sane-tag-music: support mp4/m4a; support "producer" tag (grouping) for mp3/mp4

pkgs/additional/sane-scripts/src/sane-tag-music

@@ -10,16 +10,20 @@
 #   - Artist
 #   - Organization (i.e. record label)
 #   - Performer
-#   - Producer
+#   - Producer  (N.B.: mutagen supports this for FLAC, but not mp3 or mp4)
 #   - Title
 #   - TrackNumber
 # - ID3 (mp3): <https://www.exiftool.org/TagNames/ID3.html>
+#   - <https://docs.mp3tag.de/mapping/>
 #   - Album
-#   - AlbumArtist  (??)
+#   - AlbumArtist
 #   - Artist
 #   - Band
 #   - Conductor
+#   - Composer  (?)
+#   - Grouping
 #   - InterpretedBy
+#   - Publisher  (N.B.: mutagen doesn't support this for mp4)
 #   - Subtitle
 #   - Title
 #   - Track
@@ -86,6 +90,7 @@ import os.path
 import mutagen.easyid3
 import mutagen.flac
 import mutagen.mp3
+import mutagen.easymp4
 import mutagen.oggopus
 import mutagen.oggvorbis
 import pykakasi
@@ -522,23 +527,27 @@ class AudioFile(MediaFile):
     def __init__(self, path_: str):
         super().__init__(path_)
         self.muta = None
+        self.producer_field_name = "producer"
 
-        _base, ext = os.path.splitext(path_)
+        ext = self.ext
         try:
             # TODO: handle:
-            # - .m4a
             # - .wav
             # - .wma
-            if ext == '.flac':
+            if ext == 'flac':
                 self.muta = mutagen.flac.Open(path_)
-            elif ext == '.aac':
+            elif ext == 'aac':
                 # TODO: this seems to only read tags, and not create them?
                 self.muta = mutagen.easyid3.EasyID3(path_)
-            elif ext == '.mp3':
+            elif ext == 'mp3':
+                self.producer_field_name = "grouping"
                 self.muta = mutagen.mp3.EasyMP3(path_)
-            elif ext == '.ogg':
+            elif ext in [ 'm4a', 'mp4' ]:
+                self.producer_field_name = "grouping"
+                self.muta = mutagen.easymp4.EasyMP4(path_)
+            elif ext in 'ogg':
                 self.muta = mutagen.oggvorbis.OggVorbis(path_)
-            elif ext == '.opus':
+            elif ext == 'opus':
                 self.muta = mutagen.oggopus.OggOpus(path_)
             else:
                 logger.debug(f"no metadata handler for {path_}")
@@ -550,7 +559,7 @@ class AudioFile(MediaFile):
             album=self.muta.get('album', []) if self.muta else [],
             albumartist=self.muta.get('albumartist', []) if self.muta else [],
             artist=self.muta.get('artist', []) if self.muta else [],
-            producer=self.muta.get('producer', []) if self.muta else [],
+            producer=self.muta.get(self.producer_field_name, []) if self.muta else [],
             title=self.muta.get('title', []) if self.muta else [],
             tracknumber=self.muta.get('tracknumber', []) if self.muta else [],
         )
@@ -569,7 +578,7 @@ class AudioFile(MediaFile):
         set_tag('album', tags.album)
         set_tag('albumartist', tags.albumartist)
         set_tag('artist', tags.artist)
-        set_tag('producer', tags.producer)
+        set_tag(self.producer_field_name, tags.producer)
         set_tag('title', tags.title)
         set_tag('tracknumber', tags.tracknumber)