Bring MutagenMetadataPP back

This reverts commit 2598790093.

yt_dlp/__init__.py

@@ -670,6 +670,11 @@ def get_postprocessors(opts):
             'add_metadata': opts.addmetadata,
             'add_infojson': opts.embed_infojson,
         }
+    # MutagenMetadata must run after FFmpegMetadata
+    if opts.addmetadata:
+        yield {
+            'key': 'MutagenMetadata',
+        }
     # Deprecated
     # This should be above EmbedThumbnail since sponskrub removes the thumbnail attachment
     # but must be below EmbedSubtitle and FFmpegMetadata

yt_dlp/postprocessor/__init__.py

@@ -30,6 +30,7 @@
 )
 from .modify_chapters import ModifyChaptersPP
 from .movefilesafterdownload import MoveFilesAfterDownloadPP
+from .mutagenmetadata import MutagenMetadataPP
 from .sponskrub import SponSkrubPP
 from .sponsorblock import SponsorBlockPP
 from .xattrpp import XAttrMetadataPP

yt_dlp/postprocessor/mutagenmetadata.py

@@ -0,0 +1,42 @@
+from .common import PostProcessor
+from ..dependencies import mutagen
+
+if mutagen:
+    from mutagen.easymp4 import EasyMP4
+    from mutagen.flac import FLAC
+    from mutagen.mp3 import EasyMP3
+    from mutagen.musepack import Musepack
+    from mutagen.oggopus import OggOpus
+    from mutagen.oggvorbis import OggVorbis
+
+
+class MutagenMetadataPP(PostProcessor):
+    def __init__(self, downloader):
+        PostProcessor.__init__(self, downloader)
+
+    @PostProcessor._restrict_to(images=False)
+    def run(self, information):
+        extension = information['ext']
+        ret = [], information
+        if not mutagen:
+            if extension in ['mp3', 'm4a', 'ogg', 'opus', 'flac', '.mpc']:
+                self.report_warning('module mutagen was not found. Tags with multiple values (e.g. artist, album artist and genre) may be set incorrectly. Please install using `python -m pip install mutagen`')
+            return ret
+        tag_mapping = {
+            'artist': 'artists',
+            'albumartist': 'album_artists',
+            'genre': 'genres',
+            'composer': 'composers'
+        }
+        supported_formats = [EasyMP3, EasyMP4, OggVorbis, OggOpus, FLAC, Musepack]
+        file = mutagen.File(information['filepath'], supported_formats)
+        if not file:
+            return ret
+        if isinstance(file, EasyMP4):
+            file.RegisterTextKey('composer', '\251wrt')
+        for tag_key, info_key in tag_mapping.items():
+            value = information.get(info_key)
+            if value:
+                file[tag_key] = value
+        file.save()
+        return ret