Allow --exec to be run at any post-processing stage

Deprecates `--exec-before-download`

yt_dlp/YoutubeDL.py

@@ -91,6 +91,7 @@ from .utils import (
     PerRequestProxyHandler,
     platform_name,
     Popen,
+    POSTPROCESS_WHEN,
     PostProcessingError,
     preferredencoding,
     prepend_extension,
@@ -507,7 +508,7 @@ class YoutubeDL(object):
 
     params = None
     _ies = {}
-    _pps = {'pre_process': [], 'before_dl': [], 'after_move': [], 'post_process': []}
+    _pps = {k: [] for k in POSTPROCESS_WHEN}
     _printed_messages = set()
     _first_webpage_request = True
     _download_retcode = None
@@ -525,7 +526,7 @@ class YoutubeDL(object):
             params = {}
         self._ies = {}
         self._ies_instances = {}
-        self._pps = {'pre_process': [], 'before_dl': [], 'after_move': [], 'post_process': []}
+        self._pps = {k: [] for k in POSTPROCESS_WHEN}
         self._printed_messages = set()
         self._first_webpage_request = True
         self._post_hooks = []

yt_dlp/__init__.py

@@ -143,6 +143,8 @@ def _real_main(argv=None):
             '"-f best" selects the best pre-merged format which is often not the best option',
             'To let yt-dlp download and merge the best available formats, simply do not pass any format selection',
             'If you know what you are doing and want only the best pre-merged format, use "-f b" instead to suppress this warning')))
+    if opts.exec_cmd.get('before_dl') and opts.exec_before_dl_cmd:
+        parser.error('using "--exec-before-download" conflicts with "--exec before_dl:"')
     if opts.usenetrc and (opts.username is not None or opts.password is not None):
         parser.error('using .netrc conflicts with giving username/password')
     if opts.password is not None and opts.username is None:
@@ -489,13 +491,6 @@ def _real_main(argv=None):
             # Run this before the actual video download
             'when': 'before_dl'
         })
-    # Must be after all other before_dl
-    if opts.exec_before_dl_cmd:
-        postprocessors.append({
-            'key': 'Exec',
-            'exec_cmd': opts.exec_before_dl_cmd,
-            'when': 'before_dl'
-        })
     if opts.extractaudio:
         postprocessors.append({
             'key': 'FFmpegExtractAudio',
@@ -596,13 +591,15 @@ def _real_main(argv=None):
     # XAttrMetadataPP should be run after post-processors that may change file contents
     if opts.xattrs:
         postprocessors.append({'key': 'XAttrMetadata'})
-    # Exec must be the last PP
-    if opts.exec_cmd:
+    # Exec must be the last PP of each category
+    if opts.exec_before_dl_cmd:
+        opts.exec_cmd.setdefault('before_dl', opts.exec_before_dl_cmd)
+    for when, exec_cmd in opts.exec_cmd.items():
         postprocessors.append({
             'key': 'Exec',
-            'exec_cmd': opts.exec_cmd,
+            'exec_cmd': exec_cmd,
             # Run this only after the files have been moved to their final locations
-            'when': 'after_move'
+            'when': when,
         })
 
     def report_args_compat(arg, name):

yt_dlp/options.py

@@ -16,6 +16,7 @@ from .utils import (
     expand_path,
     get_executable_path,
     OUTTMPL_TYPES,
+    POSTPROCESS_WHEN,
     preferredencoding,
     remove_end,
     write_string,
@@ -1393,29 +1394,33 @@ def parseOpts(overrideArguments=None):
         dest='ffmpeg_location',
         help='Location of the ffmpeg binary; either the path to the binary or its containing directory')
     postproc.add_option(
-        '--exec', metavar='CMD',
-        action='append', dest='exec_cmd',
-        help=(
-            'Execute a command on the file after downloading and post-processing. '
+        '--exec',
+        metavar='[WHEN:]CMD', dest='exec_cmd', default={}, type='str',
+        action='callback', callback=_dict_from_options_callback,
+        callback_kwargs={
+            'allowed_keys': '|'.join(map(re.escape, POSTPROCESS_WHEN)),
+            'default_key': 'after_move',
+            'multiple_keys': False,
+            'append': True,
+        }, help=(
+            'Execute a command, optionally prefixed with when to execute it (after_move if unspecified), separated by a ":". '
+            'Supported values of "WHEN" are the same as that of --use-postprocessor. '
             'Same syntax as the output template can be used to pass any field as arguments to the command. '
-            'An additional field "filepath" that contains the final path of the downloaded file is also available. '
-            'If no fields are passed, %(filepath)q is appended to the end of the command. '
+            'After download, an additional field "filepath" that contains the final path of the downloaded file '
+            'is also available, and if no fields are passed, %(filepath)q is appended to the end of the command. '
             'This option can be used multiple times'))
     postproc.add_option(
         '--no-exec',
-        action='store_const', dest='exec_cmd', const=[],
+        action='store_const', dest='exec_cmd', const={},
         help='Remove any previously defined --exec')
     postproc.add_option(
         '--exec-before-download', metavar='CMD',
         action='append', dest='exec_before_dl_cmd',
-        help=(
-            'Execute a command before the actual download. '
-            'The syntax is the same as --exec but "filepath" is not available. '
-            'This option can be used multiple times'))
+        help=optparse.SUPPRESS_HELP)
     postproc.add_option(
         '--no-exec-before-download',
         action='store_const', dest='exec_before_dl_cmd', const=[],
-        help='Remove any previously defined --exec-before-download')
+        help=optparse.SUPPRESS_HELP)
     postproc.add_option(
         '--convert-subs', '--convert-sub', '--convert-subtitles',
         metavar='FORMAT', dest='convertsubtitles', default=None,

yt_dlp/postprocessor/exec.py

@@ -22,11 +22,13 @@ class ExecPP(PostProcessor):
         if tmpl_dict:  # if there are no replacements, tmpl_dict = {}
             return self._downloader.escape_outtmpl(tmpl) % tmpl_dict
 
-        # If no replacements are found, replace {} for backard compatibility
-        if '{}' not in cmd:
-            cmd += ' {}'
-        return cmd.replace('{}', compat_shlex_quote(
-            info.get('filepath') or info['_filename']))
+        filepath = info.get('filepath', info.get('_filename'))
+        # If video, and no replacements are found, replace {} for backard compatibility
+        if filepath:
+            if '{}' not in cmd:
+                cmd += ' {}'
+            cmd = cmd.replace('{}', compat_shlex_quote(filepath))
+        return cmd
 
     def run(self, info):
         for tmpl in self.exec_cmd:

yt_dlp/utils.py

@@ -3036,6 +3036,9 @@ def qualities(quality_ids):
     return q
 
 
+POSTPROCESS_WHEN = {'pre_process', 'before_dl', 'after_move', 'post_process'}
+
+
 DEFAULT_OUTTMPL = {
     'default': '%(title)s [%(id)s].%(ext)s',
     'chapter': '%(title)s - %(section_number)03d %(section_title)s [%(id)s].%(ext)s',