ID3: Support reading multiple COMM frames

[GoogleCodeExporter]

It appears, when reading tags from an MP3 through scripts using mutagen, or 
when using mid3v2, I only get the last COMM frame from the file.  For example, 
this is what mid3v2 displays for a file given three comments in foobar2000:

[dave@nymph Ant Videos]$ mid3v2 00\ -\ Little\ Sur.mp3
IDv2 tag info for 00 - Little Sur.mp3:
COMM=='eng'=https://soundcloud.com/jhnmyr/little-sur
TALB=[non-album tracks]
TCOM=John Mayer
TIT2=Little Sur
TMCL=[unrepresentable data]
TPE1=John Mayer
TSOP=Mayer, John
TXXX=MusicBrainz Artist Id=144ef525-85e9-40c3-8335-02c32d0861f3
TXXX=MusicBrainz Work Id=869a9d8f-15e4-471a-a2bd-19078d15b639
UFID=http://musicbrainz.org=62a1f0f6-77e5-4111-a219-40577333daed

[dave@nymph Ant Videos]$ id3ted -l 00\ -\ Little\ Sur.mp3 
ID3v2.4 - 12 frames:
TIT2: Little Sur
TPE1: John Mayer
TALB: [non-album tracks]
UFID: 
TMCL: electric bass guitar Pino Palladino piano Chick Corea electric guitar 
John Mayer drums Steve Jordan trumpet Wallace Roney
TSOP: Mayer, John
TXXX: [MusicBrainz Artist Id]: 144ef525-85e9-40c3-8335-02c32d0861f3
TXXX: [MusicBrainz Work Id]: 869a9d8f-15e4-471a-a2bd-19078d15b639
TCOM: John Mayer
COMM: [](eng): Recorded on 2014-02-22.
COMM: [](eng): Released to soundcloud and tumblr on 2014-03-10.
COMM: [](eng): https://soundcloud.com/jhnmyr/little-sur

I sure this is because the ID3 spec says "There may be more than one comment 
frame in each tag, but only one with the same language and content descriptor." 
 Nevertheless, some software (foobar2000) is writing them, so I propose that 
mutagen support reading (but not writing) them.

Original issue reported on code.google.com by dgasa...@gmail.com on 12 Mar 2014 at 4:02

[GoogleCodeExporter]

mutagen has moved to Bitbucket: https://bitbucket.org/lazka/mutagen/issue/172

Original comment by reiter.christoph@gmail.com on 4 Jul 2014 at 3:32

• Changed state: Duplicate