diff --git a/yt_dlp/postprocessor/ffmpeg.py b/yt_dlp/postprocessor/ffmpeg.py
index 59a49aa57..881900e10 100644
--- a/yt_dlp/postprocessor/ffmpeg.py
+++ b/yt_dlp/postprocessor/ffmpeg.py
@@ -28,6 +28,7 @@
     prepend_extension,
     replace_extension,
     shell_quote,
+    strftime_or_none,
     traverse_obj,
     variadic,
     write_json_file,
@@ -736,12 +737,12 @@ def _get_metadata_opts(self, info):
         meta_prefix = 'meta'
         metadata = collections.defaultdict(dict)
 
-        def add(meta_list, info_list=None):
+        def add(meta_list, info_list=None, convert=str):
             value = next((
                 info[key] for key in [f'{meta_prefix}_', *variadic(info_list or meta_list)]
                 if info.get(key) is not None), None)
             if value not in ('', None):
-                value = ', '.join(map(str, variadic(value)))
+                value = ', '.join(map(convert, variadic(value)))
                 value = value.replace('\0', '')  # nul character cannot be passed in command line
                 metadata['common'].update(dict.fromkeys(variadic(meta_list), value))
 
@@ -751,7 +752,7 @@ def add(meta_list, info_list=None):
         # https://kodi.wiki/view/Video_file_tagging
 
         add('title', ('track', 'title'))
-        add('date', 'upload_date')
+        add('date', ('release_date', 'upload_date'), convert=strftime_or_none(date_format='%Y-%m-%d'))
         add(('description', 'synopsis'), 'description')
         add(('purl', 'comment'), 'webpage_url')
         add('track', 'track_number')
diff --git a/yt_dlp/utils/_utils.py b/yt_dlp/utils/_utils.py
index 20aa341ca..38f49d0f3 100644
--- a/yt_dlp/utils/_utils.py
+++ b/yt_dlp/utils/_utils.py
@@ -2047,6 +2047,7 @@ def url_or_none(url):
     return url if re.match(r'(?:(?:https?|rt(?:m(?:pt?[es]?|fp)|sp[su]?)|mms|ftps?|wss?):)?//', url) else None
 
 
+@partial_application
 def strftime_or_none(timestamp, date_format='%Y%m%d', default=None):
     datetime_object = None
     try: