.log_level <= self.LogLevel.WARNING:
+            self._ydl_logger.warning(self._format_msg(message), once=once)
+
+    def error(self, message: str):
+        if self.log_level <= self.LogLevel.ERROR:
+            self._ydl_logger.error(self._format_msg(message), is_error=False)
+
+
+def create_sabrfd_logger(ydl, prefix):
+    return SabrFDLogger(
+        ydl, prefix=prefix,
+        log_level=SabrFDLogger.LogLevel(traverse_obj(
+            ydl.params, ('extractor_args', 'youtube', 'sabr_log_level', 0, {str}), get_all=False)))
--- a/yt_dlp/downloader/sabr/_state.py
+++ b/yt_dlp/downloader/sabr/_state.py
@ -0,0 +1,77 @@
+from __future__ import annotations
+import contextlib
+import os
+import tempfile
+
+from yt_dlp.dependencies import protobug
+from yt_dlp.extractor.youtube._proto.videostreaming import FormatId
+
+
+@protobug.message
+class SabrStateSegment:
+    sequence_number: protobug.Int32 = protobug.field(1)
+    start_time_ms: protobug.Int64 = protobug.field(2)
+    duration_ms: protobug.Int64 = protobug.field(3)
+    duration_estimated: protobug.Bool = protobug.field(4)
+    content_length: protobug.Int64 = protobug.field(5)
+
+
+@protobug.message
+class SabrStateSequence:
+    sequence_start_number: protobug.Int32 = protobug.field(1)
+    sequence_content_length: protobug.Int64 = protobug.field(2)
+    first_segment: SabrStateSegment = protobug.field(3)
+    last_segment: SabrStateSegment = protobug.field(4)
+
+
+@protobug.message
+class SabrStateInitSegment:
+    content_length: protobug.Int64 = protobug.field(2)
+
+
+@protobug.message
+class SabrState:
+    format_id: FormatId = protobug.field(1)
+    init_segment: SabrStateInitSegment | None = protobug.field(2, default=None)
+    sequences: list[SabrStateSequence] = protobug.field(3, default_factory=list)
+
+
+class SabrStateFile:
+
+    def __init__(self, format_filename, fd):
+        self.filename = format_filename + '.sabr.state'
+        self.fd = fd
+
+    @property
+    def exists(self):
+        return os.path.isfile(self.filename)
+
+    def retrieve(self):
+        stream, self.filename = self.fd.sanitize_open(self.filename, 'rb')
+        try:
+            return self.deserialize(stream.read())
+        finally:
+            stream.close()
+
+    def update(self, sabr_document):
+        # Attempt to write progress document somewhat atomically to avoid corruption
+        tf = tempfile.NamedTemporaryFile(delete=False, dir=os.path.dirname(self.filename))
+        try:
+            with open(tf.name, 'wb') as f:
+                f.write(self.serialize(sabr_document))
+                f.flush()
+                os.fsync(f.fileno())
+            os.replace(tf.name, self.filename)
+        finally:
+            if os.path.exists(tf.name):
+                with contextlib.suppress(FileNotFoundError, OSError):
+                    os.unlink(tf.name)
+
+    def serialize(self, sabr_document):
+        return protobug.dumps(sabr_document)
+
+    def deserialize(self, data):
+        return protobug.loads(data, SabrState)
+
+    def remove(self):
+        self.fd.try_remove(self.filename)
--- a/yt_dlp/downloader/sabr/_writer.py
+++ b/yt_dlp/downloader/sabr/_writer.py
@ -0,0 +1,355 @@
+from __future__ import annotations
+
+import dataclasses
+
+from ._io import DiskFormatIOBackend
+from ._file import SequenceFile, Sequence, Segment
+from ._state import (
+    SabrStateSegment,
+    SabrStateSequence,
+    SabrStateInitSegment,
+    SabrState,
+    SabrStateFile,
+)
+from yt_dlp.extractor.youtube._streaming.sabr.part import (
+    MediaSegmentInitSabrPart,
+    MediaSegmentDataSabrPart,
+    MediaSegmentEndSabrPart,
+)
+
+from yt_dlp.utils import DownloadError
+from yt_dlp.extractor.youtube._proto.videostreaming import FormatId
+from yt_dlp.utils.progress import ProgressCalculator
+
+INIT_SEGMENT_ID = 'i'
+
+
+@dataclasses.dataclass
+class SabrFormatState:
+    format_id: FormatId
+    init_sequence: Sequence | None = None
+    sequences: list[Sequence] = dataclasses.field(default_factory=list)
+
+
+class SabrFDFormatWriter:
+    def __init__(self, fd, filename, infodict, progress_idx=0, resume=False):
+        self.fd = fd
+        self.info_dict = infodict
+        self.filename = filename
+        self.progress_idx = progress_idx
+        self.resume = resume
+
+        self._progress = None
+        self._downloaded_bytes = 0
+        self._state = {}
+        self._format_id = None
+
+        self.file = DiskFormatIOBackend(
+            fd=self.fd,
+            filename=self.fd.temp_name(filename),
+        )
+        self._sabr_state_file = SabrStateFile(format_filename=self.filename, fd=fd)
+        self._sequence_files: list[SequenceFile] = []
+        self._init_sequence: SequenceFile | None = None
+
+    @property
+    def state(self):
+        return SabrFormatState(
+            format_id=self._format_id,
+            init_sequence=self._init_sequence.sequence if self._init_sequence else None,
+            sequences=[sf.sequence for sf in self._sequence_files],
+        )
+
+    @property
+    def downloaded_bytes(self):
+        return (sum(
+            sequence.current_length for sequence in self._sequence_files)
+            + (self._init_sequence.current_length if self._init_sequence else 0))
+
+    def initialize_format(self, format_id):
+        if self._format_id:
+            raise ValueError('Already initialized')
+        self._format_id = format_id
+
+        if not self.resume:
+            if self._sabr_state_file.exists:
+                self._sabr_state_file.remove()
+            return
+
+        document = self._load_sabr_state()
+
+        if document.init_segment:
+            init_segment = Segment(
+                segment_id=INIT_SEGMENT_ID,
+                content_length=document.init_segment.content_length,
+                is_init_segment=True,
+            )
+
+            try:
+                self._init_sequence = SequenceFile(
+                    fd=self.fd,
+                    format_filename=self.filename,
+                    resume=True,
+                    sequence=Sequence(
+                        sequence_id=INIT_SEGMENT_ID,
+                        sequence_content_length=init_segment.content_length,
+                        first_segment=init_segment,
+                        last_segment=init_segment,
+                    ))
+            except DownloadError as e:
+                self.fd.report_warning(f'Failed to resume init segment for format {self.info_dict.get("format_id")}: {e}')
+
+        for sabr_sequence in list(document.sequences):
+            try:
+                self._sequence_files.append(SequenceFile(
+                    fd=self.fd,
+                    format_filename=self.filename,
+                    resume=True,
+                    sequence=Sequence(
+                        sequence_id=str(sabr_sequence.sequence_start_number),
+                        sequence_content_length=sabr_sequence.sequence_content_length,
+                        first_segment=Segment(
+                            segment_id=str(sabr_sequence.first_segment.sequence_number),
+                            sequence_number=sabr_sequence.first_segment.sequence_number,
+                            content_length=sabr_sequence.first_segment.content_length,
+                            start_time_ms=sabr_sequence.first_segment.start_time_ms,
+                            duration_ms=sabr_sequence.first_segment.duration_ms,
+                            is_init_segment=False,
+                        ),
+                        last_segment=Segment(
+                            segment_id=str(sabr_sequence.last_segment.sequence_number),
+                            sequence_number=sabr_sequence.last_segment.sequence_number,
+                            content_length=sabr_sequence.last_segment.content_length,
+                            start_time_ms=sabr_sequence.last_segment.start_time_ms,
+                            duration_ms=sabr_sequence.last_segment.duration_ms,
+                            is_init_segment=False,
+                        ),
+                    ),
+                ))
+            except DownloadError as e:
+                self.fd.report_warning(
+                    f'Failed to resume sequence {sabr_sequence.sequence_start_number} '
+                    f'for format {self.info_dict.get("format_id")}: {e}')
+
+    @property
+    def initialized(self):
+        return self._format_id is not None
+
+    def close(self):
+        if not self.file:
+            raise ValueError('Already closed')
+        for sequence in self._sequence_files:
+            sequence.close()
+        self._sequence_files.clear()
+        if self._init_sequence:
+            self._init_sequence.close()
+            self._init_sequence = None
+        self.file.close()
+
+    def _find_sequence_file(self, predicate):
+        match = None
+        for sequence in self._sequence_files:
+            if predicate(sequence):
+                if match is not None:
+                    raise DownloadError('Multiple sequence files found for segment')
+                match = sequence
+        return match
+
+    def find_next_sequence_file(self, next_segment: Segment):
+        return self._find_sequence_file(lambda sequence: sequence.is_next_segment(next_segment))
+
+    def find_current_sequence_file(self, segment_id: str):
+        return self._find_sequence_file(lambda sequence: sequence.is_current_segment(segment_id))
+
+    def initialize_segment(self, part: MediaSegmentInitSabrPart):
+        if not self._progress:
+            self._progress = ProgressCalculator(part.start_bytes)
+
+        if not self._format_id:
+            raise ValueError('not initialized')
+
+        if part.is_init_segment:
+            if not self._init_sequence:
+                self._init_sequence = SequenceFile(
+                    fd=self.fd,
+                    format_filename=self.filename,
+                    resume=False,
+                    sequence=Sequence(
+                        sequence_id=INIT_SEGMENT_ID,
+                    ))
+
+            self._init_sequence.initialize_segment(Segment(
+                segment_id=INIT_SEGMENT_ID,
+                content_length=part.content_length,
+                content_length_estimated=part.content_length_estimated,
+                is_init_segment=True,
+            ))
+            return True
+
+        segment = Segment(
+            segment_id=str(part.sequence_number),
+            sequence_number=part.sequence_number,
+            start_time_ms=part.start_time_ms,
+            duration_ms=part.duration_ms,
+            duration_estimated=part.duration_estimated,
+            content_length=part.content_length,
+            content_length_estimated=part.content_length_estimated,
+        )
+
+        sequence_file = self.find_current_sequence_file(segment.segment_id) or self.find_next_sequence_file(segment)
+
+        if not sequence_file:
+            sequence_file = SequenceFile(
+                fd=self.fd,
+                format_filename=self.filename,
+                resume=False,
+                sequence=Sequence(sequence_id=str(part.sequence_number)),
+            )
+            self._sequence_files.append(sequence_file)
+
+        sequence_file.initialize_segment(segment)
+        return True
+
+    def write_segment_data(self, part: MediaSegmentDataSabrPart):
+        if part.is_init_segment:
+            sequence_file, segment_id = self._init_sequence, INIT_SEGMENT_ID
+        else:
+            segment_id = str(part.sequence_number)
+            sequence_file = self.find_current_sequence_file(segment_id)
+
+        if not sequence_file:
+            raise DownloadError('Unable to find sequence file for segment. Was the segment initialized?')
+
+        sequence_file.write_segment_data(part.data, segment_id)
+
+        # TODO: Handling of disjointed segments (e.g. when downloading segments out of order / concurrently)
+        self._progress.total = self.info_dict.get('filesize')
+        self._state = {
+            'status': 'downloading',
+            'downloaded_bytes': self.downloaded_bytes,
+            'total_bytes': self.info_dict.get('filesize'),
+            'filename': self.filename,
+            'eta': self._progress.eta.smooth,
+            'speed': self._progress.speed.smooth,
+            'elapsed': self._progress.elapsed,
+            'progress_idx': self.progress_idx,
+            'fragment_count': part.total_segments,
+            'fragment_index': part.sequence_number,
+        }
+
+        self._progress.update(self._state['downloaded_bytes'])
+        self.fd._hook_progress(self._state, self.info_dict)
+
+    def end_segment(self, part: MediaSegmentEndSabrPart):
+        if part.is_init_segment:
+            sequence_file, segment_id = self._init_sequence, INIT_SEGMENT_ID
+        else:
+            segment_id = str(part.sequence_number)
+            sequence_file = self.find_current_sequence_file(segment_id)
+
+        if not sequence_file:
+            raise DownloadError('Unable to find sequence file for segment. Was the segment initialized?')
+
+        sequence_file.end_segment(segment_id)
+        self._write_sabr_state()
+
+    def _load_sabr_state(self):
+        sabr_state = None
+        if self._sabr_state_file.exists:
+            try:
+                sabr_state = self._sabr_state_file.retrieve()
+            except Exception:
+                self.fd.report_warning(
+                    f'Corrupted state file for format {self.info_dict.get("format_id")}, restarting download')
+
+        if sabr_state and sabr_state.format_id != self._format_id:
+            self.fd.report_warning(
+                f'Format ID mismatch in state file for {self.info_dict.get("format_id")}, restarting download')
+            sabr_state = None
+
+        if not sabr_state:
+            sabr_state = SabrState(format_id=self._format_id)
+
+        return sabr_state
+
+    def _write_sabr_state(self):
+        sabr_state = SabrState(format_id=self._format_id)
+
+        if not self._init_sequence:
+            sabr_state.init_segment = None
+        else:
+            sabr_state.init_segment = SabrStateInitSegment(
+                content_length=self._init_sequence.sequence.sequence_content_length,
+            )
+
+        sabr_state.sequences = []
+        for sequence_file in self._sequence_files:
+            # Ignore partial sequences
+            if not sequence_file.sequence.first_segment or not sequence_file.sequence.last_segment:
+                continue
+            sabr_state.sequences.append(SabrStateSequence(
+                sequence_start_number=sequence_file.sequence.first_segment.sequence_number,
+                sequence_content_length=sequence_file.sequence.sequence_content_length,
+                first_segment=SabrStateSegment(
+                    sequence_number=sequence_file.sequence.first_segment.sequence_number,
+                    start_time_ms=sequence_file.sequence.first_segment.start_time_ms,
+                    duration_ms=sequence_file.sequence.first_segment.duration_ms,
+                    duration_estimated=sequence_file.sequence.first_segment.duration_estimated,
+                    content_length=sequence_file.sequence.first_segment.content_length,
+                ),
+                last_segment=SabrStateSegment(
+                    sequence_number=sequence_file.sequence.last_segment.sequence_number,
+                    start_time_ms=sequence_file.sequence.last_segment.start_time_ms,
+                    duration_ms=sequence_file.sequence.last_segment.duration_ms,
+                    duration_estimated=sequence_file.sequence.last_segment.duration_estimated,
+                    content_length=sequence_file.sequence.last_segment.content_length,
+                ),
+            ))
+
+        self._sabr_state_file.update(sabr_state)
+
+    def finish(self):
+        self._state['status'] = 'finished'
+        self.fd._hook_progress(self._state, self.info_dict)
+
+        for sequence_file in self._sequence_files:
+            sequence_file.close()
+
+        if self._init_sequence:
+            self._init_sequence.close()
+
+        # Now merge all the sequences together
+        self.file.initialize_writer(resume=False)
+
+        # Note: May not always be an init segment, e.g for live streams
+        if self._init_sequence:
+            self._init_sequence.read_into(self.file)
+            self._init_sequence.close()
+
+        # TODO: handling of disjointed segments
+        previous_seq_number = None
+        for sequence_file in sorted(
+                (sf for sf in self._sequence_files if sf.sequence.first_segment),
+                key=lambda s: s.sequence.first_segment.sequence_number):
+            if previous_seq_number and previous_seq_number + 1 != sequence_file.sequence.first_segment.sequence_number:
+                self.fd.report_warning(f'Disjointed sequences found in SABR format {self.info_dict.get("format_id")}')
+            previous_seq_number = sequence_file.sequence.last_segment.sequence_number
+            sequence_file.read_into(self.file)
+            sequence_file.close()
+
+        # Format temp file should have all the segments, rename it to the final name
+        self.file.close()
+        self.fd.try_rename(self.file.filename, self.fd.undo_temp_name(self.file.filename))
+
+        # Remove the state file
+        self._sabr_state_file.remove()
+
+        # Remove sequence files
+        for sf in self._sequence_files:
+            sf.close()
+            sf.remove()
+
+        if self._init_sequence:
+            self._init_sequence.close()
+            self._init_sequence.remove()
+        self.close()
--- a/yt_dlp/extractor/youtube/_proto/init.py
+++ b/yt_dlp/extractor/youtube/_proto/init.py
@ -0,0 +1,14 @@
+import dataclasses
+import typing
+
+
+def unknown_fields(obj: typing.Any, path=()) -> typing.Iterable[tuple[tuple[str, ...], dict[int, list]]]:
+    if not dataclasses.is_dataclass(obj):
+        return
+
+    if unknown := getattr(obj, '_unknown', None):
+        yield path, unknown
+
+    for field in dataclasses.fields(obj):
+        value = getattr(obj, field.name)
+        yield from unknown_fields(value, (*path, field.name))
--- a/yt_dlp/extractor/youtube/_proto/innertube/init.py
+++ b/yt_dlp/extractor/youtube/_proto/innertube/init.py
@ -0,0 +1,5 @@
+from .client_info import ClientInfo, ClientName  # noqa: F401
+from .compression_algorithm import CompressionAlgorithm  # noqa: F401
+from .next_request_policy import NextRequestPolicy  # noqa: F401
+from .range import Range  # noqa: F401
+from .seek_source import SeekSource  # noqa: F401
--- a/yt_dlp/extractor/youtube/_proto/innertube/client_info.py
+++ b/yt_dlp/extractor/youtube/_proto/innertube/client_info.py
@ -0,0 +1,105 @@
+from __future__ import annotations
+
+from yt_dlp.dependencies import protobug
+
+
+class ClientName(protobug.Enum, strict=False):
+    UNKNOWN_INTERFACE = 0
+    WEB = 1
+    MWEB = 2
+    ANDROID = 3
+    IOS = 5
+    TVHTML5 = 7
+    TVLITE = 8
+    TVANDROID = 10
+    XBOX = 11
+    CLIENTX = 12
+    XBOXONEGUIDE = 13
+    ANDROID_CREATOR = 14
+    IOS_CREATOR = 15
+    TVAPPLE = 16
+    IOS_INSTANT = 17
+    ANDROID_KIDS = 18
+    IOS_KIDS = 19
+    ANDROID_INSTANT = 20
+    ANDROID_MUSIC = 21
+    IOS_TABLOID = 22
+    ANDROID_TV = 23
+    ANDROID_GAMING = 24
+    IOS_GAMING = 25
+    IOS_MUSIC = 26
+    MWEB_TIER_2 = 27
+    ANDROID_VR = 28
+    ANDROID_UNPLUGGED = 29
+    ANDROID_TESTSUITE = 30
+    WEB_MUSIC_ANALYTICS = 31
+    WEB_GAMING = 32
+    IOS_UNPLUGGED = 33
+    ANDROID_WITNESS = 34
+    IOS_WITNESS = 35
+    ANDROID_SPORTS = 36
+    IOS_SPORTS = 37
+    ANDROID_LITE = 38
+    IOS_EMBEDDED_PLAYER = 39
+    IOS_DIRECTOR = 40
+    WEB_UNPLUGGED = 41
+    WEB_EXPERIMENTS = 42
+    TVHTML5_CAST = 43
+    WEB_EMBEDDED_PLAYER = 56
+    TVHTML5_AUDIO = 57
+    TV_UNPLUGGED_CAST = 58
+    TVHTML5_KIDS = 59
+    WEB_HEROES = 60
+    WEB_MUSIC = 61
+    WEB_CREATOR = 62
+    TV_UNPLUGGED_ANDROID = 63
+    IOS_LIVE_CREATION_EXTENSION = 64
+    TVHTML5_UNPLUGGED = 65
+    IOS_MESSAGES_EXTENSION = 66
+    WEB_REMIX = 67
+    IOS_UPTIME = 68
+    WEB_UNPLUGGED_ONBOARDING = 69
+    WEB_UNPLUGGED_OPS = 70
+    WEB_UNPLUGGED_PUBLIC = 71
+    TVHTML5_VR = 72
+    WEB_LIVE_STREAMING = 73
+    ANDROID_TV_KIDS = 74
+    TVHTML5_SIMPLY = 75
+    WEB_KIDS = 76
+    MUSIC_INTEGRATIONS = 77
+    TVHTML5_YONGLE = 80
+    GOOGLE_ASSISTANT = 84
+    TVHTML5_SIMPLY_EMBEDDED_PLAYER = 85
+    WEB_MUSIC_EMBEDDED_PLAYER = 86
+    WEB_INTERNAL_ANALYTICS = 87
+    WEB_PARENT_TOOLS = 88
+    GOOGLE_MEDIA_ACTIONS = 89
+    WEB_PHONE_VERIFICATION = 90
+    ANDROID_PRODUCER = 91
+    IOS_PRODUCER = 92
+    TVHTML5_FOR_KIDS = 93
+    GOOGLE_LIST_RECS = 94
+    MEDIA_CONNECT_FRONTEND = 95
+    WEB_EFFECT_MAKER = 98
+    WEB_SHOPPING_EXTENSION = 99
+    WEB_PLAYABLES_PORTAL = 100
+    VISIONOS = 101
+    WEB_LIVE_APPS = 102
+    WEB_MUSIC_INTEGRATIONS = 103
+    ANDROID_MUSIC_AOSP = 104
+
+
+@protobug.message
+class ClientInfo:
+    hl: protobug.String | None = protobug.field(1, default=None)
+    gl: protobug.String | None = protobug.field(2, default=None)
+    remote_host: protobug.String | None = protobug.field(4, default=None)
+
+    device_make: protobug.String | None = protobug.field(12, default=None)
+    device_model: protobug.String | None = protobug.field(13, default=None)
+    visitor_data: protobug.String | None = protobug.field(14, default=None)
+    user_agent: protobug.String | None = protobug.field(15, default=None)
+    client_name: ClientName | None = protobug.field(16, default=None)
+    client_version: protobug.String | None = protobug.field(17, default=None)
+    os_name: protobug.String | None = protobug.field(18, default=None)
+    os_version: protobug.String | None = protobug.field(19, default=None)
--- a/yt_dlp/extractor/youtube/_proto/innertube/compression_algorithm.py
+++ b/yt_dlp/extractor/youtube/_proto/innertube/compression_algorithm.py
@ -0,0 +1,7 @@
+from yt_dlp.dependencies import protobug
+
+
+class CompressionAlgorithm(protobug.Enum, strict=False):
+    COMPRESSION_ALGORITHM_UNKNOWN = 0
+    COMPRESSION_ALGORITHM_NONE = 1
+    COMPRESSION_ALGORITHM_GZIP = 2
--- a/yt_dlp/extractor/youtube/_proto/innertube/next_request_policy.py
+++ b/yt_dlp/extractor/youtube/_proto/innertube/next_request_policy.py
@ -0,0 +1,15 @@
+from __future__ import annotations
+
+from yt_dlp.dependencies import protobug
+
+
+@protobug.message
+class NextRequestPolicy:
+    target_audio_readahead_ms: protobug.Int32 | None = protobug.field(1, default=None)
+    target_video_readahead_ms: protobug.Int32 | None = protobug.field(2, default=None)
+    max_time_since_last_request_ms: protobug.Int32 | None = protobug.field(3, default=None)
+    backoff_time_ms: protobug.Int32 | None = protobug.field(4, default=None)
+    min_audio_readahead_ms: protobug.Int32 | None = protobug.field(5, default=None)
+    min_video_readahead_ms: protobug.Int32 | None = protobug.field(6, default=None)
+    playback_cookie: protobug.Bytes | None = protobug.field(7, default=None)
+    video_id: protobug.String | None = protobug.field(8, default=None)
--- a/yt_dlp/extractor/youtube/_proto/innertube/range.py
+++ b/yt_dlp/extractor/youtube/_proto/innertube/range.py
@ -0,0 +1,9 @@
+from __future__ import annotations
+
+from yt_dlp.dependencies import protobug
+
+
+@protobug.message
+class Range:
+    start: protobug.Int64 | None = protobug.field(1, default=None)
+    end: protobug.Int64 | None = protobug.field(2, default=None)
--- a/yt_dlp/extractor/youtube/_proto/innertube/seek_source.py
+++ b/yt_dlp/extractor/youtube/_proto/innertube/seek_source.py
@ -0,0 +1,14 @@
+from yt_dlp.dependencies import protobug
+
+
+class SeekSource(protobug.Enum, strict=False):
+    SEEK_SOURCE_UNKNOWN = 0
+    SEEK_SOURCE_SABR_PARTIAL_CHUNK = 9
+    SEEK_SOURCE_SABR_SEEK_TO_HEAD = 10
+    SEEK_SOURCE_SABR_LIVE_DVR_USER_SEEK = 11
+    SEEK_SOURCE_SABR_SEEK_TO_DVR_LOWER_BOUND = 12
+    SEEK_SOURCE_SABR_SEEK_TO_DVR_UPPER_BOUND = 13
+    SEEK_SOURCE_SABR_ACCURATE_SEEK = 17
+    SEEK_SOURCE_SABR_INGESTION_WALL_TIME_SEEK = 29
+    SEEK_SOURCE_SABR_SEEK_TO_CLOSEST_KEYFRAME = 59
+    SEEK_SOURCE_SABR_RELOAD_PLAYER_RESPONSE_TOKEN_SEEK = 106
--- a/yt_dlp/extractor/youtube/_proto/videostreaming/init.py
+++ b/yt_dlp/extractor/youtube/_proto/videostreaming/init.py
@ -0,0 +1,16 @@
+from .buffered_range import BufferedRange  # noqa: F401
+from .client_abr_state import ClientAbrState  # noqa: F401
+from .format_id import FormatId  # noqa: F401
+from .format_initialization_metadata import FormatInitializationMetadata  # noqa: F401
+from .live_metadata import LiveMetadata  # noqa: F401
+from .media_header import MediaHeader  # noqa: F401
+from .reload_player_response import ReloadPlayerResponse  # noqa: F401
+from .sabr_context_sending_policy import SabrContextSendingPolicy  # noqa: F401
+from .sabr_context_update import SabrContextUpdate  # noqa: F401
+from .sabr_error import SabrError  # noqa: F401
+from .sabr_redirect import SabrRedirect  # noqa: F401
+from .sabr_seek import SabrSeek  # noqa: F401
+from .stream_protection_status import StreamProtectionStatus  # noqa: F401
+from .streamer_context import SabrContext, StreamerContext  # noqa: F401
+from .time_range import TimeRange  # noqa: F401
+from .video_playback_abr_request import VideoPlaybackAbrRequest  # noqa: F401
--- a/yt_dlp/extractor/youtube/_proto/videostreaming/buffered_range.py
+++ b/yt_dlp/extractor/youtube/_proto/videostreaming/buffered_range.py
@ -0,0 +1,16 @@
+from __future__ import annotations
+
+from yt_dlp.dependencies import protobug
+
+from .format_id import FormatId
+from .time_range import TimeRange
+
+
+@protobug.message
+class BufferedRange:
+    format_id: FormatId | None = protobug.field(1, default=None)
+    start_time_ms: protobug.Int64 | None = protobug.field(2, default=None)
+    duration_ms: protobug.Int64 | None = protobug.field(3, default=None)
+    start_segment_index: protobug.Int32 | None = protobug.field(4, default=None)
+    end_segment_index: protobug.Int32 | None = protobug.field(5, default=None)
+    time_range: TimeRange | None = protobug.field(6, default=None)
--- a/yt_dlp/extractor/youtube/_proto/videostreaming/client_abr_state.py
+++ b/yt_dlp/extractor/youtube/_proto/videostreaming/client_abr_state.py
@ -0,0 +1,9 @@
+from __future__ import annotations
+
+from yt_dlp.dependencies import protobug
+
+
+@protobug.message
+class ClientAbrState:
+    player_time_ms: protobug.Int64 | None = protobug.field(28, default=None)
+    enabled_track_types_bitfield: protobug.Int32 | None = protobug.field(40, default=None)
--- a/yt_dlp/extractor/youtube/_proto/videostreaming/format_id.py
+++ b/yt_dlp/extractor/youtube/_proto/videostreaming/format_id.py
@ -0,0 +1,10 @@
+from __future__ import annotations
+
+from yt_dlp.dependencies import protobug
+
+
+@protobug.message
+class FormatId:
+    itag: protobug.Int32 | None = protobug.field(1)
+    lmt: protobug.UInt64 | None = protobug.field(2, default=None)
+    xtags: protobug.String | None = protobug.field(3, default=None)
--- a/yt_dlp/extractor/youtube/_proto/videostreaming/format_initialization_metadata.py
+++ b/yt_dlp/extractor/youtube/_proto/videostreaming/format_initialization_metadata.py
@ -0,0 +1,19 @@
+from __future__ import annotations
+
+from yt_dlp.dependencies import protobug
+
+from .format_id import FormatId
+from ..innertube import Range
+
+
+@protobug.message
+class FormatInitializationMetadata:
+    video_id: protobug.String = protobug.field(1, default=None)
+    format_id: FormatId = protobug.field(2, default=None)
+    end_time_ms: protobug.Int32 | None = protobug.field(3, default=None)
+    total_segments: protobug.Int32 | None = protobug.field(4, default=None)
+    mime_type: protobug.String | None = protobug.field(5, default=None)
+    init_range: Range | None = protobug.field(6, default=None)
+    index_range: Range | None = protobug.field(7, default=None)
+    duration_ticks: protobug.Int32 | None = protobug.field(9, default=None)
+    duration_timescale: protobug.Int32 | None = protobug.field(10, default=None)
--- a/yt_dlp/extractor/youtube/_proto/videostreaming/live_metadata.py
+++ b/yt_dlp/extractor/youtube/_proto/videostreaming/live_metadata.py
@ -0,0 +1,18 @@
+from __future__ import annotations
+
+from yt_dlp.dependencies import protobug
+
+
+@protobug.message
+class LiveMetadata:
+    head_sequence_number: protobug.Int32 | None = protobug.field(3, default=None)
+    head_sequence_time_ms: protobug.Int64 | None = protobug.field(4, default=None)
+    wall_time_ms: protobug.Int64 | None = protobug.field(5, default=None)
+    video_id: protobug.String | None = protobug.field(6, default=None)
+    source: protobug.String | None = protobug.field(7, default=None)
+
+    min_seekable_time_ticks: protobug.Int64 | None = protobug.field(12, default=None)
+    min_seekable_timescale: protobug.Int32 | None = protobug.field(13, default=None)
+
+    max_seekable_time_ticks: protobug.Int64 | None = protobug.field(14, default=None)
+    max_seekable_timescale: protobug.Int32 | None = protobug.field(15, default=None)
--- a/yt_dlp/extractor/youtube/_proto/videostreaming/media_header.py
+++ b/yt_dlp/extractor/youtube/_proto/videostreaming/media_header.py
@ -0,0 +1,27 @@
+from __future__ import annotations
+
+from yt_dlp.dependencies import protobug
+
+from .format_id import FormatId
+from .time_range import TimeRange
+from ..innertube import CompressionAlgorithm
+
+
+@protobug.message
+class MediaHeader:
+    header_id: protobug.UInt32 | None = protobug.field(1, default=None)
+    video_id: protobug.String | None = protobug.field(2, default=None)
+    itag: protobug.Int32 | None = protobug.field(3, default=None)
+    last_modified: protobug.UInt64 | None = protobug.field(4, default=None)
+    xtags: protobug.String | None = protobug.field(5, default=None)
+    start_data_range: protobug.Int32 | None = protobug.field(6, default=None)
+    compression: CompressionAlgorithm | None = protobug.field(7, default=None)
+    is_init_segment: protobug.Bool | None = protobug.field(8, default=None)
+    sequence_number: protobug.Int64 | None = protobug.field(9, default=None)
+    bitrate_bps: protobug.Int64 | None = protobug.field(10, default=None)
+    start_ms: protobug.Int32 | None = protobug.field(11, default=None)
+    duration_ms: protobug.Int32 | None = protobug.field(12, default=None)
+    format_id: FormatId | None = protobug.field(13, default=None)
+    content_length: protobug.Int64 | None = protobug.field(14, default=None)
+    time_range: TimeRange | None = protobug.field(15, default=None)
+    sequence_lmt: protobug.Int32 | None = protobug.field(16, default=None)
--- a/yt_dlp/extractor/youtube/_proto/videostreaming/reload_player_response.py
+++ b/yt_dlp/extractor/youtube/_proto/videostreaming/reload_player_response.py
@ -0,0 +1,13 @@
+from __future__ import annotations
+
+from yt_dlp.dependencies import protobug
+
+
+@protobug.message
+class ReloadPlaybackParams:
+    token: protobug.String | None = protobug.field(1, default=None)
+
+
+@protobug.message
+class ReloadPlayerResponse:
+    reload_playback_params: ReloadPlaybackParams | None = protobug.field(1, default=None)
--- a/yt_dlp/extractor/youtube/_proto/videostreaming/sabr_context_sending_policy.py
+++ b/yt_dlp/extractor/youtube/_proto/videostreaming/sabr_context_sending_policy.py
@ -0,0 +1,13 @@
+from yt_dlp.dependencies import protobug
+
+
+@protobug.message
+class SabrContextSendingPolicy:
+    # Start sending the SabrContextUpdates of this type
+    start_policy: list[protobug.Int32] = protobug.field(1, default_factory=list)
+
+    # Stop sending the SabrContextUpdates of this type
+    stop_policy: list[protobug.Int32] = protobug.field(2, default_factory=list)
+
+    # Stop and discard the SabrContextUpdates of this type
+    discard_policy: list[protobug.Int32] = protobug.field(3, default_factory=list)
--- a/yt_dlp/extractor/youtube/_proto/videostreaming/sabr_context_update.py
+++ b/yt_dlp/extractor/youtube/_proto/videostreaming/sabr_context_update.py
@ -0,0 +1,25 @@
+from __future__ import annotations
+
+from yt_dlp.dependencies import protobug
+
+
+@protobug.message
+class SabrContextUpdate:
+
+    class SabrContextScope(protobug.Enum, strict=False):
+        SABR_CONTEXT_SCOPE_UNKNOWN = 0
+        SABR_CONTEXT_SCOPE_PLAYBACK = 1
+        SABR_CONTEXT_SCOPE_REQUEST = 2
+        SABR_CONTEXT_SCOPE_WATCH_ENDPOINT = 3
+        SABR_CONTEXT_SCOPE_CONTENT_ADS = 4
+
+    class SabrContextWritePolicy(protobug.Enum, strict=False):
+        SABR_CONTEXT_WRITE_POLICY_UNSPECIFIED = 0
+        SABR_CONTEXT_WRITE_POLICY_OVERWRITE = 1
+        SABR_CONTEXT_WRITE_POLICY_KEEP_EXISTING = 2
+
+    type: protobug.Int32 | None = protobug.field(1, default=None)
+    scope: SabrContextScope | None = protobug.field(2, default=None)
+    value: protobug.Bytes | None = protobug.field(3, default=None)
+    send_by_default: protobug.Bool | None = protobug.field(4, default=None)
+    write_policy: SabrContextWritePolicy | None = protobug.field(5, default=None)
--- a/yt_dlp/extractor/youtube/_proto/videostreaming/sabr_error.py
+++ b/yt_dlp/extractor/youtube/_proto/videostreaming/sabr_error.py
@ -0,0 +1,16 @@
+from __future__ import annotations
+
+from yt_dlp.dependencies import protobug
+
+
+@protobug.message
+class Error:
+    status_code: protobug.Int32 | None = protobug.field(1, default=None)
+    type: protobug.Int32 | None = protobug.field(4, default=None)
+
+
+@protobug.message
+class SabrError:
+    type: protobug.String | None = protobug.field(1, default=None)
+    action: protobug.Int32 | None = protobug.field(2, default=None)
+    error: Error | None = protobug.field(3, default=None)
--- a/yt_dlp/extractor/youtube/_proto/videostreaming/sabr_redirect.py
+++ b/yt_dlp/extractor/youtube/_proto/videostreaming/sabr_redirect.py
@ -0,0 +1,8 @@
+from __future__ import annotations
+
+from yt_dlp.dependencies import protobug
+
+
+@protobug.message
+class SabrRedirect:
+    redirect_url: protobug.String | None = protobug.field(1, default=None)
--- a/yt_dlp/extractor/youtube/_proto/videostreaming/sabr_seek.py
+++ b/yt_dlp/extractor/youtube/_proto/videostreaming/sabr_seek.py
@ -0,0 +1,12 @@
+from __future__ import annotations
+
+from yt_dlp.dependencies import protobug
+
+from ..innertube import SeekSource
+
+
+@protobug.message
+class SabrSeek:
+    seek_time_ticks: protobug.Int32 = protobug.field(1)
+    timescale: protobug.Int32 = protobug.field(2)
+    seek_source: SeekSource | None = protobug.field(3, default=None)
--- a/yt_dlp/extractor/youtube/_proto/videostreaming/stream_protection_status.py
+++ b/yt_dlp/extractor/youtube/_proto/videostreaming/stream_protection_status.py
@ -0,0 +1,15 @@
+from __future__ import annotations
+
+from yt_dlp.dependencies import protobug
+
+
+@protobug.message
+class StreamProtectionStatus:
+
+    class Status(protobug.Enum, strict=False):
+        OK = 1
+        ATTESTATION_PENDING = 2
+        ATTESTATION_REQUIRED = 3
+
+    status: Status | None = protobug.field(1, default=None)
+    max_retries: protobug.Int32 | None = protobug.field(2, default=None)
--- a/yt_dlp/extractor/youtube/_proto/videostreaming/streamer_context.py
+++ b/yt_dlp/extractor/youtube/_proto/videostreaming/streamer_context.py
@ -0,0 +1,21 @@
+from __future__ import annotations
+
+from yt_dlp.dependencies import protobug
+
+from ..innertube import ClientInfo
+
+
+@protobug.message
+class SabrContext:
+    # Type and Value from a SabrContextUpdate
+    type: protobug.Int32 | None = protobug.field(1, default=None)
+    value: protobug.Bytes | None = protobug.field(2, default=None)
+
+
+@protobug.message
+class StreamerContext:
+    client_info: ClientInfo | None = protobug.field(1, default=None)
+    po_token: protobug.Bytes | None = protobug.field(2, default=None)
+    playback_cookie: protobug.Bytes | None = protobug.field(3, default=None)
+    sabr_contexts: list[SabrContext] = protobug.field(5, default_factory=list)
+    unsent_sabr_contexts: list[protobug.Int32] = protobug.field(6, default_factory=list)
--- a/yt_dlp/extractor/youtube/_proto/videostreaming/time_range.py
+++ b/yt_dlp/extractor/youtube/_proto/videostreaming/time_range.py
@ -0,0 +1,10 @@
+from __future__ import annotations
+
+from yt_dlp.dependencies import protobug
+
+
+@protobug.message
+class TimeRange:
+    start_ticks: protobug.Int64 | None = protobug.field(1, default=None)
+    duration_ticks: protobug.Int64 | None = protobug.field(2, default=None)
+    timescale: protobug.Int32 | None = protobug.field(3, default=None)
--- a/yt_dlp/extractor/youtube/_proto/videostreaming/video_playback_abr_request.py
+++ b/yt_dlp/extractor/youtube/_proto/videostreaming/video_playback_abr_request.py
@ -0,0 +1,22 @@
+from __future__ import annotations
+
+from yt_dlp.dependencies import protobug
+
+from .buffered_range import BufferedRange
+from .client_abr_state import ClientAbrState
+from .format_id import FormatId
+from .streamer_context import StreamerContext
+
+
+@protobug.message
+class VideoPlaybackAbrRequest:
+    client_abr_state: ClientAbrState = protobug.field(1, default=None)
+    initialized_format_ids: list[FormatId] = protobug.field(2, default_factory=list)
+    buffered_ranges: list[BufferedRange] = protobug.field(3, default_factory=list)
+    player_time_ms: protobug.Int64 | None = protobug.field(4, default=None)
+    video_playback_ustreamer_config: protobug.Bytes | None = protobug.field(5, default=None)
+
+    selected_audio_format_ids: list[FormatId] = protobug.field(16, default_factory=list)
+    selected_video_format_ids: list[FormatId] = protobug.field(17, default_factory=list)
+    selected_caption_format_ids: list[FormatId] = protobug.field(18, default_factory=list)
+    streamer_context: StreamerContext = protobug.field(19, default_factory=StreamerContext)
--- a/yt_dlp/extractor/youtube/_streaming/init.py
+++ b/yt_dlp/extractor/youtube/_streaming/init.py
--- a/yt_dlp/extractor/youtube/_streaming/sabr/exceptions.py
+++ b/yt_dlp/extractor/youtube/_streaming/sabr/exceptions.py
@ -0,0 +1,26 @@
+from yt_dlp.extractor.youtube._proto.videostreaming import FormatId
+from yt_dlp.utils import YoutubeDLError
+
+
+class SabrStreamConsumedError(YoutubeDLError):
+    pass
+
+
+class SabrStreamError(YoutubeDLError):
+    pass
+
+
+class MediaSegmentMismatchError(SabrStreamError):
+    def __init__(self, format_id: FormatId, expected_sequence_number: int, received_sequence_number: int):
+        super().__init__(
+            f'Segment sequence number mismatch for format {format_id}: '
+            f'expected {expected_sequence_number}, received {received_sequence_number}')
+        self.expected_sequence_number = expected_sequence_number
+        self.received_sequence_number = received_sequence_number
+
+
+class PoTokenError(SabrStreamError):
+    def __init__(self, missing=False):
+        super().__init__(
+            f'This stream requires a GVS PO Token to continue'
+            f'{" and the one provided is invalid" if not missing else ""}')
--- a/yt_dlp/extractor/youtube/_streaming/sabr/models.py
+++ b/yt_dlp/extractor/youtube/_streaming/sabr/models.py
@ -0,0 +1,97 @@
+from __future__ import annotations
+
+import dataclasses
+
+from yt_dlp.extractor.youtube._proto.videostreaming import FormatId
+from yt_dlp.extractor.youtube.pot._provider import IEContentProviderLogger
+
+
+@dataclasses.dataclass
+class Segment:
+    format_id: FormatId
+    is_init_segment: bool = False
+    duration_ms: int = 0
+    start_ms: int = 0
+    start_data_range: int = 0
+    sequence_number: int = 0
+    content_length: int | None = None
+    content_length_estimated: bool = False
+    initialized_format: InitializedFormat = None
+    # Whether duration_ms is an estimate
+    duration_estimated: bool = False
+    # Whether we should discard the segment data
+    discard: bool = False
+    # Whether the segment has already been consumed.
+    # `discard` should be set to True if this is the case.
+    consumed: bool = False
+    received_data_length: int = 0
+    sequence_lmt: int | None = None
+
+
+@dataclasses.dataclass
+class ConsumedRange:
+    start_sequence_number: int
+    end_sequence_number: int
+    start_time_ms: int
+    duration_ms: int
+
+
+@dataclasses.dataclass
+class InitializedFormat:
+    format_id: FormatId
+    video_id: str
+    format_selector: FormatSelector | None = None
+    duration_ms: int = 0
+    end_time_ms: int = 0
+    mime_type: str = None
+    # Current segment in the sequence. Set to None to break the sequence and allow a seek.
+    current_segment: Segment | None = None
+    init_segment: Segment | None | bool = None
+    consumed_ranges: list[ConsumedRange] = dataclasses.field(default_factory=list)
+    total_segments: int = None
+    # Whether we should discard any data received for this format
+    discard: bool = False
+    sequence_lmt: int | None = None
+
+
+SabrLogger = IEContentProviderLogger
+
+
+@dataclasses.dataclass
+class FormatSelector:
+    display_name: str
+    format_ids: list[FormatId] = dataclasses.field(default_factory=list)
+    discard_media: bool = False
+
+    def match(self, format_id: FormatId = None, **kwargs) -> bool:
+        return format_id in self.format_ids
+
+
+@dataclasses.dataclass
+class AudioSelector(FormatSelector):
+
+    def match(self, format_id: FormatId = None, mime_type: str | None = None, **kwargs) -> bool:
+        return (
+            super().match(format_id, mime_type=mime_type, **kwargs)
+            or (not self.format_ids and mime_type and mime_type.lower().startswith('audio'))
+        )
+
+
+@dataclasses.dataclass
+class VideoSelector(FormatSelector):
+
+    def match(self, format_id: FormatId = None, mime_type: str | None = None, **kwargs) -> bool:
+        return (
+            super().match(format_id, mime_type=mime_type, **kwargs)
+            or (not self.format_ids and mime_type and mime_type.lower().startswith('video'))
+        )
+
+
+@dataclasses.dataclass
+class CaptionSelector(FormatSelector):
+
+    def match(self, format_id: FormatId = None, mime_type: str | None = None, **kwargs) -> bool:
+        return (
+            super().match(format_id, mime_type=mime_type, **kwargs)
+            or (not self.format_ids and mime_type and mime_type.lower().startswith('text'))
+        )
--- a/yt_dlp/extractor/youtube/_streaming/sabr/part.py
+++ b/yt_dlp/extractor/youtube/_streaming/sabr/part.py
@ -0,0 +1,92 @@
+import dataclasses
+import enum
+
+from yt_dlp.extractor.youtube._proto.videostreaming import FormatId
+
+from .models import FormatSelector
+
+
+@dataclasses.dataclass
+class SabrPart:
+    pass
+
+
+@dataclasses.dataclass
+class MediaSegmentInitSabrPart(SabrPart):
+    format_selector: FormatSelector
+    format_id: FormatId
+    sequence_number: int = None
+    is_init_segment: bool = False
+    total_segments: int = None
+    start_time_ms: int = None
+    player_time_ms: int = None
+    duration_ms: int = None
+    duration_estimated: bool = False
+    start_bytes: int = None
+    content_length: int = None
+    content_length_estimated: bool = False
+
+
+@dataclasses.dataclass
+class MediaSegmentDataSabrPart(SabrPart):
+    format_selector: FormatSelector
+    format_id: FormatId
+    sequence_number: int = None
+    is_init_segment: bool = False
+    total_segments: int = None
+    data: bytes = b''
+    content_length: int = None
+    segment_start_bytes: int = None
+
+
+@dataclasses.dataclass
+class MediaSegmentEndSabrPart(SabrPart):
+    format_selector: FormatSelector
+    format_id: FormatId
+    sequence_number: int = None
+    is_init_segment: bool = False
+    total_segments: int = None
+
+
+@dataclasses.dataclass
+class FormatInitializedSabrPart(SabrPart):
+    format_id: FormatId
+    format_selector: FormatSelector
+
+
+@dataclasses.dataclass
+class PoTokenStatusSabrPart(SabrPart):
+    class PoTokenStatus(enum.Enum):
+        OK = enum.auto()                          # PO Token is provided and valid
+        MISSING = enum.auto()                     # PO Token is not provided, and is required. A PO Token should be provided ASAP
+        INVALID = enum.auto()                     # PO Token is provided, but is invalid. A new one should be generated ASAP
+        PENDING = enum.auto()                     # PO Token is provided, but probably only a cold start token. A full PO Token should be provided ASAP
+        NOT_REQUIRED = enum.auto()                # PO Token is not provided, and is not required
+        PENDING_MISSING = enum.auto()             # PO Token is not provided, but is pending. A full PO Token should be (probably) provided ASAP
+
+    status: PoTokenStatus
+
+
+@dataclasses.dataclass
+class RefreshPlayerResponseSabrPart(SabrPart):
+
+    class Reason(enum.Enum):
+        UNKNOWN = enum.auto()
+        SABR_URL_EXPIRY = enum.auto()
+        SABR_RELOAD_PLAYER_RESPONSE = enum.auto()
+
+    reason: Reason
+    reload_playback_token: str = None
+
+
+@dataclasses.dataclass
+class MediaSeekSabrPart(SabrPart):
+    # Lets the consumer know the media sequence for a format may change
+    class Reason(enum.Enum):
+        UNKNOWN = enum.auto()
+        SERVER_SEEK = enum.auto()  # SABR_SEEK from server
+        CONSUMED_SEEK = enum.auto()  # Seeking as next fragment is already buffered
+
+    reason: Reason
+    format_id: FormatId
+    format_selector: FormatSelector
--- a/yt_dlp/extractor/youtube/_streaming/sabr/processor.py
+++ b/yt_dlp/extractor/youtube/_streaming/sabr/processor.py
@ -0,0 +1,671 @@
+from __future__ import annotations
+
+import base64
+import io
+import math
+
+from yt_dlp.extractor.youtube._proto.innertube import ClientInfo, NextRequestPolicy
+from yt_dlp.extractor.youtube._proto.videostreaming import (
+    BufferedRange,
+    ClientAbrState,
+    FormatInitializationMetadata,
+    LiveMetadata,
+    MediaHeader,
+    SabrContext,
+    SabrContextSendingPolicy,
+    SabrContextUpdate,
+    SabrSeek,
+    StreamerContext,
+    StreamProtectionStatus,
+    TimeRange,
+    VideoPlaybackAbrRequest,
+)
+
+from .exceptions import MediaSegmentMismatchError, SabrStreamError
+from .models import (
+    AudioSelector,
+    CaptionSelector,
+    ConsumedRange,
+    InitializedFormat,
+    SabrLogger,
+    Segment,
+    VideoSelector,
+)
+from .part import (
+    FormatInitializedSabrPart,
+    MediaSeekSabrPart,
+    MediaSegmentDataSabrPart,
+    MediaSegmentEndSabrPart,
+    MediaSegmentInitSabrPart,
+    PoTokenStatusSabrPart,
+)
+from .utils import ticks_to_ms
+
+
+class ProcessMediaEndResult:
+    def __init__(self, sabr_part: MediaSegmentEndSabrPart = None, is_new_segment: bool = False):
+        self.is_new_segment = is_new_segment
+        self.sabr_part = sabr_part
+
+
+class ProcessMediaResult:
+    def __init__(self, sabr_part: MediaSegmentDataSabrPart = None):
+        self.sabr_part = sabr_part
+
+
+class ProcessMediaHeaderResult:
+    def __init__(self, sabr_part: MediaSegmentInitSabrPart | None = None):
+        self.sabr_part = sabr_part
+
+
+class ProcessLiveMetadataResult:
+    def __init__(self, seek_sabr_parts: list[MediaSeekSabrPart] | None = None):
+        self.seek_sabr_parts = seek_sabr_parts or []
+
+
+class ProcessStreamProtectionStatusResult:
+    def __init__(self, sabr_part: PoTokenStatusSabrPart | None = None):
+        self.sabr_part = sabr_part
+
+
+class ProcessFormatInitializationMetadataResult:
+    def __init__(self, sabr_part: FormatInitializedSabrPart | None = None):
+        self.sabr_part = sabr_part
+
+
+class ProcessSabrSeekResult:
+    def __init__(self, seek_sabr_parts: list[MediaSeekSabrPart] | None = None):
+        self.seek_sabr_parts = seek_sabr_parts or []
+
+
+class SabrProcessor:
+    """
+    SABR Processor
+
+    This handles core SABR protocol logic, independent of requests.
+    """
+
+    def __init__(
+        self,
+        logger: SabrLogger,
+        video_playback_ustreamer_config: str,
+        client_info: ClientInfo,
+        audio_selection: AudioSelector | None = None,
+        video_selection: VideoSelector | None = None,
+        caption_selection: CaptionSelector | None = None,
+        live_segment_target_duration_sec: int | None = None,
+        live_segment_target_duration_tolerance_ms: int | None = None,
+        start_time_ms: int | None = None,
+        po_token: str | None = None,
+        live_end_wait_sec: int | None = None,
+        live_end_segment_tolerance: int | None = None,
+        post_live: bool = False,
+        video_id: str | None = None,
+    ):
+
+        self.logger = logger
+
+        self.video_playback_ustreamer_config = video_playback_ustreamer_config
+        self.po_token = po_token
+        self.client_info = client_info
+        self.live_segment_target_duration_sec = live_segment_target_duration_sec or 5
+        self.live_segment_target_duration_tolerance_ms = live_segment_target_duration_tolerance_ms or 100
+        if self.live_segment_target_duration_tolerance_ms >= (self.live_segment_target_duration_sec * 1000) / 2:
+            raise ValueError(
+                'live_segment_target_duration_tolerance_ms must be less than '
+                'half of live_segment_target_duration_sec in milliseconds',
+            )
+        self.start_time_ms = start_time_ms or 0
+        if self.start_time_ms < 0:
+            raise ValueError('start_time_ms must be greater than or equal to 0')
+
+        self.live_end_wait_sec = live_end_wait_sec or max(10, 3 * self.live_segment_target_duration_sec)
+        self.live_end_segment_tolerance = live_end_segment_tolerance or 10
+        self.post_live = post_live
+        self._is_live = False
+        self.video_id = video_id
+
+        self._audio_format_selector = audio_selection
+        self._video_format_selector = video_selection
+        self._caption_format_selector = caption_selection
+
+        # IMPORTANT: initialized formats is assumed to contain only ACTIVE formats
+        self.initialized_formats: dict[str, InitializedFormat] = {}
+        self.stream_protection_status: StreamProtectionStatus.Status | None = None
+
+        self.partial_segments: dict[int, Segment] = {}
+        self.total_duration_ms = None
+        self.selected_audio_format_ids = []
+        self.selected_video_format_ids = []
+        self.selected_caption_format_ids = []
+        self.next_request_policy: NextRequestPolicy | None = None
+        self.live_metadata: LiveMetadata | None = None
+        self.client_abr_state: ClientAbrState
+        self.sabr_contexts_to_send: set[int] = set()
+        self.sabr_context_updates: dict[int, SabrContextUpdate] = {}
+        self._initialize_cabr_state()
+
+    @property
+    def is_live(self):
+        return bool(
+            self.live_metadata
+            or self._is_live,
+        )
+
+    @is_live.setter
+    def is_live(self, value: bool):
+        self._is_live = value
+
+    def _initialize_cabr_state(self):
+        enabled_track_types_bitfield = 0  # Audio+Video
+        if not self._video_format_selector:
+            enabled_track_types_bitfield = 1  # Audio only
+            self._video_format_selector = VideoSelector(display_name='video_ignore', discard_media=True)
+
+        if self._caption_format_selector:
+            # SABR does not support caption-only or audio+captions only - can only get audio+video with captions
+            # If audio or video is not selected, the tracks will be initialized but marked as buffered.
+            enabled_track_types_bitfield = 7
+
+        # SABR does not support video-only, so we need to discard the audio track received.
+        # We need a selector as the server sometimes does not like it
+        # if we haven't initialized an audio format (e.g. livestreams).
+        if not self._audio_format_selector:
+            self._audio_format_selector = AudioSelector(display_name='audio_ignore', discard_media=True)
+
+        if not self._caption_format_selector:
+            self._caption_format_selector = CaptionSelector(display_name='caption_ignore', discard_media=True)
+
+        self.selected_audio_format_ids = self._audio_format_selector.format_ids
+        self.selected_video_format_ids = self._video_format_selector.format_ids
+        self.selected_caption_format_ids = self._caption_format_selector.format_ids
+
+        self.logger.debug(f'Starting playback at: {self.start_time_ms}ms')
+        self.client_abr_state = ClientAbrState(
+            player_time_ms=self.start_time_ms,
+            enabled_track_types_bitfield=enabled_track_types_bitfield)
+
+    def match_format_selector(self, format_init_metadata):
+        for format_selector in (self._video_format_selector, self._audio_format_selector, self._caption_format_selector):
+            if not format_selector:
+                continue
+            if format_selector.match(format_id=format_init_metadata.format_id, mime_type=format_init_metadata.mime_type):
+                return format_selector
+        return None
+
+    def process_media_header(self, media_header: MediaHeader) -> ProcessMediaHeaderResult:
+        if media_header.video_id and self.video_id and media_header.video_id != self.video_id:
+            raise SabrStreamError(
+                f'Received unexpected MediaHeader for video'
+                f' {media_header.video_id} (expecting {self.video_id})')
+
+        if not media_header.format_id:
+            raise SabrStreamError(f'Format ID not found in MediaHeader (media_header={media_header})')
+
+        # Guard. This should not happen, except if we don't clear partial segments
+        if media_header.header_id in self.partial_segments:
+            raise SabrStreamError(f'Header ID {media_header.header_id} already exists')
+
+        result = ProcessMediaHeaderResult()
+
+        initialized_format = self.initialized_formats.get(str(media_header.format_id))
+        if not initialized_format:
+            self.logger.debug(f'Initialized format not found for {media_header.format_id}')
+            return result
+
+        if media_header.compression:
+            # Unknown when this is used, but it is not supported currently
+            raise SabrStreamError(f'Compression not supported in MediaHeader (media_header={media_header})')
+
+        sequence_number, is_init_segment = media_header.sequence_number, media_header.is_init_segment
+        if sequence_number is None and not media_header.is_init_segment:
+            raise SabrStreamError(f'Sequence number not found in MediaHeader (media_header={media_header})')
+
+        initialized_format.sequence_lmt = media_header.sequence_lmt
+
+        # Need to keep track of if we discard due to be consumed or not
+        # for processing down the line (MediaEnd)
+        consumed = False
+        discard = initialized_format.discard
+
+        # Guard: Check if sequence number is within any existing consumed range
+        # The server should not send us any segments that are already consumed
+        # However, if retrying a request, we may get the same segment again
+        if not is_init_segment and any(
+            cr.start_sequence_number <= sequence_number <= cr.end_sequence_number
+            for cr in initialized_format.consumed_ranges
+        ):
+            self.logger.debug(f'{initialized_format.format_id} segment {sequence_number} already consumed, marking segment as consumed')
+            consumed = True
+
+        # Validate that the segment is in order.
+        # Note: If the format is to be discarded, we do not care about the order
+        #  and can expect uncommanded seeks as the consumer does not know about it.
+        # Note: previous segment should never be an init segment.
+        previous_segment = initialized_format.current_segment
+        if (
+            previous_segment and not is_init_segment
+            and not previous_segment.discard and not discard and not consumed
+            and sequence_number != previous_segment.sequence_number + 1
+        ):
+            # Bail out as the segment is not in order when it is expected to be
+            raise MediaSegmentMismatchError(
+                expected_sequence_number=previous_segment.sequence_number + 1,
+                received_sequence_number=sequence_number,
+                format_id=media_header.format_id)
+
+        if initialized_format.init_segment and is_init_segment:
+            self.logger.debug(
+                f'Init segment {sequence_number} already seen for format {initialized_format.format_id}, marking segment as consumed')
+            consumed = True
+
+        time_range = media_header.time_range
+        start_ms = media_header.start_ms or (time_range and ticks_to_ms(time_range.start_ticks, time_range.timescale)) or 0
+
+        # Calculate duration of this segment
+        # For videos, either duration_ms or time_range should be present
+        # For live streams, calculate segment duration based on live metadata target segment duration
+        actual_duration_ms = (
+            media_header.duration_ms
+            or (time_range and ticks_to_ms(time_range.duration_ticks, time_range.timescale)))
+
+        estimated_duration_ms = None
+        if self.is_live:
+            # Underestimate the duration of the segment slightly as
+            # the real duration may be slightly shorter than the target duration.
+            estimated_duration_ms = (self.live_segment_target_duration_sec * 1000) - self.live_segment_target_duration_tolerance_ms
+        elif is_init_segment:
+            estimated_duration_ms = 0
+
+        duration_ms = actual_duration_ms or estimated_duration_ms
+
+        estimated_content_length = None
+        if self.is_live and media_header.content_length is None and media_header.bitrate_bps is not None:
+            estimated_content_length = math.ceil(media_header.bitrate_bps * (estimated_duration_ms / 1000))
+
+        # Guard: Bail out if we cannot determine the duration, which we need to progress.
+        if duration_ms is None:
+            raise SabrStreamError(f'Cannot determine duration of segment {sequence_number} (media_header={media_header})')
+
+        segment = Segment(
+            format_id=media_header.format_id,
+            is_init_segment=is_init_segment,
+            duration_ms=duration_ms,
+            start_data_range=media_header.start_data_range,
+            sequence_number=sequence_number,
+            content_length=media_header.content_length or estimated_content_length,
+            content_length_estimated=estimated_content_length is not None,
+            start_ms=start_ms,
+            initialized_format=initialized_format,
+            duration_estimated=not actual_duration_ms,
+            discard=discard or consumed,
+            consumed=consumed,
+            sequence_lmt=media_header.sequence_lmt,
+        )
+
+        self.partial_segments[media_header.header_id] = segment
+
+        if not segment.discard:
+            result.sabr_part = MediaSegmentInitSabrPart(
+                format_selector=segment.initialized_format.format_selector,
+                format_id=segment.format_id,
+                player_time_ms=self.client_abr_state.player_time_ms,
+                sequence_number=segment.sequence_number,
+                total_segments=segment.initialized_format.total_segments,
+                duration_ms=segment.duration_ms,
+                start_bytes=segment.start_data_range,
+                start_time_ms=segment.start_ms,
+                is_init_segment=segment.is_init_segment,
+                content_length=segment.content_length,
+                content_length_estimated=segment.content_length_estimated,
+            )
+
+        self.logger.trace(
+            f'Initialized Media Header {media_header.header_id} for sequence {sequence_number}. Segment: {segment}')
+
+        return result
+
+    def process_media(self, header_id: int, content_length: int, data: io.BufferedIOBase) -> ProcessMediaResult:
+        result = ProcessMediaResult()
+        segment = self.partial_segments.get(header_id)
+        if not segment:
+            self.logger.debug(f'Header ID {header_id} not found')
+            return result
+
+        segment_start_bytes = segment.received_data_length
+        segment.received_data_length += content_length
+
+        if not segment.discard:
+            result.sabr_part = MediaSegmentDataSabrPart(
+                format_selector=segment.initialized_format.format_selector,
+                format_id=segment.format_id,
+                sequence_number=segment.sequence_number,
+                is_init_segment=segment.is_init_segment,
+                total_segments=segment.initialized_format.total_segments,
+                data=data.read(),
+                content_length=content_length,
+                segment_start_bytes=segment_start_bytes,
+            )
+
+        return result
+
+    def process_media_end(self, header_id: int) -> ProcessMediaEndResult:
+        result = ProcessMediaEndResult()
+        segment = self.partial_segments.pop(header_id, None)
+        if not segment:
+            # Should only happen due to server issue,
+            # or we have an uninitialized format (which itself should not happen)
+            self.logger.warning(f'Received a MediaEnd for an unknown or already finished header ID {header_id}')
+            return result
+
+        self.logger.trace(
+            f'MediaEnd for {segment.format_id} (sequence {segment.sequence_number}, data length = {segment.received_data_length})')
+
+        if segment.content_length is not None and segment.received_data_length != segment.content_length:
+            if segment.content_length_estimated:
+                self.logger.trace(
+                    f'Content length for {segment.format_id} (sequence {segment.sequence_number}) was estimated, '
+                    f'estimated {segment.content_length} bytes, got {segment.received_data_length} bytes')
+            else:
+                raise SabrStreamError(
+                    f'Content length mismatch for {segment.format_id} (sequence {segment.sequence_number}): '
+                    f'expected {segment.content_length} bytes, got {segment.received_data_length} bytes',
+                )
+
+        # Only count received segments as new segments if they are not discarded (consumed)
+        # or it was part of a format that was discarded (but not consumed).
+        # The latter can happen if the format is to be discarded but was not marked as fully consumed.
+        if not segment.discard or (segment.initialized_format.discard and not segment.consumed):
+            result.is_new_segment = True
+
+        # Return the segment here instead of during MEDIA part(s) because:
+        # 1. We can validate that we received the correct data length
+        # 2. In the case of a retry during segment media, the partial data is not sent to the consumer
+        if not segment.discard:
+            # This needs to be yielded AFTER we have processed the segment
+            # So the consumer can see the updated consumed ranges and use them for e.g. syncing between concurrent streams
+            result.sabr_part = MediaSegmentEndSabrPart(
+                format_selector=segment.initialized_format.format_selector,
+                format_id=segment.format_id,
+                sequence_number=segment.sequence_number,
+                is_init_segment=segment.is_init_segment,
+                total_segments=segment.initialized_format.total_segments,
+            )
+        else:
+            self.logger.trace(f'Discarding media for {segment.initialized_format.format_id}')
+
+        if segment.is_init_segment:
+            segment.initialized_format.init_segment = segment
+            # Do not create a consumed range for init segments
+            return result
+
+        if segment.initialized_format.current_segment and self.is_live:
+            previous_segment = segment.initialized_format.current_segment
+            self.logger.trace(
+                f'Previous segment {previous_segment.sequence_number} for format {segment.format_id} '
+                f'estimated duration difference from this segment ({segment.sequence_number}): {segment.start_ms - (previous_segment.start_ms + previous_segment.duration_ms)}ms')
+
+        segment.initialized_format.current_segment = segment
+
+        # Try to find a consumed range for this segment in sequence
+        consumed_range = next(
+            (cr for cr in segment.initialized_format.consumed_ranges if cr.end_sequence_number == segment.sequence_number - 1),
+            None,
+        )
+
+        if not consumed_range and any(
+            cr.start_sequence_number <= segment.sequence_number <= cr.end_sequence_number
+            for cr in segment.initialized_format.consumed_ranges
+        ):
+            # Segment is already consumed, do not create a new consumed range. It was probably discarded.
+            # This can be expected to happen in the case of video-only, where we discard the audio track (and mark it as entirely buffered)
+            # We still want to create/update consumed range for discarded media IF it is not already consumed
+            self.logger.debug(f'{segment.format_id} segment {segment.sequence_number} already consumed, not creating or updating consumed range (discard={segment.discard})')
+            return result
+
+        if not consumed_range:
+            # Create a new consumed range starting from this segment
+            segment.initialized_format.consumed_ranges.append(ConsumedRange(
+                start_time_ms=segment.start_ms,
+                duration_ms=segment.duration_ms,
+                start_sequence_number=segment.sequence_number,
+                end_sequence_number=segment.sequence_number,
+            ))
+            self.logger.debug(f'Created new consumed range for {segment.initialized_format.format_id} {segment.initialized_format.consumed_ranges[-1]}')
+            return result
+
+        # Update the existing consumed range to include this segment
+        consumed_range.end_sequence_number = segment.sequence_number
+        consumed_range.duration_ms = (segment.start_ms - consumed_range.start_time_ms) + segment.duration_ms
+
+        # TODO: Conduct a seek on consumed ranges
+
+        return result
+
+    def process_live_metadata(self, live_metadata: LiveMetadata) -> ProcessLiveMetadataResult:
+        self.live_metadata = live_metadata
+        if self.live_metadata.head_sequence_time_ms:
+            self.total_duration_ms = self.live_metadata.head_sequence_time_ms
+
+        # If we have a head sequence number, we need to update the total sequences for each initialized format
+        # For livestreams, it is not available in the format initialization metadata
+        if self.live_metadata.head_sequence_number:
+            for izf in self.initialized_formats.values():
+                izf.total_segments = self.live_metadata.head_sequence_number
+
+        result = ProcessLiveMetadataResult()
+
+        # If the current player time is less than the min dvr time, simulate a server seek to the min dvr time.
+        # The server SHOULD send us a SABR_SEEK part in this case, but it does not always happen (e.g. ANDROID_VR)
+        # The server SHOULD NOT send us segments before the min dvr time, so we should assume that the player time is correct.
+        min_seekable_time_ms = ticks_to_ms(self.live_metadata.min_seekable_time_ticks, self.live_metadata.min_seekable_timescale)
+        if min_seekable_time_ms is not None and self.client_abr_state.player_time_ms < min_seekable_time_ms:
+            self.logger.debug(f'Player time {self.client_abr_state.player_time_ms} is less than min seekable time {min_seekable_time_ms}, simulating server seek')
+            self.client_abr_state.player_time_ms = min_seekable_time_ms
+
+            for izf in self.initialized_formats.values():
+                izf.current_segment = None  # Clear the current segment as we expect segments to no longer be in order.
+                result.seek_sabr_parts.append(MediaSeekSabrPart(
+                    reason=MediaSeekSabrPart.Reason.SERVER_SEEK,
+                    format_id=izf.format_id,
+                    format_selector=izf.format_selector,
+                ))
+
+        return result
+
+    def process_stream_protection_status(self, stream_protection_status: StreamProtectionStatus) -> ProcessStreamProtectionStatusResult:
+        self.stream_protection_status = stream_protection_status.status
+        status = stream_protection_status.status
+        po_token = self.po_token
+
+        if status == StreamProtectionStatus.Status.OK:
+            result_status = (
+                PoTokenStatusSabrPart.PoTokenStatus.OK if po_token
+                else PoTokenStatusSabrPart.PoTokenStatus.NOT_REQUIRED
+            )
+        elif status == StreamProtectionStatus.Status.ATTESTATION_PENDING:
+            result_status = (
+                PoTokenStatusSabrPart.PoTokenStatus.PENDING if po_token
+                else PoTokenStatusSabrPart.PoTokenStatus.PENDING_MISSING
+            )
+        elif status == StreamProtectionStatus.Status.ATTESTATION_REQUIRED:
+            result_status = (
+                PoTokenStatusSabrPart.PoTokenStatus.INVALID if po_token
+                else PoTokenStatusSabrPart.PoTokenStatus.MISSING
+            )
+        else:
+            result_status = None
+
+        sabr_part = PoTokenStatusSabrPart(status=result_status) if result_status is not None else None
+        return ProcessStreamProtectionStatusResult(sabr_part)
+
+    def process_format_initialization_metadata(self, format_init_metadata: FormatInitializationMetadata) -> ProcessFormatInitializationMetadataResult:
+        result = ProcessFormatInitializationMetadataResult()
+        if str(format_init_metadata.format_id) in self.initialized_formats:
+            self.logger.trace(f'Format {format_init_metadata.format_id} already initialized')
+            return result
+
+        if format_init_metadata.video_id and self.video_id and format_init_metadata.video_id != self.video_id:
+            raise SabrStreamError(
+                f'Received unexpected Format Initialization Metadata for video'
+                f' {format_init_metadata.video_id} (expecting {self.video_id})')
+
+        format_selector = self.match_format_selector(format_init_metadata)
+        if not format_selector:
+            # Should not happen. If we ignored the format the server may refuse to send us any more data
+            raise SabrStreamError(f'Received format {format_init_metadata.format_id} but it does not match any format selector')
+
+        # Guard: Check if the format selector is already in use by another initialized format.
+        # This can happen when the server changes the format to use (e.g. changing quality).
+        #
+        # Changing a format will require adding some logic to handle inactive formats.
+        # Given we only provide one FormatId currently, and this should not occur in this case,
+        # we will mark this as not currently supported and bail.
+        for izf in self.initialized_formats.values():
+            if izf.format_selector is format_selector:
+                raise SabrStreamError('Server changed format. Changing formats is not currently supported')
+
+        duration_ms = ticks_to_ms(format_init_metadata.duration_timescale, format_init_metadata.duration_ticks)
+
+        total_segments = format_init_metadata.total_segments
+        if not total_segments and self.live_metadata and self.live_metadata.head_sequence_number:
+            total_segments = self.live_metadata.head_sequence_number
+
+        initialized_format = InitializedFormat(
+            format_id=format_init_metadata.format_id,
+            duration_ms=duration_ms,
+            end_time_ms=format_init_metadata.end_time_ms,
+            mime_type=format_init_metadata.mime_type,
+            video_id=format_init_metadata.video_id,
+            format_selector=format_selector,
+            total_segments=total_segments,
+            discard=format_selector.discard_media,
+        )
+        self.total_duration_ms = max(self.total_duration_ms or 0, format_init_metadata.end_time_ms or 0, duration_ms or 0)
+
+        if initialized_format.discard:
+            # Mark the entire format as buffered into oblivion if we plan to discard all media.
+            # This stops the server sending us any more data for this format.
+            # Note: Using JS_MAX_SAFE_INTEGER but could use any maximum value as long as the server accepts it.
+            initialized_format.consumed_ranges = [ConsumedRange(
+                start_time_ms=0,
+                duration_ms=(2**53) - 1,
+                start_sequence_number=0,
+                end_sequence_number=(2**53) - 1,
+            )]
+
+        self.initialized_formats[str(format_init_metadata.format_id)] = initialized_format
+        self.logger.debug(f'Initialized Format: {initialized_format}')
+
+        if not initialized_format.discard:
+            result.sabr_part = FormatInitializedSabrPart(
+                format_id=format_init_metadata.format_id,
+                format_selector=format_selector,
+            )
+
+        return ProcessFormatInitializationMetadataResult(sabr_part=result.sabr_part)
+
+    def process_next_request_policy(self, next_request_policy: NextRequestPolicy):
+        self.next_request_policy = next_request_policy
+        self.logger.trace(f'Registered new NextRequestPolicy: {self.next_request_policy}')
+
+    def process_sabr_seek(self, sabr_seek: SabrSeek) -> ProcessSabrSeekResult:
+        seek_to = ticks_to_ms(sabr_seek.seek_time_ticks, sabr_seek.timescale)
+        if seek_to is None:
+            raise SabrStreamError(f'Server sent a SabrSeek part that is missing required seek data: {sabr_seek}')
+        self.logger.debug(f'Seeking to {seek_to}ms')
+        self.client_abr_state.player_time_ms = seek_to
+
+        result = ProcessSabrSeekResult()
+
+        # Clear latest segment of each initialized format
+        #  as we expect them to no longer be in order.
+        for initialized_format in self.initialized_formats.values():
+            initialized_format.current_segment = None
+            result.seek_sabr_parts.append(MediaSeekSabrPart(
+                reason=MediaSeekSabrPart.Reason.SERVER_SEEK,
+                format_id=initialized_format.format_id,
+                format_selector=initialized_format.format_selector,
+            ))
+        return result
+
+    def process_sabr_context_update(self, sabr_ctx_update: SabrContextUpdate):
+        if not (sabr_ctx_update.type and sabr_ctx_update.value and sabr_ctx_update.write_policy):
+            self.logger.warning('Received an invalid SabrContextUpdate, ignoring')
+            return
+
+        if (
+            sabr_ctx_update.write_policy == SabrContextUpdate.SabrContextWritePolicy.SABR_CONTEXT_WRITE_POLICY_KEEP_EXISTING
+            and sabr_ctx_update.type in self.sabr_context_updates
+        ):
+            self.logger.debug(
+                'Received a SABR Context Update with write_policy=KEEP_EXISTING'
+                'matching an existing SABR Context Update. Ignoring update')
+            return
+
+        self.logger.warning(
+            'Received a SABR Context Update. YouTube is likely trying to force ads on the client. '
+            'This may cause issues with playback.')
+
+        self.sabr_context_updates[sabr_ctx_update.type] = sabr_ctx_update
+        if sabr_ctx_update.send_by_default is True:
+            self.sabr_contexts_to_send.add(sabr_ctx_update.type)
+        self.logger.debug(f'Registered SabrContextUpdate {sabr_ctx_update}')
+
+    def process_sabr_context_sending_policy(self, sabr_ctx_sending_policy: SabrContextSendingPolicy):
+        for start_type in sabr_ctx_sending_policy.start_policy:
+            if start_type not in self.sabr_context_updates:
+                self.logger.debug(f'Server requested to enable SABR Context Update for type {start_type}')
+                self.sabr_contexts_to_send.add(start_type)
+
+        for stop_type in sabr_ctx_sending_policy.stop_policy:
+            if stop_type in self.sabr_contexts_to_send:
+                self.logger.debug(f'Server requested to disable SABR Context Update for type {stop_type}')
+                self.sabr_contexts_to_send.remove(stop_type)
+
+        for discard_type in sabr_ctx_sending_policy.discard_policy:
+            if discard_type in self.sabr_context_updates:
+                self.logger.debug(f'Server requested to discard SABR Context Update for type {discard_type}')
+                self.sabr_context_updates.pop(discard_type, None)
+
+
+def build_vpabr_request(processor: SabrProcessor):
+    return VideoPlaybackAbrRequest(
+        client_abr_state=processor.client_abr_state,
+        selected_video_format_ids=processor.selected_video_format_ids,
+        selected_audio_format_ids=processor.selected_audio_format_ids,
+        selected_caption_format_ids=processor.selected_caption_format_ids,
+        initialized_format_ids=[
+            initialized_format.format_id for initialized_format in processor.initialized_formats.values()
+        ],
+        video_playback_ustreamer_config=base64.urlsafe_b64decode(processor.video_playback_ustreamer_config),
+        streamer_context=StreamerContext(
+            po_token=base64.urlsafe_b64decode(processor.po_token) if processor.po_token is not None else None,
+            playback_cookie=processor.next_request_policy.playback_cookie if processor.next_request_policy is not None else None,
+            client_info=processor.client_info,
+            sabr_contexts=[
+                SabrContext(context.type, context.value)
+                for context in processor.sabr_context_updates.values()
+                if context.type in processor.sabr_contexts_to_send
+            ],
+            unsent_sabr_contexts=[
+                context_type for context_type in processor.sabr_contexts_to_send
+                if context_type not in processor.sabr_context_updates
+            ],
+        ),
+        buffered_ranges=[
+            BufferedRange(
+                format_id=initialized_format.format_id,
+                start_segment_index=cr.start_sequence_number,
+                end_segment_index=cr.end_sequence_number,
+                start_time_ms=cr.start_time_ms,
+                duration_ms=cr.duration_ms,
+                time_range=TimeRange(
+                    start_ticks=cr.start_time_ms,
+                    duration_ticks=cr.duration_ms,
+                    timescale=1000,
+                ),
+            ) for initialized_format in processor.initialized_formats.values()
+            for cr in initialized_format.consumed_ranges
+        ],
+    )
--- a/yt_dlp/extractor/youtube/_streaming/sabr/stream.py
+++ b/yt_dlp/extractor/youtube/_streaming/sabr/stream.py
@ -0,0 +1,813 @@
+from __future__ import annotations
+
+import base64
+import dataclasses
+import datetime as dt
+import math
+import time
+import typing
+import urllib.parse
+
+from yt_dlp.dependencies import protobug
+from yt_dlp.extractor.youtube._proto import unknown_fields
+from yt_dlp.extractor.youtube._proto.innertube import ClientInfo, NextRequestPolicy
+from yt_dlp.extractor.youtube._proto.videostreaming import (
+    FormatInitializationMetadata,
+    LiveMetadata,
+    MediaHeader,
+    ReloadPlayerResponse,
+    SabrContextSendingPolicy,
+    SabrContextUpdate,
+    SabrError,
+    SabrRedirect,
+    SabrSeek,
+    StreamProtectionStatus,
+)
+from yt_dlp.networking import Request, Response
+from yt_dlp.networking.exceptions import HTTPError, TransportError
+from yt_dlp.utils import RetryManager, int_or_none, parse_qs, str_or_none, traverse_obj
+
+from .exceptions import MediaSegmentMismatchError, PoTokenError, SabrStreamConsumedError, SabrStreamError
+from .models import AudioSelector, CaptionSelector, SabrLogger, VideoSelector
+from .part import (
+    MediaSeekSabrPart,
+    RefreshPlayerResponseSabrPart,
+)
+from .processor import SabrProcessor, build_vpabr_request
+from .utils import broadcast_id_from_url, get_cr_chain, next_gvs_fallback_url
+from ..ump import UMPDecoder, UMPPart, UMPPartId, read_varint
+
+
+class SabrStream:
+
+    """
+
+    A YouTube SABR (Server Adaptive Bit Rate) client implementation designed for downloading streams and videos.
+
+    It presents an iterator (iter_parts) that yields the next available segments and other metadata.
+
+    Parameters:
+    @param urlopen: A callable that takes a Request and returns a Response. Raises TransportError or HTTPError on failure.
+    @param logger: The logger.
+    @param server_abr_streaming_url: SABR streaming URL.
+    @param video_playback_ustreamer_config: The base64url encoded ustreamer config.
+    @param client_info: The Innertube client info.
+    @param audio_selection: The audio format selector to use for audio.
+    @param video_selection: The video format selector to use for video.
+    @param caption_selection: The caption format selector to use for captions.
+    @param live_segment_target_duration_sec: The target duration of live segments in seconds.
+    @param live_segment_target_duration_tolerance_ms: The tolerance to accept for estimated duration of live segment in milliseconds.
+    @param start_time_ms: The time in milliseconds to start playback from.
+    @param po_token: Initial GVS PO Token.
+    @param http_retries: The maximum number of times to retry a request before failing.
+    @param pot_retries: The maximum number of times to retry PO Token errors before failing.
+    @param host_fallback_threshold: The number of consecutive retries before falling back to the next GVS server.
+    @param max_empty_requests: The maximum number of consecutive requests with no new segments before giving up.
+    @param live_end_wait_sec: The number of seconds to wait after the last received segment before considering the live stream ended.
+    @param live_end_segment_tolerance: The number of segments before the live head segment at which the livestream is allowed to end. Defaults to 10.
+    @param post_live: Whether the live stream is in post-live mode. Used to determine how to handle the end of the stream.
+    @param video_id: The video ID of the YouTube video. Used for validating received data is for the correct video.
+    @param retry_sleep_func: A function to sleep between retries. If None, will not sleep between retries.
+    @param expiry_threshold_sec: The number of seconds before the GVS expiry to consider it expired. Defaults to 1 minute.
+    """
+
+    # Used for debugging
+    _IGNORED_PARTS = (
+        UMPPartId.REQUEST_IDENTIFIER,
+        UMPPartId.REQUEST_CANCELLATION_POLICY,
+        UMPPartId.PLAYBACK_START_POLICY,
+        UMPPartId.ALLOWED_CACHED_FORMATS,
+        UMPPartId.PAUSE_BW_SAMPLING_HINT,
+        UMPPartId.START_BW_SAMPLING_HINT,
+        UMPPartId.REQUEST_PIPELINING,
+        UMPPartId.SELECTABLE_FORMATS,
+        UMPPartId.PREWARM_CONNECTION,
+    )
+
+    @dataclasses.dataclass
+    class _NoSegmentsTracker:
+        consecutive_requests: int = 0
+        timestamp_started: float | None = None
+        live_head_segment_started: int | None = None
+
+        def reset(self):
+            self.consecutive_requests = 0
+            self.timestamp_started = None
+            self.live_head_segment_started = None
+
+        def increment(self, live_head_segment=None):
+            if self.consecutive_requests == 0:
+                self.timestamp_started = time.time()
+                self.live_head_segment_started = live_head_segment
+            self.consecutive_requests += 1
+
+    def __init__(
+        self,
+        urlopen: typing.Callable[[Request], Response],
+        logger: SabrLogger,
+        server_abr_streaming_url: str,
+        video_playback_ustreamer_config: str,
+        client_info: ClientInfo,
+        audio_selection: AudioSelector | None = None,
+        video_selection: VideoSelector | None = None,
+        caption_selection: CaptionSelector | None = None,
+        live_segment_target_duration_sec: int | None = None,
+        live_segment_target_duration_tolerance_ms: int | None = None,
+        start_time_ms: int | None = None,
+        po_token: str | None = None,
+        http_retries: int | None = None,
+        pot_retries: int | None = None,
+        host_fallback_threshold: int | None = None,
+        max_empty_requests: int | None = None,
+        live_end_wait_sec: int | None = None,
+        live_end_segment_tolerance: int | None = None,
+        post_live: bool = False,
+        video_id: str | None = None,
+        retry_sleep_func: int | None = None,
+        expiry_threshold_sec: int | None = None,
+    ):
+
+        self.logger = logger
+        self._urlopen = urlopen
+
+        self.processor = SabrProcessor(
+            logger=logger,
+            video_playback_ustreamer_config=video_playback_ustreamer_config,
+            client_info=client_info,
+            audio_selection=audio_selection,
+            video_selection=video_selection,
+            caption_selection=caption_selection,
+            live_segment_target_duration_sec=live_segment_target_duration_sec,
+            live_segment_target_duration_tolerance_ms=live_segment_target_duration_tolerance_ms,
+            start_time_ms=start_time_ms,
+            po_token=po_token,
+            live_end_wait_sec=live_end_wait_sec,
+            live_end_segment_tolerance=live_end_segment_tolerance,
+            post_live=post_live,
+            video_id=video_id,
+        )
+        self.url = server_abr_streaming_url
+        self.http_retries = http_retries or 10
+        self.pot_retries = pot_retries or 5
+        self.host_fallback_threshold = host_fallback_threshold or 8
+        self.max_empty_requests = max_empty_requests or 3
+        self.expiry_threshold_sec = expiry_threshold_sec or 60  # 60 seconds
+        if self.expiry_threshold_sec <= 0:
+            raise ValueError('expiry_threshold_sec must be greater than 0')
+        if self.max_empty_requests <= 0:
+            raise ValueError('max_empty_requests must be greater than 0')
+        self.retry_sleep_func = retry_sleep_func
+        self._request_number = 0
+
+        # Whether we got any new (not consumed) segments in the request.
+        self._received_new_segments = False
+        self._no_new_segments_tracker = SabrStream._NoSegmentsTracker()
+        self._sps_retry_manager: typing.Generator | None = None
+        self._current_sps_retry = None
+        self._http_retry_manager: typing.Generator | None = None
+        self._current_http_retry = None
+        self._unknown_part_types = set()
+
+        # Whether the current request is a result of a retry
+        self._is_retry = False
+
+        self._consumed = False
+        self._sq_mismatch_backtrack_count = 0
+        self._sq_mismatch_forward_count = 0
+
+    def close(self):
+        self._consumed = True
+
+    def __iter__(self):
+        return self.iter_parts()
+
+    @property
+    def url(self):
+        return self._url
+
+    @url.setter
+    def url(self, url):
+        self.logger.debug(f'New URL: {url}')
+        if hasattr(self, '_url') and ((bn := broadcast_id_from_url(url)) != (bc := broadcast_id_from_url(self.url))):
+            raise SabrStreamError(f'Broadcast ID changed from {bc} to {bn}. The download will need to be restarted.')
+        self._url = url
+        if str_or_none(parse_qs(url).get('source', [None])[0]) == 'yt_live_broadcast':
+            self.processor.is_live = True
+
+    def iter_parts(self):
+        if self._consumed:
+            raise SabrStreamConsumedError('SABR stream has already been consumed')
+
+        self._http_retry_manager = None
+        self._sps_retry_manager = None
+
+        def report_retry(err, count, retries, fatal=True):
+            if count >= self.host_fallback_threshold:
+                self._process_fallback_server()
+            RetryManager.report_retry(
+                err, count, retries, info=self.logger.info,
+                warn=lambda msg: self.logger.warning(f'[sabr] Got error: {msg}'),
+                error=None if fatal else lambda msg: self.logger.warning(f'[sabr] Got error: {msg}'),
+                sleep_func=self.retry_sleep_func,
+            )
+
+        def report_sps_retry(err, count, retries, fatal=True):
+            RetryManager.report_retry(
+                err, count, retries, info=self.logger.info,
+                warn=lambda msg: self.logger.warning(f'[sabr] Got error: {msg}'),
+                error=None if fatal else lambda msg: self.logger.warning(f'[sabr] Got error: {msg}'),
+                sleep_func=self.retry_sleep_func,
+            )
+
+        while not self._consumed:
+            if self._http_retry_manager is None:
+                self._http_retry_manager = iter(RetryManager(self.http_retries, report_retry))
+
+            if self._sps_retry_manager is None:
+                self._sps_retry_manager = iter(RetryManager(self.pot_retries, report_sps_retry))
+
+            self._current_http_retry = next(self._http_retry_manager)
+            self._current_sps_retry = next(self._sps_retry_manager)
+
+            self._log_state()
+
+            yield from self._process_expiry()
+            vpabr = build_vpabr_request(self.processor)
+            payload = protobug.dumps(vpabr)
+            self.logger.trace(f'Ustreamer Config: {self.processor.video_playback_ustreamer_config}')
+            self.logger.trace(f'Sending SABR request: {vpabr}')
+
+            response = None
+            try:
+                response = self._urlopen(
+                    Request(
+                        url=self.url,
+                        method='POST',
+                        data=payload,
+                        query={'rn': self._request_number},
+                        headers={
+                            'content-type': 'application/x-protobuf',
+                            'accept-encoding': 'identity',
+                            'accept': 'application/vnd.yt-ump',
+                        },
+                    ),
+                )
+                self._request_number += 1
+            except TransportError as e:
+                self._current_http_retry.error = e
+            except HTTPError as e:
+                # retry on 5xx errors only
+                if 500 <= e.status < 600:
+                    self._current_http_retry.error = e
+                else:
+                    raise SabrStreamError(f'HTTP Error: {e.status} - {e.reason}')
+
+            if response:
+                try:
+                    yield from self._parse_ump_response(response)
+                except TransportError as e:
+                    self._current_http_retry.error = e
+
+                if not response.closed:
+                    response.close()
+
+            self._validate_response_integrity()
+            self._process_sps_retry()
+
+            if not self._current_http_retry.error:
+                self._http_retry_manager = None
+
+            if not self._current_sps_retry.error:
+                self._sps_retry_manager = None
+
+            retry_next_request = bool(self._current_http_retry.error or self._current_sps_retry.error)
+
+            # We are expecting to stay in the same place for a retry
+            if not retry_next_request:
+                # Only increment request no segments number if we are not retrying
+                self._process_request_had_segments()
+
+                # Calculate and apply the next playback time to skip to
+                yield from self._prepare_next_playback_time()
+
+                # Request successfully processed, next request is not a retry
+                self._is_retry = False
+            else:
+                self._is_retry = True
+
+            self._received_new_segments = False
+
+        self._consumed = True
+
+    def _process_sps_retry(self):
+        error = PoTokenError(missing=not self.processor.po_token)
+
+        if self.processor.stream_protection_status == StreamProtectionStatus.Status.ATTESTATION_REQUIRED:
+            # Always start retrying immediately on ATTESTATION_REQUIRED
+            self._current_sps_retry.error = error
+            return
+
+        elif (
+            self.processor.stream_protection_status == StreamProtectionStatus.Status.ATTESTATION_PENDING
+            and self._no_new_segments_tracker.consecutive_requests >= self.max_empty_requests
+            and (not self.processor.is_live or self.processor.stream_protection_status or (
+                self.processor.live_metadata is not None
+                and self._no_new_segments_tracker.live_head_segment_started != self.processor.live_metadata.head_sequence_number)
+            )
+        ):
+            # Sometimes YouTube sends no data on ATTESTATION_PENDING, so in this case we need to count retries to fail on a PO Token error.
+            # We only start counting retries after max_empty_requests in case of intermittent no data that we need to increase the player time on.
+            # For livestreams when we receive no new segments, this could be due the stream ending or ATTESTATION_PENDING.
+            # To differentiate the two, we check if the live head segment has changed during the time we start getting no new segments.
+            # xxx: not perfect detection, sometimes get a new segment we can never fetch (partial)
+            self._current_sps_retry.error = error
+            return
+
+    def _process_request_had_segments(self):
+        if not self._received_new_segments:
+            self._no_new_segments_tracker.increment(
+                live_head_segment=self.processor.live_metadata.head_sequence_number if self.processor.live_metadata else None)
+            self.logger.trace(f'No new segments received in request {self._request_number}, count: {self._no_new_segments_tracker.consecutive_requests}')
+        else:
+            self._no_new_segments_tracker.reset()
+
+    def _validate_response_integrity(self):
+        if not len(self.processor.partial_segments):
+            return
+
+        msg = 'Received partial segments: ' + ', '.join(
+            f'{seg.format_id}: {seg.sequence_number}'
+            for seg in self.processor.partial_segments.values()
+        )
+        if self.processor.is_live:
+            # In post live, sometimes we get a partial segment at the end of the stream that should be ignored.
+            # If this occurs mid-stream, other guards should prevent corruption.
+            if (
+                self.processor.live_metadata
+                # TODO: generalize
+                and self.processor.client_abr_state.player_time_ms >= (
+                    self.processor.live_metadata.head_sequence_time_ms - (self.processor.live_segment_target_duration_sec * 1000 * self.processor.live_end_segment_tolerance))
+            ):
+                # Only log a warning if we are not near the head of a stream
+                self.logger.debug(msg)
+            else:
+                self.logger.warning(msg)
+        else:
+            # Should not happen for videos
+            self._current_http_retry.error = SabrStreamError(msg)
+
+        self.processor.partial_segments.clear()
+
+    def _prepare_next_playback_time(self):
+        # TODO: refactor and cleanup this massive function
+        wait_seconds = 0
+        for izf in self.processor.initialized_formats.values():
+            if not izf.current_segment:
+                continue
+
+            # Guard: Check that the segment is not in multiple consumed ranges
+            # This should not happen, but if it does, we should bail
+            count = sum(
+                1 for cr in izf.consumed_ranges
+                if cr.start_sequence_number <= izf.current_segment.sequence_number <= cr.end_sequence_number
+            )
+
+            if count > 1:
+                raise SabrStreamError(f'Segment {izf.current_segment.sequence_number} for format {izf.format_id} in {count} consumed ranges')
+
+            # Check if there is two or more consumed ranges where the end lines up with the start of the other.
+            # This could happen in the case of concurrent playback.
+            # In this case, we should consider a seek as acceptable to the end of the other.
+            # Note: It is assumed a segment is only present in one consumed range - it should not be allowed in multiple (by process media header)
+            prev_consumed_range = next(
+                (cr for cr in izf.consumed_ranges if cr.end_sequence_number == izf.current_segment.sequence_number),
+                None,
+            )
+            # TODO: move to processor MEDIA_END
+            if prev_consumed_range and len(get_cr_chain(prev_consumed_range, izf.consumed_ranges)) >= 2:
+                self.logger.debug(f'Found two or more consumed ranges that line up, allowing a seek for format {izf.format_id}')
+                izf.current_segment = None
+                yield MediaSeekSabrPart(
+                    reason=MediaSeekSabrPart.Reason.CONSUMED_SEEK,
+                    format_id=izf.format_id,
+                    format_selector=izf.format_selector)
+
+        enabled_initialized_formats = [izf for izf in self.processor.initialized_formats.values() if not izf.discard]
+
+        # For each initialized format:
+        #   1. find the consumed format that matches player_time_ms.
+        #   2. find the current consumed range in sequence (in case multiple are joined together)
+        # For livestreams, we allow a tolerance for the segment duration as it is estimated. This tolerance should be less than the segment duration / 2.
+
+        cr_tolerance_ms = 0
+        if self.processor.is_live:
+            cr_tolerance_ms = self.processor.live_segment_target_duration_tolerance_ms
+
+        current_consumed_ranges = []
+        for izf in enabled_initialized_formats:
+            for cr in sorted(izf.consumed_ranges, key=lambda cr: cr.start_sequence_number):
+                if (cr.start_time_ms - cr_tolerance_ms) <= self.processor.client_abr_state.player_time_ms <= cr.start_time_ms + cr.duration_ms + (cr_tolerance_ms * 2):
+                    chain = get_cr_chain(cr, izf.consumed_ranges)
+                    current_consumed_ranges.append(chain[-1])
+                    # There should only be one chain for the current player_time_ms (including the tolerance)
+                    break
+
+        min_consumed_duration_ms = None
+
+        # Get the lowest consumed range end time out of all current consumed ranges.
+        if current_consumed_ranges:
+            lowest_izf_consumed_range = min(current_consumed_ranges, key=lambda cr: cr.start_time_ms + cr.duration_ms)
+            min_consumed_duration_ms = lowest_izf_consumed_range.start_time_ms + lowest_izf_consumed_range.duration_ms
+
+        if len(current_consumed_ranges) != len(enabled_initialized_formats) or min_consumed_duration_ms is None:
+            # Missing a consumed range for a format.
+            # In this case, consider player_time_ms to be our correct next time
+            # May happen in the case of:
+            # 1. A Format has not been initialized yet (can happen if response read fails)
+            # or
+            # 1. SABR_SEEK to time outside both formats consumed ranges
+            # 2. ONE of the formats returns data after the SABR_SEEK in that request
+            if min_consumed_duration_ms is None:
+                min_consumed_duration_ms = self.processor.client_abr_state.player_time_ms
+            else:
+                min_consumed_duration_ms = min(min_consumed_duration_ms, self.processor.client_abr_state.player_time_ms)
+
+        # Usually provided by the server if there was no segments returned.
+        # We'll use this to calculate the time to wait for the next request (for live streams).
+        next_request_backoff_ms = (self.processor.next_request_policy and self.processor.next_request_policy.backoff_time_ms) or 0
+
+        request_player_time = self.processor.client_abr_state.player_time_ms
+        self.logger.trace(f'min consumed duration ms: {min_consumed_duration_ms}')
+        self.processor.client_abr_state.player_time_ms = min_consumed_duration_ms
+
+        # Check if the latest segment is the last one of each format (if data is available)
+        if (
+            not (self.processor.is_live and not self.processor.post_live)
+            and enabled_initialized_formats
+            and len(current_consumed_ranges) == len(enabled_initialized_formats)
+            and all(
+                (
+                    initialized_format.total_segments is not None
+                    # consumed ranges are not guaranteed to be in order
+                    and sorted(
+                        initialized_format.consumed_ranges,
+                        key=lambda cr: cr.end_sequence_number,
+                    )[-1].end_sequence_number >= initialized_format.total_segments
+                )
+                for initialized_format in enabled_initialized_formats
+            )
+        ):
+            self.logger.debug('Reached last expected segment for all enabled formats, assuming end of media')
+            self._consumed = True
+
+        # Check if we have exceeded the total duration of the media (if not live),
+        #  or wait for the next segment (if live)
+        elif self.processor.total_duration_ms and (self.processor.client_abr_state.player_time_ms >= self.processor.total_duration_ms):
+            if self.processor.is_live:
+                self.logger.trace(f'setting player time ms ({self.processor.client_abr_state.player_time_ms}) to total duration ms ({self.processor.total_duration_ms})')
+                self.processor.client_abr_state.player_time_ms = self.processor.total_duration_ms
+                if (
+                    self._no_new_segments_tracker.consecutive_requests > self.max_empty_requests
+                    and not self._is_retry
+                    and self._no_new_segments_tracker.timestamp_started < time.time() + self.processor.live_end_wait_sec
+                ):
+                    self.logger.debug(f'No new segments received for at least {self.processor.live_end_wait_sec} seconds, assuming end of live stream')
+                    self._consumed = True
+                else:
+                    wait_seconds = max(next_request_backoff_ms / 1000, self.processor.live_segment_target_duration_sec)
+            else:
+                self.logger.debug(f'End of media (player time ms {self.processor.client_abr_state.player_time_ms} >= total duration ms {self.processor.total_duration_ms})')
+                self._consumed = True
+
+        # Handle receiving no new segments before end the end of the video/stream
+        # For videos, if exceeds max_empty_requests, this should not happen so we raise an error
+        # For livestreams, if we exceed max_empty_requests, and we don't have live_metadata,
+        #   and have not received any data for a while, we can assume the stream has ended (as we don't know the head sequence number)
+        elif (
+            # Determine if we are receiving no segments as the live stream has ended.
+            # Allow some tolerance the head segment may not be able to be received.
+            self.processor.is_live and not self.processor.post_live
+            and (
+                getattr(self.processor.live_metadata, 'head_sequence_number', None) is None
+                or (
+                    enabled_initialized_formats
+                    and len(current_consumed_ranges) == len(enabled_initialized_formats)
+                    and all(
+                        (
+                            initialized_format.total_segments is not None
+                            and sorted(
+                                initialized_format.consumed_ranges,
+                                key=lambda cr: cr.end_sequence_number,
+                            )[-1].end_sequence_number
+                            >= initialized_format.total_segments - self.processor.live_end_segment_tolerance
+                        )
+                        for initialized_format in enabled_initialized_formats
+                    )
+                )
+                or self.processor.live_metadata.head_sequence_time_ms is None
+                or (
+                    # Sometimes we receive a partial segment at the end of the stream
+                    # and the server seeks us to the end of the current segment.
+                    # As our consumed range for this segment has an estimated end time,
+                    # this may be slightly off what the server seeks to.
+                    # This can cause the player time to be slightly outside the consumed range.
+                    #
+                    # Because of this, we should also check the player time against
+                    # the head segment time using the estimated segment duration.
+                    # xxx: consider also taking into account the max seekable timestamp
+                    request_player_time >= self.processor.live_metadata.head_sequence_time_ms - (self.processor.live_segment_target_duration_sec * 1000 * self.processor.live_end_segment_tolerance)
+                )
+            )
+        ):
+            if (
+                not self._is_retry  # allow us to sleep on a retry
+                and self._no_new_segments_tracker.consecutive_requests > self.max_empty_requests
+                and self._no_new_segments_tracker.timestamp_started < time.time() + self.processor.live_end_wait_sec
+            ):
+                self.logger.debug(f'No new segments received for at least {self.processor.live_end_wait_sec} seconds; assuming end of live stream')
+                self._consumed = True
+            elif self._no_new_segments_tracker.consecutive_requests >= 1:
+                # Sometimes we can't get the head segment - rather tend to sit behind the head segment for the duration of the livestream
+                wait_seconds = max(next_request_backoff_ms / 1000, self.processor.live_segment_target_duration_sec)
+        elif (
+            self._no_new_segments_tracker.consecutive_requests > self.max_empty_requests
+            and not self._is_retry
+        ):
+            raise SabrStreamError('No new segments received in three consecutive requests')
+
+        elif (
+            not self.processor.is_live and next_request_backoff_ms
+            and self._no_new_segments_tracker.consecutive_requests >= 1
+            and any(t in self.processor.sabr_contexts_to_send for t in self.processor.sabr_context_updates)
+        ):
+            wait_seconds = math.ceil(next_request_backoff_ms / 1000)
+            self.logger.info(f'The server is requiring yt-dlp to wait {wait_seconds} seconds before continuing due to ad enforcement')
+
+        if wait_seconds:
+            self.logger.debug(f'Waiting {wait_seconds} seconds for next segment(s)')
+            time.sleep(wait_seconds)
+
+    def _parse_ump_response(self, response):
+        self._unknown_part_types.clear()
+        ump = UMPDecoder(response)
+        for part in ump.iter_parts():
+            if part.part_id == UMPPartId.MEDIA_HEADER:
+                yield from self._process_media_header(part)
+            elif part.part_id == UMPPartId.MEDIA:
+                yield from self._process_media(part)
+            elif part.part_id == UMPPartId.MEDIA_END:
+                yield from self._process_media_end(part)
+            elif part.part_id == UMPPartId.STREAM_PROTECTION_STATUS:
+                yield from self._process_stream_protection_status(part)
+            elif part.part_id == UMPPartId.SABR_REDIRECT:
+                self._process_sabr_redirect(part)
+            elif part.part_id == UMPPartId.FORMAT_INITIALIZATION_METADATA:
+                yield from self._process_format_initialization_metadata(part)
+            elif part.part_id == UMPPartId.NEXT_REQUEST_POLICY:
+                self._process_next_request_policy(part)
+            elif part.part_id == UMPPartId.LIVE_METADATA:
+                yield from self._process_live_metadata(part)
+            elif part.part_id == UMPPartId.SABR_SEEK:
+                yield from self._process_sabr_seek(part)
+            elif part.part_id == UMPPartId.SABR_ERROR:
+                self._process_sabr_error(part)
+            elif part.part_id == UMPPartId.SABR_CONTEXT_UPDATE:
+                self._process_sabr_context_update(part)
+            elif part.part_id == UMPPartId.SABR_CONTEXT_SENDING_POLICY:
+                self._process_sabr_context_sending_policy(part)
+            elif part.part_id == UMPPartId.RELOAD_PLAYER_RESPONSE:
+                yield from self._process_reload_player_response(part)
+            else:
+                if part.part_id not in self._IGNORED_PARTS:
+                    self._unknown_part_types.add(part.part_id)
+                self._log_part(part, msg='Unhandled part type', data=part.data.read())
+
+            # Cancel request processing if we are going to retry
+            if self._current_sps_retry.error or self._current_http_retry.error:
+                self.logger.debug('Request processing cancelled')
+                return
+
+    def _process_media_header(self, part: UMPPart):
+        media_header = protobug.load(part.data, MediaHeader)
+        self._log_part(part=part, protobug_obj=media_header)
+
+        try:
+            result = self.processor.process_media_header(media_header)
+            if result.sabr_part:
+                yield result.sabr_part
+        except MediaSegmentMismatchError as e:
+            # For livestreams, the server may not know the exact segment for a given player time.
+            # For segments near stream head, it estimates using segment duration, which can cause off-by-one segment mismatches.
+            # If a segment is much longer or shorter than expected, the server may return a segment ahead or behind.
+            # In such cases, retry with an adjusted player time to resync.
+            if self.processor.is_live and e.received_sequence_number == e.expected_sequence_number - 1:
+                # The segment before the previous segment was possibly longer than expected.
+                # Move the player time forward to try to adjust for this.
+                self.processor.client_abr_state.player_time_ms += self.processor.live_segment_target_duration_tolerance_ms
+                self._sq_mismatch_forward_count += 1
+                self._current_http_retry.error = e
+                return
+            elif self.processor.is_live and e.received_sequence_number == e.expected_sequence_number + 2:
+                # The previous segment was possibly shorter than expected
+                # Move the player time backwards to try to adjust for this.
+                self.processor.client_abr_state.player_time_ms = max(0, self.processor.client_abr_state.player_time_ms - self.processor.live_segment_target_duration_tolerance_ms)
+                self._sq_mismatch_backtrack_count += 1
+                self._current_http_retry.error = e
+                return
+            raise e
+
+    def _process_media(self, part: UMPPart):
+        header_id = read_varint(part.data)
+        content_length = part.size - part.data.tell()
+        result = self.processor.process_media(header_id, content_length, part.data)
+        if result.sabr_part:
+            yield result.sabr_part
+
+    def _process_media_end(self, part: UMPPart):
+        header_id = read_varint(part.data)
+        self._log_part(part, msg=f'Header ID: {header_id}')
+
+        result = self.processor.process_media_end(header_id)
+        if result.is_new_segment:
+            self._received_new_segments = True
+
+        if result.sabr_part:
+            yield result.sabr_part
+
+    def _process_live_metadata(self, part: UMPPart):
+        live_metadata = protobug.load(part.data, LiveMetadata)
+        self._log_part(part, protobug_obj=live_metadata)
+        yield from self.processor.process_live_metadata(live_metadata).seek_sabr_parts
+
+    def _process_stream_protection_status(self, part: UMPPart):
+        sps = protobug.load(part.data, StreamProtectionStatus)
+        self._log_part(part, msg=f'Status: {StreamProtectionStatus.Status(sps.status).name}', protobug_obj=sps)
+        result = self.processor.process_stream_protection_status(sps)
+        if result.sabr_part:
+            yield result.sabr_part
+
+    def _process_sabr_redirect(self, part: UMPPart):
+        sabr_redirect = protobug.load(part.data, SabrRedirect)
+        self._log_part(part, protobug_obj=sabr_redirect)
+        if not sabr_redirect.redirect_url:
+            self.logger.warning('Server requested to redirect to an invalid URL')
+            return
+        self.url = sabr_redirect.redirect_url
+
+    def _process_format_initialization_metadata(self, part: UMPPart):
+        fmt_init_metadata = protobug.load(part.data, FormatInitializationMetadata)
+        self._log_part(part, protobug_obj=fmt_init_metadata)
+        result = self.processor.process_format_initialization_metadata(fmt_init_metadata)
+        if result.sabr_part:
+            yield result.sabr_part
+
+    def _process_next_request_policy(self, part: UMPPart):
+        next_request_policy = protobug.load(part.data, NextRequestPolicy)
+        self._log_part(part, protobug_obj=next_request_policy)
+        self.processor.process_next_request_policy(next_request_policy)
+
+    def _process_sabr_seek(self, part: UMPPart):
+        sabr_seek = protobug.load(part.data, SabrSeek)
+        self._log_part(part, protobug_obj=sabr_seek)
+        yield from self.processor.process_sabr_seek(sabr_seek).seek_sabr_parts
+
+    def _process_sabr_error(self, part: UMPPart):
+        sabr_error = protobug.load(part.data, SabrError)
+        self._log_part(part, protobug_obj=sabr_error)
+        self._current_http_retry.error = SabrStreamError(f'SABR Protocol Error: {sabr_error}')
+
+    def _process_sabr_context_update(self, part: UMPPart):
+        sabr_ctx_update = protobug.load(part.data, SabrContextUpdate)
+        self._log_part(part, protobug_obj=sabr_ctx_update)
+        self.processor.process_sabr_context_update(sabr_ctx_update)
+
+    def _process_sabr_context_sending_policy(self, part: UMPPart):
+        sabr_ctx_sending_policy = protobug.load(part.data, SabrContextSendingPolicy)
+        self._log_part(part, protobug_obj=sabr_ctx_sending_policy)
+        self.processor.process_sabr_context_sending_policy(sabr_ctx_sending_policy)
+
+    def _process_reload_player_response(self, part: UMPPart):
+        reload_player_response = protobug.load(part.data, ReloadPlayerResponse)
+        self._log_part(part, protobug_obj=reload_player_response)
+        yield RefreshPlayerResponseSabrPart(
+            reason=RefreshPlayerResponseSabrPart.Reason.SABR_RELOAD_PLAYER_RESPONSE,
+            reload_playback_token=reload_player_response.reload_playback_params.token,
+        )
+
+    def _process_fallback_server(self):
+        # Attempt to fall back to another GVS host in the case the current one fails
+        new_url = next_gvs_fallback_url(self.url)
+        if not new_url:
+            self.logger.debug('No more fallback hosts available')
+
+        self.logger.warning(f'Falling back to host {urllib.parse.urlparse(new_url).netloc}')
+        self.url = new_url
+
+    def _gvs_expiry(self):
+        return int_or_none(traverse_obj(parse_qs(self.url), ('expire', 0), get_all=False))
+
+    def _process_expiry(self):
+        expires_at = self._gvs_expiry()
+
+        if not expires_at:
+            self.logger.warning(
+                'No expiry timestamp found in SABR URL. Will not be able to refresh.', once=True)
+            return
+
+        if expires_at - self.expiry_threshold_sec >= time.time():
+            self.logger.trace(f'SABR url expires in {int(expires_at - time.time())} seconds')
+            return
+
+        self.logger.debug(
+            f'Requesting player response refresh as SABR URL is due to expire in {self.expiry_threshold_sec} seconds')
+        yield RefreshPlayerResponseSabrPart(reason=RefreshPlayerResponseSabrPart.Reason.SABR_URL_EXPIRY)
+
+    def _log_part(self, part: UMPPart, msg=None, protobug_obj=None, data=None):
+        if self.logger.log_level > self.logger.LogLevel.TRACE:
+            return
+        message = f'[{part.part_id.name}]: (Size {part.size})'
+        if protobug_obj:
+            message += f' Parsed: {protobug_obj}'
+            uf = list(unknown_fields(protobug_obj))
+            if uf:
+                message += f' (Unknown fields: {uf})'
+        if msg:
+            message += f' {msg}'
+        if data:
+            message += f' Data: {base64.b64encode(data).decode("utf-8")}'
+        self.logger.trace(message.strip())
+
+    def _log_state(self):
+        # TODO: refactor
+        if self.logger.log_level > self.logger.LogLevel.DEBUG:
+            return
+
+        if self.processor.is_live and self.processor.post_live:
+            live_message = f'post_live ({self.processor.live_segment_target_duration_sec}s)'
+        elif self.processor.is_live:
+            live_message = f'live ({self.processor.live_segment_target_duration_sec}s)'
+        else:
+            live_message = 'not_live'
+
+        if self.processor.is_live:
+            live_message += ' bid:' + str_or_none(broadcast_id_from_url(self.url))
+
+        consumed_ranges_message = (
+            ', '.join(
+                f'{izf.format_id.itag}:'
+                + ', '.join(
+                    f'{cf.start_sequence_number}-{cf.end_sequence_number} '
+                    f'({cf.start_time_ms}-'
+                    f'{cf.start_time_ms + cf.duration_ms})'
+                    for cf in izf.consumed_ranges
+                )
+                for izf in self.processor.initialized_formats.values()
+            ) or 'none'
+        )
+
+        izf_parts = []
+        for izf in self.processor.initialized_formats.values():
+            s = f'{izf.format_id.itag}'
+            if izf.discard:
+                s += 'd'
+            p = []
+            if izf.total_segments:
+                p.append(f'{izf.total_segments}')
+            if izf.sequence_lmt is not None:
+                p.append(f'lmt={izf.sequence_lmt}')
+            if p:
+                s += ('(' + ','.join(p) + ')')
+            izf_parts.append(s)
+
+        initialized_formats_message = ', '.join(izf_parts) or 'none'
+
+        unknown_part_message = ''
+        if self._unknown_part_types:
+            unknown_part_message = 'unkpt:' + ', '.join(part_type.name for part_type in self._unknown_part_types)
+
+        sabr_context_update_msg = ''
+        if self.processor.sabr_context_updates:
+            sabr_context_update_msg += 'cu:[' + ','.join(
+                f'{k}{"(n)" if k not in self.processor.sabr_contexts_to_send else ""}'
+                for k in self.processor.sabr_context_updates
+            ) + ']'
+
+        self.logger.debug(
+            "[SABR State] "
+            f"v:{self.processor.video_id or 'unknown'} "
+            f"c:{self.processor.client_info.client_name.name} "
+            f"t:{self.processor.client_abr_state.player_time_ms} "
+            f"td:{self.processor.total_duration_ms if self.processor.total_duration_ms else 'n/a'} "
+            f"h:{urllib.parse.urlparse(self.url).netloc} "
+            f"exp:{dt.timedelta(seconds=int(self._gvs_expiry() - time.time())) if self._gvs_expiry() else 'n/a'} "
+            f"rn:{self._request_number} rnns:{self._no_new_segments_tracker.consecutive_requests} "
+            f"lnns:{self._no_new_segments_tracker.live_head_segment_started or 'n/a'} "
+            f"mmb:{self._sq_mismatch_backtrack_count} mmf:{self._sq_mismatch_forward_count} "
+            f"pot:{'Y' if self.processor.po_token else 'N'} "
+            f"sps:{self.processor.stream_protection_status.name if self.processor.stream_protection_status else 'n/a'} "
+            f"{live_message} "
+            f"if:[{initialized_formats_message}] "
+            f"cr:[{consumed_ranges_message}] "
+            f"{sabr_context_update_msg} "
+            f"{unknown_part_message}",
+        )
--- a/yt_dlp/extractor/youtube/_streaming/sabr/utils.py
+++ b/yt_dlp/extractor/youtube/_streaming/sabr/utils.py
@ -0,0 +1,83 @@
+from __future__ import annotations
+
+import contextlib
+import math
+import urllib.parse
+
+from yt_dlp.extractor.youtube._streaming.sabr.models import ConsumedRange
+from yt_dlp.utils import int_or_none, orderedSet, parse_qs, str_or_none, update_url_query
+
+
+def get_cr_chain(start_consumed_range: ConsumedRange, consumed_ranges: list[ConsumedRange]) -> list[ConsumedRange]:
+    # TODO: unit test
+    # Return the continuous consumed range chain starting from the given consumed range
+    # Note: It is assumed a segment is only present in one consumed range - it should not be allowed in multiple (by process media header)
+    chain = [start_consumed_range]
+    for cr in sorted(consumed_ranges, key=lambda r: r.start_sequence_number):
+        if cr.start_sequence_number == chain[-1].end_sequence_number + 1:
+            chain.append(cr)
+        elif cr.start_sequence_number > chain[-1].end_sequence_number + 1:
+            break
+    return chain
+
+
+def next_gvs_fallback_url(gvs_url):
+    # TODO: unit test
+    qs = parse_qs(gvs_url)
+    gvs_url_parsed = urllib.parse.urlparse(gvs_url)
+    fvip = int_or_none(qs.get('fvip', [None])[0])
+    mvi = int_or_none(qs.get('mvi', [None])[0])
+    mn = str_or_none(qs.get('mn', [None])[0], default='').split(',')
+    fallback_count = int_or_none(qs.get('fallback_count', ['0'])[0], default=0)
+
+    hosts = []
+
+    def build_host(current_host, f, m):
+        rr = current_host.startswith('rr')
+        if f is None or m is None:
+            return None
+        return ('rr' if rr else 'r') + str(f) + '---' + m + '.googlevideo.com'
+
+    original_host = build_host(gvs_url_parsed.netloc, mvi, mn[0])
+
+    # Order of fallback hosts:
+    # 1. Fallback host in url (mn[1] + fvip)
+    # 2. Fallback hosts brute forced (this usually contains the original host)
+    for mn_entry in reversed(mn):
+        for fvip_entry in orderedSet([fvip, 1, 2, 3, 4, 5]):
+            fallback_host = build_host(gvs_url_parsed.netloc, fvip_entry, mn_entry)
+            if fallback_host and fallback_host not in hosts:
+                hosts.append(fallback_host)
+
+    if not hosts or len(hosts) == 1:
+        return None
+
+    # if first fallback, anchor to start of list so we start with the known fallback hosts
+    # Sometimes we may get a SABR_REDIRECT after a fallback, which gives a new host with new fallbacks.
+    # In this case, the original host indicated by the url params would match the current host
+    current_host_index = -1
+    if fallback_count > 0 and gvs_url_parsed.netloc != original_host:
+        with contextlib.suppress(ValueError):
+            current_host_index = hosts.index(gvs_url_parsed.netloc)
+
+    def next_host(idx, h):
+        return h[(idx + 1) % len(h)]
+
+    new_host = next_host(current_host_index + 1, hosts)
+    # If the current URL only has one fallback host, then the first fallback host is the same as the current host.
+    if new_host == gvs_url_parsed.netloc:
+        new_host = next_host(current_host_index + 2, hosts)
+
+    # TODO: do not return new_host if it still matches the original host
+    return update_url_query(
+        gvs_url_parsed._replace(netloc=new_host).geturl(), {'fallback_count': fallback_count + 1})
+
+
+def ticks_to_ms(time_ticks: int, timescale: int):
+    if time_ticks is None or timescale is None:
+        return None
+    return math.ceil((time_ticks / timescale) * 1000)
+
+
+def broadcast_id_from_url(url: str) -> str | None:
+    return str_or_none(parse_qs(url).get('id', [None])[0])
--- a/yt_dlp/extractor/youtube/_streaming/ump.py
+++ b/yt_dlp/extractor/youtube/_streaming/ump.py
@ -0,0 +1,116 @@
+import dataclasses
+import enum
+import io
+
+
+class UMPPartId(enum.IntEnum):
+    UNKNOWN = -1
+    ONESIE_HEADER = 10
+    ONESIE_DATA = 11
+    ONESIE_ENCRYPTED_MEDIA = 12
+    MEDIA_HEADER = 20
+    MEDIA = 21
+    MEDIA_END = 22
+    LIVE_METADATA = 31
+    HOSTNAME_CHANGE_HINT = 32
+    LIVE_METADATA_PROMISE = 33
+    LIVE_METADATA_PROMISE_CANCELLATION = 34
+    NEXT_REQUEST_POLICY = 35
+    USTREAMER_VIDEO_AND_FORMAT_DATA = 36
+    FORMAT_SELECTION_CONFIG = 37
+    USTREAMER_SELECTED_MEDIA_STREAM = 38
+    FORMAT_INITIALIZATION_METADATA = 42
+    SABR_REDIRECT = 43
+    SABR_ERROR = 44
+    SABR_SEEK = 45
+    RELOAD_PLAYER_RESPONSE = 46
+    PLAYBACK_START_POLICY = 47
+    ALLOWED_CACHED_FORMATS = 48
+    START_BW_SAMPLING_HINT = 49
+    PAUSE_BW_SAMPLING_HINT = 50
+    SELECTABLE_FORMATS = 51
+    REQUEST_IDENTIFIER = 52
+    REQUEST_CANCELLATION_POLICY = 53
+    ONESIE_PREFETCH_REJECTION = 54
+    TIMELINE_CONTEXT = 55
+    REQUEST_PIPELINING = 56
+    SABR_CONTEXT_UPDATE = 57
+    STREAM_PROTECTION_STATUS = 58
+    SABR_CONTEXT_SENDING_POLICY = 59
+    LAWNMOWER_POLICY = 60
+    SABR_ACK = 61
+    END_OF_TRACK = 62
+    CACHE_LOAD_POLICY = 63
+    LAWNMOWER_MESSAGING_POLICY = 64
+    PREWARM_CONNECTION = 65
+    PLAYBACK_DEBUG_INFO = 66
+    SNACKBAR_MESSAGE = 67
+
+    @classmethod
+    def _missing_(cls, value):
+        return cls.UNKNOWN
+
+
+@dataclasses.dataclass
+class UMPPart:
+    part_id: UMPPartId
+    size: int
+    data: io.BufferedIOBase
+
+
+class UMPDecoder:
+    def __init__(self, fp: io.BufferedIOBase):
+        self.fp = fp
+
+    def iter_parts(self):
+        while not self.fp.closed:
+            part_type = read_varint(self.fp)
+            if part_type == -1 and not self.fp.closed:
+                self.fp.close()
+
+            if self.fp.closed:
+                break
+            part_size = read_varint(self.fp)
+            if part_size == -1 and not self.fp.closed:
+                self.fp.close()
+
+            if self.fp.closed:
+                raise EOFError('Unexpected EOF while reading part size')
+
+            part_data = self.fp.read(part_size)
+            # In the future, we could allow streaming the part data.
+            # But we will need to ensure that each part is completely read before continuing.
+            yield UMPPart(UMPPartId(part_type), part_size, io.BytesIO(part_data))
+
+
+def read_varint(fp: io.BufferedIOBase) -> int:
+    # https://web.archive.org/web/20250430054327/https://github.com/gsuberland/UMP_Format/blob/main/UMP_Format.md
+    # https://web.archive.org/web/20250429151021/https://github.com/davidzeng0/innertube/blob/main/googlevideo/ump.md
+    byte = fp.read(1)
+    if not byte:
+        # Expected EOF
+        return -1
+
+    prefix = byte[0]
+    size = varint_size(prefix)
+    result = 0
+    shift = 0
+
+    if size != 5:
+        shift = 8 - size
+        mask = (1 << shift) - 1
+        result |= prefix & mask
+
+    for _ in range(1, size):
+        next_byte = fp.read(1)
+        if not next_byte:
+            return -1
+        byte_int = next_byte[0]
+        result |= byte_int << shift
+        shift += 8
+
+    return result
+
+
+def varint_size(byte: int) -> int:
+    return 1 if byte < 128 else 2 if byte < 192 else 3 if byte < 224 else 4 if byte < 240 else 5
--- a/yt_dlp/extractor/youtube/_video.py
+++ b/yt_dlp/extractor/youtube/_video.py
@ -26,6 +26,7 @@
 from .pot._director import initialize_pot_director
 from .pot.provider import PoTokenContext, PoTokenRequest
 from ..openload import PhantomJSwrapper
+from ...dependencies import protobug
 from ...jsinterp import JSInterpreter
 from ...networking.exceptions import HTTPError
 from ...utils import (
@ -72,6 +73,7 @@

 STREAMING_DATA_CLIENT_NAME = '__yt_dlp_client'
 STREAMING_DATA_INITIAL_PO_TOKEN = '__yt_dlp_po_token'
+STREAMING_DATA_FETCH_PO_TOKEN = '__yt_dlp_fetch_po_token'
 STREAMING_DATA_FETCH_SUBS_PO_TOKEN = '__yt_dlp_fetch_subs_po_token'
 STREAMING_DATA_INNERTUBE_CONTEXT = '__yt_dlp_innertube_context'

@ -1824,7 +1826,8 @@ def _real_initialize(self):
    def _prepare_live_from_start_formats(self, formats, video_id, live_start_time, url, webpage_url, smuggled_data, is_live):
        lock = threading.Lock()
        start_time = time.time()
-        formats = [f for f in formats if f.get('is_from_start')]
+        # TODO: only include dash formats
+        formats = [f for f in formats if f.get('is_from_start') and f.get('protocol') != 'sabr']

        def refetch_manifest(format_id, delay):
            nonlocal formats, start_time, is_live
@ -1836,7 +1839,7 @@ def refetch_manifest(format_id, delay):
            microformats = traverse_obj(
                prs, (..., 'microformat', 'playerMicroformatRenderer'),
                expected_type=dict)
-            _, live_status, _, formats, _ = self._list_formats(video_id, microformats, video_details, prs, player_url)
+            _, live_status, formats, _ = self._list_formats(video_id, microformats, video_details, prs, player_url)
            is_live = live_status == 'is_live'
            start_time = time.time()

@ -2812,16 +2815,25 @@ def _get_checkok_params():
        return {'contentCheckOk': True, 'racyCheckOk': True}

    @classmethod
-    def _generate_player_context(cls, sts=None):
-        context = {
+    def _generate_player_context(cls, sts=None, reload_playback_token=None):
+        content_playback_context = {
            'html5Preference': 'HTML5_PREF_WANTS',
+            'isInlinePlaybackNoAd': True,
        }
        if sts is not None:
-            context['signatureTimestamp'] = sts
+            content_playback_context['signatureTimestamp'] = sts
+
+        playback_context = {
+            'contentPlaybackContext': content_playback_context,
+        }
+
+        if reload_playback_token:
+            playback_context['reloadPlaybackContext'] = {
+                'reloadPlaybackParams': {'token': reload_playback_token},
+            }
+
        return {
-            'playbackContext': {
-                'contentPlaybackContext': context,
-            },
+            'playbackContext': playback_context,
            **cls._get_checkok_params(),
        }

@ -2863,7 +2875,7 @@ def _get_config_po_token(self, client: str, context: _PoTokenContext):

    def fetch_po_token(self, client='web', context=_PoTokenContext.GVS, ytcfg=None, visitor_data=None,
                       data_sync_id=None, session_index=None, player_url=None, video_id=None, webpage=None,
-                       required=False, **kwargs):
+                       required=False, bypass_cache=None, **kwargs):
        """
        Fetch a PO Token for a given client and context. This function will validate required parameters for a given context and client.

@ -2879,6 +2891,7 @@ def fetch_po_token(self, client='web', context=_PoTokenContext.GVS, ytcfg=None,
        @param video_id: video ID.
        @param webpage: video webpage.
        @param required: Whether the PO Token is required (i.e. try to fetch unless policy is "never").
+        @param bypass_cache: Whether to bypass the cache.
        @param kwargs: Additional arguments to pass down. May be more added in the future.
        @return: The fetched PO Token. None if it could not be fetched.
        """
@ -2900,7 +2913,7 @@ def fetch_po_token(self, client='web', context=_PoTokenContext.GVS, ytcfg=None,
            return

        config_po_token = self._get_config_po_token(client, context)
-        if config_po_token:
+        if config_po_token and not bypass_cache:
            # GVS WebPO token is bound to data_sync_id / account Session ID when logged in.
            if player_url and context == _PoTokenContext.GVS and not data_sync_id and self.is_authenticated:
                self.report_warning(
@ -2927,6 +2940,7 @@ def fetch_po_token(self, client='web', context=_PoTokenContext.GVS, ytcfg=None,
            player_url=player_url,
            video_id=video_id,
            video_webpage=webpage,
+            bypass_cache=bypass_cache,
            required=required,
            **kwargs,
        )
@ -2984,7 +2998,7 @@ def _fetch_po_token(self, client, **kwargs):
            request_verify_tls=not self.get_param('nocheckcertificate'),
            request_source_address=self.get_param('source_address'),

-            bypass_cache=False,
+            bypass_cache=kwargs.get('bypass_cache', False),
        )

        return self._pot_director.get_po_token(pot_request)
@ -3005,7 +3019,7 @@ def _is_agegated(player_response):
    def _is_unplayable(player_response):
        return traverse_obj(player_response, ('playabilityStatus', 'status')) == 'UNPLAYABLE'

-    def _extract_player_response(self, client, video_id, master_ytcfg, player_ytcfg, player_url, initial_pr, visitor_data, data_sync_id, po_token):
+    def _extract_player_response(self, client, video_id, master_ytcfg, player_ytcfg, player_url, initial_pr, visitor_data, data_sync_id, po_token, reload_playback_token):
        headers = self.generate_api_headers(
            ytcfg=player_ytcfg,
            default_client=client,
@ -3034,7 +3048,8 @@ def _extract_player_response(self, client, video_id, master_ytcfg, player_ytcfg,
            yt_query['serviceIntegrityDimensions'] = {'poToken': po_token}

        sts = self._extract_signature_timestamp(video_id, player_url, master_ytcfg, fatal=False) if player_url else None
-        yt_query.update(self._generate_player_context(sts))
+        yt_query.update(self._generate_player_context(sts, reload_playback_token))
+
        return self._extract_response(
            item_id=video_id, ep='player', query=yt_query,
            ytcfg=player_ytcfg, headers=headers, fatal=True,
@ -3087,7 +3102,7 @@ def _invalid_player_response(self, pr, video_id):
        if (pr_id := traverse_obj(pr, ('videoDetails', 'videoId'))) != video_id:
            return pr_id

-    def _extract_player_responses(self, clients, video_id, webpage, master_ytcfg, smuggled_data):
+    def _extract_player_responses(self, clients, video_id, webpage, master_ytcfg, reload_playback_token):
        initial_pr = None
        if webpage:
            initial_pr = self._search_json(
@ -3136,7 +3151,7 @@ def append_client(*client_names):
                player_url = self._download_player_url(video_id)
                tried_iframe_fallback = True

-            pr = initial_pr if client == 'web' else None
+            pr = initial_pr if client == 'web' and not reload_playback_token else None

            visitor_data = visitor_data or self._extract_visitor_data(master_ytcfg, initial_pr, player_ytcfg)
            data_sync_id = data_sync_id or self._extract_data_sync_id(master_ytcfg, initial_pr, player_ytcfg)
@ -3156,8 +3171,13 @@ def append_client(*client_names):
            player_po_token = None if pr else self.fetch_po_token(
                context=_PoTokenContext.PLAYER, **fetch_po_token_args)

-            gvs_po_token = self.fetch_po_token(
-                context=_PoTokenContext.GVS, **fetch_po_token_args)
+            fetch_gvs_po_token_func = functools.partial(
+                self.fetch_po_token,
+                context=_PoTokenContext.GVS,
+                **fetch_po_token_args,
+            )
+
+            gvs_po_token = fetch_gvs_po_token_func()

            fetch_subs_po_token_func = functools.partial(
                self.fetch_po_token,
@ -3200,7 +3220,8 @@ def append_client(*client_names):
                    initial_pr=initial_pr,
                    visitor_data=visitor_data,
                    data_sync_id=data_sync_id,
-                    po_token=player_po_token)
+                    po_token=player_po_token,
+                    reload_playback_token=reload_playback_token)
            except ExtractorError as e:
                self.report_warning(e)
                continue
@ -3215,9 +3236,12 @@ def append_client(*client_names):
                sd[STREAMING_DATA_INITIAL_PO_TOKEN] = gvs_po_token
                sd[STREAMING_DATA_INNERTUBE_CONTEXT] = innertube_context
                sd[STREAMING_DATA_FETCH_SUBS_PO_TOKEN] = fetch_subs_po_token_func
+                sd[STREAMING_DATA_FETCH_PO_TOKEN] = fetch_gvs_po_token_func
                for f in traverse_obj(sd, (('formats', 'adaptiveFormats'), ..., {dict})):
                    f[STREAMING_DATA_CLIENT_NAME] = client
                    f[STREAMING_DATA_INITIAL_PO_TOKEN] = gvs_po_token
+                    f[STREAMING_DATA_INNERTUBE_CONTEXT] = innertube_context
+                    f[STREAMING_DATA_FETCH_PO_TOKEN] = fetch_gvs_po_token_func
                if deprioritize_pr:
                    deprioritized_prs.append(pr)
                else:
@ -3295,12 +3319,54 @@ def _report_pot_subtitles_skipped(self, video_id, client_name, msg=None):
        else:
            self.report_warning(msg, only_once=True)

-    def _extract_formats_and_subtitles(self, streaming_data, video_id, player_url, live_status, duration):
+    def _process_n_param(self, gvs_url, video_id, player_url, proto='https'):
+        query = parse_qs(gvs_url)
+        if query.get('n'):
+            try:
+                decrypt_nsig = self._cached(self._decrypt_nsig, 'nsig', query['n'][0])
+                return update_url_query(gvs_url, {
+                    'n': decrypt_nsig(query['n'][0], video_id, player_url),
+                })
+            except ExtractorError as e:
+                if player_url:
+                    self.report_warning(
+                        f'nsig extraction failed: Some {proto} formats may be missing\n'
+                        f'         n = {query["n"][0]} ; player = {player_url}\n'
+                        f'         {bug_reports_message(before="")}',
+                        video_id=video_id, only_once=True)
+                    self.write_debug(e, only_once=True)
+                else:
+                    self.report_warning(
+                        f'Cannot decrypt nsig without player_url: Some {proto} formats may be missing',
+                        video_id=video_id, only_once=True)
+                return None
+        return gvs_url
+
+    def _reload_sabr_config(self, video_id, client_name, reload_playback_token):
+        # xxx: may also update client info?
+        url = 'https://www.youtube.com/watch?v=' + video_id
+        _, _, prs, player_url = self._download_player_responses(url, {}, video_id, url, reload_playback_token)
+        video_details = traverse_obj(prs, (..., 'videoDetails'), expected_type=dict)
+        microformats = traverse_obj(
+            prs, (..., 'microformat', 'playerMicroformatRenderer'),
+            expected_type=dict)
+        _, live_status, formats, _ = self._list_formats(video_id, microformats, video_details, prs, player_url)
+
+        for f in formats:
+            if f.get('protocol') == 'sabr':
+                sabr_config = f['_sabr_config']
+                if sabr_config['client_name'] == client_name:
+                    return f['url'], sabr_config['video_playback_ustreamer_config']
+
+        raise ExtractorError('No SABR formats found', expected=True)
+
+    def _extract_formats_and_subtitles(self, video_id, player_responses, player_url, live_status, duration):
        CHUNK_SIZE = 10 << 20
        PREFERRED_LANG_VALUE = 10
        original_language = None
        itags, stream_ids = collections.defaultdict(set), []
        itag_qualities, res_qualities = {}, {0: None}
+        subtitles = {}
        q = qualities([
            # Normally tiny is the smallest video-only formats. But
            # audio-only formats with unknown quality may get tagged as tiny
@ -3308,7 +3374,6 @@ def _extract_formats_and_subtitles(self, streaming_data, video_id, player_url, l
            'audio_quality_ultralow', 'audio_quality_low', 'audio_quality_medium', 'audio_quality_high',  # Audio only formats
            'small', 'medium', 'large', 'hd720', 'hd1080', 'hd1440', 'hd2160', 'hd2880', 'highres',
        ])
-        streaming_formats = traverse_obj(streaming_data, (..., ('formats', 'adaptiveFormats'), ...))
        format_types = self._configuration_arg('formats')
        all_formats = 'duplicate' in format_types
        if self._configuration_arg('include_duplicate_formats'):
@ -3323,271 +3388,331 @@ def build_fragments(f):
                }),
            } for range_start in range(0, f['filesize'], CHUNK_SIZE))

-        for fmt in streaming_formats:
-            client_name = fmt[STREAMING_DATA_CLIENT_NAME]
-            if fmt.get('targetDurationSec'):
+        for pr in player_responses:
+            streaming_data = traverse_obj(pr, 'streamingData')
+            if not streaming_data:
                continue
+            client_name = streaming_data.get(STREAMING_DATA_CLIENT_NAME)
+            po_token = streaming_data.get(STREAMING_DATA_INITIAL_PO_TOKEN)
+            fetch_po_token = streaming_data.get(STREAMING_DATA_FETCH_PO_TOKEN)
+            innertube_context = streaming_data.get(STREAMING_DATA_INNERTUBE_CONTEXT)
+            streaming_formats = traverse_obj(streaming_data, (('formats', 'adaptiveFormats'), ...))

-            itag = str_or_none(fmt.get('itag'))
-            audio_track = fmt.get('audioTrack') or {}
-            stream_id = (itag, audio_track.get('id'), fmt.get('isDrc'))
-            if not all_formats:
-                if stream_id in stream_ids:
-                    continue
+            def get_stream_id(fmt_stream):
+                return str_or_none(fmt_stream.get('itag')), traverse_obj(fmt_stream, 'audioTrack', 'id'), fmt_stream.get('isDrc')

-            quality = fmt.get('quality')
-            height = int_or_none(fmt.get('height'))
-            if quality == 'tiny' or not quality:
-                quality = fmt.get('audioQuality', '').lower() or quality
-            # The 3gp format (17) in android client has a quality of "small",
-            # but is actually worse than other formats
-            if itag == '17':
-                quality = 'tiny'
-            if quality:
-                if itag:
-                    itag_qualities[itag] = quality
-                if height:
-                    res_qualities[height] = quality
+            def process_format_stream(fmt_stream, proto):
+                nonlocal itag_qualities, res_qualities, original_language
+                itag = str_or_none(fmt_stream.get('itag'))
+                audio_track = fmt_stream.get('audioTrack') or {}
+                quality = fmt_stream.get('quality')
+                height = int_or_none(fmt_stream.get('height'))
+                if quality == 'tiny' or not quality:
+                    quality = fmt_stream.get('audioQuality', '').lower() or quality
+                # The 3gp format (17) in android client has a quality of "small",
+                # but is actually worse than other formats
+                if itag == '17':
+                    quality = 'tiny'
+                if quality:
+                    if itag:
+                        itag_qualities[itag] = quality
+                    if height:
+                        res_qualities[height] = quality

-            display_name = audio_track.get('displayName') or ''
-            is_original = 'original' in display_name.lower()
-            is_descriptive = 'descriptive' in display_name.lower()
-            is_default = audio_track.get('audioIsDefault')
-            language_code = audio_track.get('id', '').split('.')[0]
-            if language_code and (is_original or (is_default and not original_language)):
-                original_language = language_code
+                display_name = audio_track.get('displayName') or ''
+                is_original = 'original' in display_name.lower()
+                is_descriptive = 'descriptive' in display_name.lower()
+                is_default = audio_track.get('audioIsDefault')
+                language_code = audio_track.get('id', '').split('.')[0]
+                if language_code and (is_original or (is_default and not original_language)):
+                    original_language = language_code

-            has_drm = bool(fmt.get('drmFamilies'))
+                has_drm = bool(fmt_stream.get('drmFamilies'))

-            # FORMAT_STREAM_TYPE_OTF(otf=1) requires downloading the init fragment
-            # (adding `&sq=0` to the URL) and parsing emsg box to determine the
-            # number of fragment that would subsequently requested with (`&sq=N`)
-            if fmt.get('type') == 'FORMAT_STREAM_TYPE_OTF' and not has_drm:
-                continue
-
-            if has_drm:
-                msg = f'Some {client_name} client https formats have been skipped as they are DRM protected. '
-                if client_name == 'tv':
-                    msg += (
-                        f'{"Your account" if self.is_authenticated else "The current session"} may have '
-                        f'an experiment that applies DRM to all videos on the tv client. '
-                        f'See  https://github.com/yt-dlp/yt-dlp/issues/12563  for more details.'
-                    )
-                self.report_warning(msg, video_id, only_once=True)
-
-            fmt_url = fmt.get('url')
-            if not fmt_url:
-                sc = urllib.parse.parse_qs(fmt.get('signatureCipher'))
-                fmt_url = url_or_none(try_get(sc, lambda x: x['url'][0]))
-                encrypted_sig = try_get(sc, lambda x: x['s'][0])
-                if not all((sc, fmt_url, player_url, encrypted_sig)):
-                    msg = f'Some {client_name} client https formats have been skipped as they are missing a url. '
-                    if client_name == 'web':
-                        msg += 'YouTube is forcing SABR streaming for this client. '
-                    else:
+                if has_drm:
+                    msg = f'Some {client_name} client {proto} formats have been skipped as they are DRM protected. '
+                    if client_name == 'tv':
                        msg += (
-                            f'YouTube may have enabled the SABR-only or Server-Side Ad Placement experiment for '
-                            f'{"your account" if self.is_authenticated else "the current session"}. '
+                            f'{"Your account" if self.is_authenticated else "The current session"} may have '
+                            f'an experiment that applies DRM to all videos on the tv client. '
+                            f'See  https://github.com/yt-dlp/yt-dlp/issues/12563  for more details.'
                        )
-                    msg += 'See  https://github.com/yt-dlp/yt-dlp/issues/12482  for more details'
                    self.report_warning(msg, video_id, only_once=True)
-                    continue
-                try:
-                    fmt_url += '&{}={}'.format(
-                        traverse_obj(sc, ('sp', -1)) or 'signature',
-                        self._decrypt_signature(encrypted_sig, video_id, player_url),
-                    )
-                except ExtractorError as e:
+
+                tbr = float_or_none(fmt_stream.get('averageBitrate') or fmt_stream.get('bitrate'), 1000)
+                format_duration = traverse_obj(fmt_stream, ('approxDurationMs', {float_or_none(scale=1000)}))
+                # Some formats may have much smaller duration than others (possibly damaged during encoding)
+                # E.g. 2-nOtRESiUc Ref: https://github.com/yt-dlp/yt-dlp/issues/2823
+                # Make sure to avoid false positives with small duration differences.
+                # E.g. __2ABJjxzNo, ySuUZEjARPY
+                is_damaged = try_call(lambda: format_duration < duration // 2)
+                if is_damaged:
                    self.report_warning(
-                        f'Signature extraction failed: Some formats may be missing\n'
-                        f'         player = {player_url}\n'
-                        f'         {bug_reports_message(before="")}',
-                        video_id=video_id, only_once=True)
-                    self.write_debug(
-                        f'{video_id}: Signature extraction failure info:\n'
-                        f'         encrypted sig = {encrypted_sig}\n'
-                        f'         player = {player_url}')
-                    self.write_debug(e, only_once=True)
-                    continue
+                        f'Some {client_name} client {proto} formats are possibly damaged. They will be deprioritized', video_id, only_once=True)

-            query = parse_qs(fmt_url)
-            if query.get('n'):
-                try:
-                    decrypt_nsig = self._cached(self._decrypt_nsig, 'nsig', query['n'][0])
-                    fmt_url = update_url_query(fmt_url, {
-                        'n': decrypt_nsig(query['n'][0], video_id, player_url),
-                    })
-                except ExtractorError as e:
-                    if player_url:
-                        self.report_warning(
-                            f'nsig extraction failed: Some formats may be missing\n'
-                            f'         n = {query["n"][0]} ; player = {player_url}\n'
-                            f'         {bug_reports_message(before="")}',
-                            video_id=video_id, only_once=True)
-                        self.write_debug(e, only_once=True)
-                    else:
-                        self.report_warning(
-                            'Cannot decrypt nsig without player_url: Some formats may be missing',
-                            video_id=video_id, only_once=True)
-                    continue
+                # Clients that require PO Token return videoplayback URLs that may return 403
+                require_po_token = (
+                    not po_token
+                    and _PoTokenContext.GVS in self._get_default_ytcfg(client_name)['PO_TOKEN_REQUIRED_CONTEXTS']
+                    and itag not in ['18'])  # these formats do not require PO Token

-            tbr = float_or_none(fmt.get('averageBitrate') or fmt.get('bitrate'), 1000)
-            format_duration = traverse_obj(fmt, ('approxDurationMs', {float_or_none(scale=1000)}))
-            # Some formats may have much smaller duration than others (possibly damaged during encoding)
-            # E.g. 2-nOtRESiUc Ref: https://github.com/yt-dlp/yt-dlp/issues/2823
-            # Make sure to avoid false positives with small duration differences.
-            # E.g. __2ABJjxzNo, ySuUZEjARPY
-            is_damaged = try_call(lambda: format_duration < duration // 2)
-            if is_damaged:
-                self.report_warning(
-                    'Some formats are possibly damaged. They will be deprioritized', video_id, only_once=True)
-
-            po_token = fmt.get(STREAMING_DATA_INITIAL_PO_TOKEN)
-
-            if po_token:
-                fmt_url = update_url_query(fmt_url, {'pot': po_token})
-
-            # Clients that require PO Token return videoplayback URLs that may return 403
-            require_po_token = (
-                not po_token
-                and _PoTokenContext.GVS in self._get_default_ytcfg(client_name)['PO_TOKEN_REQUIRED_CONTEXTS']
-                and itag not in ['18'])  # these formats do not require PO Token
-
-            if require_po_token and 'missing_pot' not in self._configuration_arg('formats'):
-                self._report_pot_format_skipped(video_id, client_name, 'https')
-                continue
-
-            name = fmt.get('qualityLabel') or quality.replace('audio_quality_', '') or ''
-            fps = int_or_none(fmt.get('fps')) or 0
-            dct = {
-                'asr': int_or_none(fmt.get('audioSampleRate')),
-                'filesize': int_or_none(fmt.get('contentLength')),
-                'format_id': f'{itag}{"-drc" if fmt.get("isDrc") else ""}',
-                'format_note': join_nonempty(
-                    join_nonempty(display_name, is_default and ' (default)', delim=''),
-                    name, fmt.get('isDrc') and 'DRC',
-                    try_get(fmt, lambda x: x['projectionType'].replace('RECTANGULAR', '').lower()),
-                    try_get(fmt, lambda x: x['spatialAudioType'].replace('SPATIAL_AUDIO_TYPE_', '').lower()),
-                    is_damaged and 'DAMAGED', require_po_token and 'MISSING POT',
-                    (self.get_param('verbose') or all_formats) and short_client_name(client_name),
-                    delim=', '),
-                # Format 22 is likely to be damaged. See https://github.com/yt-dlp/yt-dlp/issues/3372
-                'source_preference': (-5 if itag == '22' else -1) + (100 if 'Premium' in name else 0),
-                'fps': fps if fps > 1 else None,  # For some formats, fps is wrongly returned as 1
-                'audio_channels': fmt.get('audioChannels'),
-                'height': height,
-                'quality': q(quality) - bool(fmt.get('isDrc')) / 2,
-                'has_drm': has_drm,
-                'tbr': tbr,
-                'filesize_approx': filesize_from_tbr(tbr, format_duration),
-                'url': fmt_url,
-                'width': int_or_none(fmt.get('width')),
-                'language': join_nonempty(language_code, 'desc' if is_descriptive else '') or None,
-                'language_preference': PREFERRED_LANG_VALUE if is_original else 5 if is_default else -10 if is_descriptive else -1,
-                # Strictly de-prioritize damaged and 3gp formats
-                'preference': -10 if is_damaged else -2 if itag == '17' else None,
-            }
-            mime_mobj = re.match(
-                r'((?:[^/]+)/(?:[^;]+))(?:;\s*codecs="([^"]+)")?', fmt.get('mimeType') or '')
-            if mime_mobj:
-                dct['ext'] = mimetype2ext(mime_mobj.group(1))
-                dct.update(parse_codecs(mime_mobj.group(2)))
-            if itag:
-                itags[itag].add(('https', dct.get('language')))
-                stream_ids.append(stream_id)
-            single_stream = 'none' in (dct.get('acodec'), dct.get('vcodec'))
-            if single_stream and dct.get('ext'):
-                dct['container'] = dct['ext'] + '_dash'
-
-            if (all_formats or 'dashy' in format_types) and dct['filesize']:
-                yield {
-                    **dct,
-                    'format_id': f'{dct["format_id"]}-dashy' if all_formats else dct['format_id'],
-                    'protocol': 'http_dash_segments',
-                    'fragments': build_fragments(dct),
-                }
-            if all_formats or 'dashy' not in format_types:
-                dct['downloader_options'] = {'http_chunk_size': CHUNK_SIZE}
-                yield dct
-
-        needs_live_processing = self._needs_live_processing(live_status, duration)
-        skip_bad_formats = 'incomplete' not in format_types
-        if self._configuration_arg('include_incomplete_formats'):
-            skip_bad_formats = False
-            self._downloader.deprecated_feature('[youtube] include_incomplete_formats extractor argument is deprecated. '
-                                                'Use formats=incomplete extractor argument instead')
-
-        skip_manifests = set(self._configuration_arg('skip'))
-        if (not self.get_param('youtube_include_hls_manifest', True)
-                or needs_live_processing == 'is_live'  # These will be filtered out by YoutubeDL anyway
-                or (needs_live_processing and skip_bad_formats)):
-            skip_manifests.add('hls')
-
-        if not self.get_param('youtube_include_dash_manifest', True):
-            skip_manifests.add('dash')
-        if self._configuration_arg('include_live_dash'):
-            self._downloader.deprecated_feature('[youtube] include_live_dash extractor argument is deprecated. '
-                                                'Use formats=incomplete extractor argument instead')
-        elif skip_bad_formats and live_status == 'is_live' and needs_live_processing != 'is_live':
-            skip_manifests.add('dash')
-
-        def process_manifest_format(f, proto, client_name, itag, po_token):
-            key = (proto, f.get('language'))
-            if not all_formats and key in itags[itag]:
-                return False
-
-            if f.get('source_preference') is None:
-                f['source_preference'] = -1
-
-            # Clients that require PO Token return videoplayback URLs that may return 403
-            # hls does not currently require PO Token
-            if (
-                not po_token
-                and _PoTokenContext.GVS in self._get_default_ytcfg(client_name)['PO_TOKEN_REQUIRED_CONTEXTS']
-                and proto != 'hls'
-            ):
-                if 'missing_pot' not in self._configuration_arg('formats'):
+                if require_po_token and 'missing_pot' not in self._configuration_arg('formats'):
                    self._report_pot_format_skipped(video_id, client_name, proto)
+                    return None
+
+                name = fmt_stream.get('qualityLabel') or quality.replace('audio_quality_', '') or ''
+                fps = int_or_none(fmt_stream.get('fps')) or 0
+                dct = {
+                    'asr': int_or_none(fmt_stream.get('audioSampleRate')),
+                    'filesize': int_or_none(fmt_stream.get('contentLength')),
+                    'format_id': f'{itag}{"-drc" if fmt_stream.get("isDrc") else ""}',
+                    'format_note': join_nonempty(
+                        join_nonempty(display_name, is_default and ' (default)', delim=''),
+                        name, fmt_stream.get('isDrc') and 'DRC',
+                        try_get(fmt_stream, lambda x: x['projectionType'].replace('RECTANGULAR', '').lower()),
+                        try_get(fmt_stream, lambda x: x['spatialAudioType'].replace('SPATIAL_AUDIO_TYPE_', '').lower()),
+                        is_damaged and 'DAMAGED', require_po_token and 'MISSING POT',
+                        (self.get_param('verbose') or all_formats) and short_client_name(client_name),
+                        delim=', '),
+                    # Format 22 is likely to be damaged. See https://github.com/yt-dlp/yt-dlp/issues/3372
+                    'source_preference': (-5 if itag == '22' else -1) + (100 if 'Premium' in name else 0),
+                    'fps': fps if fps > 1 else None,  # For some formats, fps is wrongly returned as 1
+                    'audio_channels': fmt_stream.get('audioChannels'),
+                    'height': height,
+                    'quality': q(quality) - bool(fmt_stream.get('isDrc')) / 2,
+                    'has_drm': has_drm,
+                    'tbr': tbr,
+                    'filesize_approx': filesize_from_tbr(tbr, format_duration),
+                    'width': int_or_none(fmt_stream.get('width')),
+                    'language': join_nonempty(language_code, 'desc' if is_descriptive else '') or None,
+                    'language_preference': PREFERRED_LANG_VALUE if is_original else 5 if is_default else -10 if is_descriptive else -1,
+                    # Strictly de-prioritize damaged and 3gp formats
+                    'preference': -10 if is_damaged else -2 if itag == '17' else None,
+                }
+                mime_mobj = re.match(
+                    r'((?:[^/]+)/(?:[^;]+))(?:;\s*codecs="([^"]+)")?', fmt_stream.get('mimeType') or '')
+                if mime_mobj:
+                    dct['ext'] = mimetype2ext(mime_mobj.group(1))
+                    dct.update(parse_codecs(mime_mobj.group(2)))
+
+                single_stream = 'none' in (dct.get('acodec'), dct.get('vcodec'))
+                if single_stream and dct.get('ext'):
+                    dct['container'] = dct['ext'] + '_dash'
+
+                return dct
+
+            def process_sabr_formats_and_subtitles():
+                proto = 'sabr'
+                server_abr_streaming_url = (self._process_n_param
+                                            (streaming_data.get('serverAbrStreamingUrl'), video_id, player_url, proto))
+                video_playback_ustreamer_config = traverse_obj(
+                    pr, ('playerConfig', 'mediaCommonConfig', 'mediaUstreamerRequestConfig', 'videoPlaybackUstreamerConfig'))
+
+                if not server_abr_streaming_url or not video_playback_ustreamer_config:
+                    return
+
+                if protobug is None:
+                    self.report_warning(
+                        f'{video_id}: {client_name} client {proto} formats will be skipped as protobug is not installed.',
+                        only_once=True)
+                    return
+
+                sabr_config = {
+                    'video_playback_ustreamer_config': video_playback_ustreamer_config,
+                    'po_token': po_token,
+                    'fetch_po_token_fn': fetch_po_token,
+                    'client_name': client_name,
+                    'client_info': traverse_obj(innertube_context, 'client'),
+                    'reload_config_fn': functools.partial(self._reload_sabr_config, video_id, client_name),
+                    'video_id': video_id,
+                    'live_status': live_status,
+                }
+
+                for fmt_stream in streaming_formats:
+                    stream_id = get_stream_id(fmt_stream)
+                    if not all_formats:
+                        if stream_id in stream_ids:
+                            continue
+
+                    fmt = process_format_stream(fmt_stream, proto)
+                    if not fmt:
+                        continue
+
+                    caption_track = fmt_stream.get('captionTrack')
+
+                    fmt.update({
+                        'is_from_start': live_status == 'is_live' and self.get_param('live_from_start'),
+                        'url': server_abr_streaming_url,
+                        'protocol': 'sabr',
+                    })
+
+                    fmt['_sabr_config'] = {
+                        **sabr_config,
+                        'itag': stream_id[0],
+                        'xtags': fmt_stream.get('xtags'),
+                        'last_modified': fmt_stream.get('lastModified'),
+                        'target_duration_sec': fmt_stream.get('targetDurationSec'),
+                    }
+
+                    single_stream = 'none' in (fmt.get('acodec'), fmt.get('vcodec'))
+
+                    nonlocal subtitles
+                    if caption_track:
+                        # TODO: proper live subtitle extraction
+                        subtitles = self._merge_subtitles({str(stream_id[0]): [fmt]}, subtitles)
+                    elif single_stream:
+                        if stream_id[0]:
+                            itags[stream_id[0]].add((proto, fmt.get('language')))
+                            stream_ids.append(stream_id)
+                        yield fmt
+
+            def process_https_formats():
+                proto = 'https'
+                for fmt_stream in streaming_formats:
+                    if fmt_stream.get('targetDurationSec'):
+                        continue
+
+                    # FORMAT_STREAM_TYPE_OTF(otf=1) requires downloading the init fragment
+                    # (adding `&sq=0` to the URL) and parsing emsg box to determine the
+                    # number of fragment that would subsequently requested with (`&sq=N`)
+                    if fmt_stream.get('type') == 'FORMAT_STREAM_TYPE_OTF' and not bool(fmt_stream.get('drmFamilies')):
+                        continue
+
+                    stream_id = get_stream_id(fmt_stream)
+                    if not all_formats:
+                        if stream_id in stream_ids:
+                            continue
+
+                    fmt = process_format_stream(fmt_stream, proto)
+                    if not fmt:
+                        continue
+
+                    fmt_url = fmt_stream.get('url')
+                    if not fmt_url:
+                        sc = urllib.parse.parse_qs(fmt_stream.get('signatureCipher'))
+                        fmt_url = url_or_none(try_get(sc, lambda x: x['url'][0]))
+                        encrypted_sig = try_get(sc, lambda x: x['s'][0])
+                        if not all((sc, fmt_url, player_url, encrypted_sig)):
+                            continue
+                        try:
+                            fmt_url += '&{}={}'.format(
+                                traverse_obj(sc, ('sp', -1)) or 'signature',
+                                self._decrypt_signature(encrypted_sig, video_id, player_url),
+                            )
+                        except ExtractorError as e:
+                            self.report_warning(
+                                f'Signature extraction failed: Some formats may be missing\n'
+                                f'         player = {player_url}\n'
+                                f'         {bug_reports_message(before="")}',
+                                video_id=video_id, only_once=True)
+                            self.write_debug(
+                                f'{video_id}: Signature extraction failure info:\n'
+                                f'         encrypted sig = {encrypted_sig}\n'
+                                f'         player = {player_url}')
+                            self.write_debug(e, only_once=True)
+                            continue
+
+                    fmt_url = self._process_n_param(fmt_url, video_id, player_url, proto)
+                    if not fmt_url:
+                        continue
+
+                    if po_token:
+                        fmt_url = update_url_query(fmt_url, {'pot': po_token})
+
+                    fmt['url'] = fmt_url
+
+                    if stream_id[0]:
+                        itags[stream_id[0]].add((proto, fmt.get('language')))
+                        stream_ids.append(stream_id)
+
+                    if (all_formats or 'dashy' in format_types) and fmt['filesize']:
+                        yield {
+                            **fmt,
+                            'format_id': f'{fmt["format_id"]}-dashy' if all_formats else fmt['format_id'],
+                            'protocol': 'http_dash_segments',
+                            'fragments': build_fragments(fmt),
+                        }
+                    if all_formats or 'dashy' not in format_types:
+                        fmt['downloader_options'] = {'http_chunk_size': CHUNK_SIZE}
+                        yield fmt
+
+            yield from process_https_formats()
+            yield from process_sabr_formats_and_subtitles()
+
+            needs_live_processing = self._needs_live_processing(live_status, duration)
+            skip_bad_formats = 'incomplete' not in format_types
+            if self._configuration_arg('include_incomplete_formats'):
+                skip_bad_formats = False
+                self._downloader.deprecated_feature('[youtube] include_incomplete_formats extractor argument is deprecated. '
+                                                    'Use formats=incomplete extractor argument instead')
+
+            skip_manifests = set(self._configuration_arg('skip'))
+            if (not self.get_param('youtube_include_hls_manifest', True)
+                    or needs_live_processing == 'is_live'  # These will be filtered out by YoutubeDL anyway
+                    or (needs_live_processing and skip_bad_formats)):
+                skip_manifests.add('hls')
+
+            if not self.get_param('youtube_include_dash_manifest', True):
+                skip_manifests.add('dash')
+            if self._configuration_arg('include_live_dash'):
+                self._downloader.deprecated_feature('[youtube] include_live_dash extractor argument is deprecated. '
+                                                    'Use formats=incomplete extractor argument instead')
+            elif skip_bad_formats and live_status == 'is_live' and needs_live_processing != 'is_live':
+                skip_manifests.add('dash')
+
+            def process_manifest_format(f, proto, client_name, itag, po_token):
+                key = (proto, f.get('language'))
+                if not all_formats and key in itags[itag]:
                    return False
-                f['format_note'] = join_nonempty(f.get('format_note'), 'MISSING POT', delim=' ')
-                f['source_preference'] -= 20

-            itags[itag].add(key)
+                if f.get('source_preference') is None:
+                    f['source_preference'] = -1

-            if itag and all_formats:
-                f['format_id'] = f'{itag}-{proto}'
-            elif any(p != proto for p, _ in itags[itag]):
-                f['format_id'] = f'{itag}-{proto}'
-            elif itag:
-                f['format_id'] = itag
+                # Clients that require PO Token return videoplayback URLs that may return 403
+                # hls does not currently require PO Token
+                if (
+                    not po_token
+                    and _PoTokenContext.GVS in self._get_default_ytcfg(client_name)['PO_TOKEN_REQUIRED_CONTEXTS']
+                    and proto != 'hls'
+                ):
+                    if 'missing_pot' not in self._configuration_arg('formats'):
+                        self._report_pot_format_skipped(video_id, client_name, proto)
+                        return False
+                    f['format_note'] = join_nonempty(f.get('format_note'), 'MISSING POT', delim=' ')
+                    f['source_preference'] -= 20

-            if original_language and f.get('language') == original_language:
-                f['format_note'] = join_nonempty(f.get('format_note'), '(default)', delim=' ')
-                f['language_preference'] = PREFERRED_LANG_VALUE
+                itags[itag].add(key)

-            if itag in ('616', '235'):
-                f['format_note'] = join_nonempty(f.get('format_note'), 'Premium', delim=' ')
-                f['source_preference'] += 100
+                if itag and all_formats:
+                    f['format_id'] = f'{itag}-{proto}'
+                elif any(p != proto for p, _ in itags[itag]):
+                    f['format_id'] = f'{itag}-{proto}'
+                elif itag:
+                    f['format_id'] = itag

-            f['quality'] = q(itag_qualities.get(try_get(f, lambda f: f['format_id'].split('-')[0]), -1))
-            if f['quality'] == -1 and f.get('height'):
-                f['quality'] = q(res_qualities[min(res_qualities, key=lambda x: abs(x - f['height']))])
-            if self.get_param('verbose') or all_formats:
-                f['format_note'] = join_nonempty(
-                    f.get('format_note'), short_client_name(client_name), delim=', ')
-            if f.get('fps') and f['fps'] <= 1:
-                del f['fps']
+                if original_language and f.get('language') == original_language:
+                    f['format_note'] = join_nonempty(f.get('format_note'), '(default)', delim=' ')
+                    f['language_preference'] = PREFERRED_LANG_VALUE

-            if proto == 'hls' and f.get('has_drm'):
-                f['has_drm'] = 'maybe'
-                f['source_preference'] -= 5
-            return True
+                if itag in ('616', '235'):
+                    f['format_note'] = join_nonempty(f.get('format_note'), 'Premium', delim=' ')
+                    f['source_preference'] += 100

-        subtitles = {}
-        for sd in streaming_data:
-            client_name = sd[STREAMING_DATA_CLIENT_NAME]
-            po_token = sd.get(STREAMING_DATA_INITIAL_PO_TOKEN)
-            hls_manifest_url = 'hls' not in skip_manifests and sd.get('hlsManifestUrl')
+                f['quality'] = q(itag_qualities.get(try_get(f, lambda f: f['format_id'].split('-')[0]), -1))
+                if f['quality'] == -1 and f.get('height'):
+                    f['quality'] = q(res_qualities[min(res_qualities, key=lambda x: abs(x - f['height']))])
+                if self.get_param('verbose') or all_formats:
+                    f['format_note'] = join_nonempty(
+                        f.get('format_note'), short_client_name(client_name), delim=', ')
+                if f.get('fps') and f['fps'] <= 1:
+                    del f['fps']
+
+                if proto == 'hls' and f.get('has_drm'):
+                    f['has_drm'] = 'maybe'
+                    f['source_preference'] -= 5
+                return True
+
+            hls_manifest_url = 'hls' not in skip_manifests and streaming_data.get('hlsManifestUrl')
            if hls_manifest_url:
                if po_token:
                    hls_manifest_url = hls_manifest_url.rstrip('/') + f'/pot/{po_token}'
@ -3602,7 +3727,7 @@ def process_manifest_format(f, proto, client_name, itag, po_token):
                            r'/itag/(\d+)', f['url'], 'itag', default=None), po_token):
                        yield f

-            dash_manifest_url = 'dash' not in skip_manifests and sd.get('dashManifestUrl')
+            dash_manifest_url = 'dash' not in skip_manifests and streaming_data.get('dashManifestUrl')
            if dash_manifest_url:
                if po_token:
                    dash_manifest_url = dash_manifest_url.rstrip('/') + f'/pot/{po_token}'
@ -3659,11 +3784,14 @@ def _extract_storyboard(self, player_responses, duration):
                } for j in range(math.ceil(fragment_count))],
            }

-    def _download_player_responses(self, url, smuggled_data, video_id, webpage_url):
+    def _download_player_responses(self, url, smuggled_data, video_id, webpage_url, reload_playback_token=None):
        webpage = None
        if 'webpage' not in self._configuration_arg('player_skip'):
            query = {'bpctr': '9999999999', 'has_verified': '1'}
-            pp = self._configuration_arg('player_params', [None], casesense=True)[0]
+            pp = (
+                self._configuration_arg('player_params', [None], casesense=True)[0]
+                or traverse_obj(INNERTUBE_CLIENTS, ('web', 'PLAYER_PARAMS', {str}))
+            )
            if pp:
                query['pp'] = pp
            webpage = self._download_webpage_with_retries(webpage_url, video_id, query=query)
@ -3672,7 +3800,7 @@ def _download_player_responses(self, url, smuggled_data, video_id, webpage_url):

        player_responses, player_url = self._extract_player_responses(
            self._get_requested_clients(url, smuggled_data),
-            video_id, webpage, master_ytcfg, smuggled_data)
+            video_id, webpage, master_ytcfg, reload_playback_token)

        return webpage, master_ytcfg, player_responses, player_url

@ -3690,14 +3818,14 @@ def _list_formats(self, video_id, microformats, video_details, player_responses,
                       else 'was_live' if live_content
                       else 'not_live' if False in (is_live, live_content)
                       else None)
-        streaming_data = traverse_obj(player_responses, (..., 'streamingData'))
-        *formats, subtitles = self._extract_formats_and_subtitles(streaming_data, video_id, player_url, live_status, duration)
+        *formats, subtitles = self._extract_formats_and_subtitles(video_id, player_responses, player_url, live_status, duration)
+
        if all(f.get('has_drm') for f in formats):
            # If there are no formats that definitely don't have DRM, all have DRM
            for f in formats:
                f['has_drm'] = True

-        return live_broadcast_details, live_status, streaming_data, formats, subtitles
+        return live_broadcast_details, live_status, formats, subtitles

    def _real_extract(self, url):
        url, smuggled_data = unsmuggle_url(url, {})
@ -3787,8 +3915,9 @@ def feed_entry(name):
                    or int_or_none(get_first(microformats, 'lengthSeconds'))
                    or parse_duration(search_meta('duration')) or None)

-        live_broadcast_details, live_status, streaming_data, formats, automatic_captions = \
+        live_broadcast_details, live_status, formats, automatic_captions = \
            self._list_formats(video_id, microformats, video_details, player_responses, player_url, duration)
+        streaming_data = traverse_obj(player_responses, (..., 'streamingData'))
        if live_status == 'post_live':
            self.write_debug(f'{video_id}: Video is in Post-Live Manifestless mode')