Current support for MP4 (AAC) audio-only files is pretty spotty in TMH.
Hmm, if we want the "codecs" generation to be somewhat accurate, it seems we will have to fix getID3.
avc1 . followed by three bytes 1: profile_idc 2: the byte containing the constraint_set flags 3: level_idc.
These bytes are in the moov.trak.mdia.minf.stbl.stsd.avc1.avcC atom, which apparently isn't read by getID3
[mpv4|mp4a] . ObjectTypeIndication . [ProfileLevelIndication|AudioObjectTypeIndication]