[EmbedThumbnail] Add compat-option `embed-thumbnail-atomicparsley`

to force use of atomicparsley for embedding thumbnails in mp4

Related: #411

README.md

@@ -131,6 +131,7 @@ Some of yt-dlp's default options are different from that of youtube-dl and youtu
 * Youtube channel URLs are automatically redirected to `/video`. Append a `/featured` to the URL to download only the videos in the home page. If the channel does not have a videos tab, we try to download the equivalent `UU` playlist instead. Also, `/live` URLs raise an error if there are no live videos instead of silently downloading the entire channel. You may use `--compat-options no-youtube-channel-redirect` to revert all these redirections
 * Unavailable videos are also listed for youtube playlists. Use `--compat-options no-youtube-unavailable-videos` to remove this
 * If `ffmpeg` is used as the downloader, the downloading and merging of formats happen in a single step when possible. Use `--compat-options no-direct-merge` to revert this
+* Thumbnail embedding in `mp4` is done with mutagen if possible. Use `--compat-options embed-thumbnail-atomicparsley` to force the use of AtomicParsley instead
 
 For ease of use, a few more compat options are available:
 * `--compat-options all`: Use all compat options

yt_dlp/YoutubeDL.py

@@ -391,8 +391,9 @@ class YoutubeDL(object):
     compat_opts:       Compatibility options. See "Differences in default behavior".
                        Note that only format-sort, format-spec, no-live-chat,
                        no-attach-info-json, playlist-index, list-formats,
-                       no-direct-merge, no-youtube-channel-redirect,
+                       no-direct-merge, embed-thumbnail-atomicparsley,
-                       and no-youtube-unavailable-videos works when used via the API
+                       no-youtube-unavailable-videos, no-youtube-channel-redirect,
+                       works when used via the API
 
     The following parameters are not used by YoutubeDL itself, they are used by
     the downloader (see yt_dlp/downloader/common.py):

yt_dlp/__init__.py

@@ -268,6 +268,7 @@ def _real_main(argv=None):
         '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',
+        'embed-thumbnail-atomicparsley',
     ]
     compat_opts = parse_compat_opts()
 

yt_dlp/postprocessor/embedthumbnail.py

@@ -125,8 +125,9 @@ class EmbedThumbnailPP(FFmpegPostProcessor):
             self.run_ffmpeg(filename, temp_filename, options)
 
         elif info['ext'] in ['m4a', 'mp4', 'mov']:
+            prefer_atomicparsley = 'embed-thumbnail-atomicparsley' in self.get_param('compat_opts', [])
             # Method 1: Use mutagen
-            if not has_mutagen:
+            if not has_mutagen or prefer_atomicparsley:
                 success = False
             else:
                 try:
@@ -145,7 +146,7 @@ class EmbedThumbnailPP(FFmpegPostProcessor):
                     success = False
 
             # Method 2: Use ffmpeg+ffprobe
-            if not success:
+            if not success and not prefer_atomicparsley:
                 success = True
                 try:
                     options = ['-c', 'copy', '-map', '0', '-dn', '-map', '1']