Add compat-option embed-metadata

README.md

@@ -137,6 +137,7 @@ ### Differences in default behavior
 * `--ignore-errors` is enabled by default. Use `--abort-on-error` or `--compat-options abort-on-error` to abort on errors instead
 * When writing metadata files such as thumbnails, description or infojson, the same information (if available) is also written for playlists. Use `--no-write-playlist-metafiles` or `--compat-options no-playlist-metafiles` to not write these files
 * `--add-metadata` attaches the `infojson` to `mkv` files in addition to writing the metadata when used with `--write-infojson`. Use `--compat-options no-attach-info-json` to revert this
+* Some metadata are embedded into different fields when using `--add-metadata` as compared to youtube-dl. Most notably, `comment` field contains the `webpage_url` and `synopsis` contains the `description`. You can [use `--parse-metadata`](https://github.com/yt-dlp/yt-dlp#modifying-metadata) to modify this to your liking or use `--compat-options embed-metadata` to revert this
 * `playlist_index` behaves differently when used with options like `--playlist-reverse` and `--playlist-items`. See [#302](https://github.com/yt-dlp/yt-dlp/issues/302) for details. You can use `--compat-options playlist-index` if you want to keep the earlier behavior
 * The output of `-F` is listed in a new format. Use `--compat-options list-formats` to revert this
 * All *experiences* of a funimation episode are considered as a single video. This behavior breaks existing archives. Use `--compat-options seperate-video-versions` to extract information from only the default player

yt_dlp/options.py

@@ -278,7 +278,7 @@ def _dict_from_options_callback(
             'allowed_values': {
                 'filename', 'format-sort', 'abort-on-error', 'format-spec', 'no-playlist-metafiles',
                 'multistreams', 'no-live-chat', 'playlist-index', 'list-formats', 'no-direct-merge',
-                'no-youtube-channel-redirect', 'no-youtube-unavailable-videos', 'no-attach-info-json',
+                'no-youtube-channel-redirect', 'no-youtube-unavailable-videos', 'no-attach-info-json', 'embed-metadata',
                 'embed-thumbnail-atomicparsley', 'seperate-video-versions', 'no-clean-infojson', 'no-keep-subs',
             }, 'aliases': {
                 'youtube-dl': ['-multistreams', 'all'],

yt_dlp/postprocessor/ffmpeg.py

@@ -721,6 +721,9 @@ def add(meta_list, info_list=None):
         add('season_number')
         add('episode_id', ('episode', 'episode_id'))
         add('episode_sort', 'episode_number')
+        if 'embed-metadata' in self.get_param('compat_opts', []):
+            add('comment', 'description')
+            metadata.pop('synopsis', None)
 
         for key, value in info.items():
             if value is not None and key != meta_prefix and key.startswith(meta_prefix):