added support for MP4 files

symuid

@@ -9,15 +9,15 @@ import subprocess
 
 # http://id3.org/id3v2.4.0-frames#4.1.
 TRACK_UUID_ID3_OWNER_ID = 'symuid'
-
-# TODO http://mutagen.readthedocs.io/en/latest/api/mp4.html
-
+# freeform keys start with '----'
+# http://mutagen.readthedocs.io/en/latest/api/mp4.html
+TRACK_UUID_MP4_TAG = '----:symuid:uuid'
 
 def generate_uuid():
     return subprocess.check_output(['uuid', '-v', '4', '-F', 'BIN']).strip()
 
 
-def get_uuid(id3_tags):
+def get_uuid_id3(id3_tags):
     assert isinstance(id3_tags, mutagen.id3.ID3), type(id3_tags)
     ufids = id3_tags.getall('UFID')
     for ufid in ufids:
@@ -26,8 +26,8 @@ def get_uuid(id3_tags):
     return None
 
 
-def get_or_assign_uuid(id3_tags):
-    uuid = get_uuid(id3_tags)
+def get_or_assign_uuid_id3(id3_tags):
+    uuid = get_uuid_id3(id3_tags)
     if uuid is None:
         # mutagen.id3._specs.EncodedTextSpec.write encodes 'owner'
         id3_tags.add(mutagen.id3.UFID(
@@ -36,11 +36,25 @@ def get_or_assign_uuid(id3_tags):
         ))
         id3_tags.save()
         id3_tags.load(filename=id3_tags.filename)
-        uuid = get_uuid(id3_tags)
+        uuid = get_uuid_id3(id3_tags)
         print("{!r}: assigned uuid {!r}".format(id3_tags.filename, uuid))
         assert uuid is not None
     return uuid
 
+def get_or_assign_uuid_mp4(mp4_file):
+    if not TRACK_UUID_MP4_TAG in mp4_file:
+        mp4_file[TRACK_UUID_MP4_TAG] = mutagen.mp4.MP4FreeForm(
+            data=generate_uuid(),
+            # https://mutagen.readthedocs.io/en/latest/api/mp4.html#mutagen.mp4.AtomDataType.UUID
+            dataformat= mutagen.mp4.AtomDataType.UUID,
+        )
+        mp4_file.save()
+        mp4_file.load(filename=mp4_file.filename)
+        print("{!r}: assigned uuid {!r}".format(
+            mp4_file.filename, mp4_file[TRACK_UUID_MP4_TAG][0],
+        ))
+    return mp4_file[TRACK_UUID_MP4_TAG][0]
+
 
 def symuid(path):
     if os.path.isdir(path):
@@ -54,10 +68,12 @@ def symuid(path):
             raise Exception(path)
         if not f:
             print("{!r}: unsupported filetype, ignored".format(path))
-        elif isinstance(f.tags, mutagen.mp4.MP4Tags):
-            print("{!r}: mp4 tags not supported, ignored".format(path))
+        elif isinstance(f, mutagen.mp4.MP4):
+            get_or_assign_uuid_mp4(f)
+        elif isinstance(f.tags, mutagen.id3.ID3):
+            get_or_assign_uuid_id3(f.tags)
         else:
-            get_or_assign_uuid(f.tags)
+            raise Exception(f)
 
 
 def _init_argparser():