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mp3 tag reading problems...

Posted: Mon May 21, 2007 4:34 pm
by danjewett
...hello. First time visitor.

I've been using a variety of different apps for tagging mp3s mainly iTunes and Media Rage.

As I import mp3s to the Play library there are always some (usually an album set) that don't show their tags properly in the file list. The tags are showing up properly in other applications but in Play I'm getting at most 'format' and 'duration'.

The only way I've been able to fix this is to convert to v1.1 tags (or just drop the v2.3 tags) and then add the v2.3 tags back. A drag because of truncation, lost artwork, etc.

I don't think the problem is with iTunes or Rage because adding the tags back with either of those apps produces readable tags in Play.

Changing between v2 tags (to v2.2, or 2.4) and back doesn't work, and I can't seem to find anything about the files themselves that is causing this to happen.

Any ideas?

FLAC file tags are working just fine.

Thanks for a great alternative format player!

Dan J.

Posted: Tue May 22, 2007 12:00 am
by sbooth
Could you send me one of the files that isn't working so I can take a look at it?

Posted: Tue May 22, 2007 1:54 pm
by danjewett
sbooth wrote:Could you send me one of the files that isn't working so I can take a look at it?
I've sent one as an email attachment. It's 3.1MB. Let me know if it needs to be smaller.

Dan J.

Posted: Wed May 23, 2007 1:15 am
by sbooth
The problem with these files is that they contain an illegal (and unusual) ID3v2.3 tag: 'CM1 '. The ID3v2.3 spec says that:
The frame ID made out of the characters capital A-Z and 0-9. Identifiers beginning with "X", "Y" and "Z" are for experimental use and free for everyone to use, without the need to set the experimental bit in the tag header. Have in mind that someone else might have used the same identifier as you. All other identifiers are either used or reserved for future use.
so the space at the end of the frame is illegal. TagLib (which Play uses for reading ID3 tags) stops parsing if it encounters an illegal tag.

I'm not sure if it would be worth altering TagLib to ignore illegal frames, as this is a good sanity-check against malformed files (and possible overwrites of data). Otherwise, the files are perfectly fine MP3 files with valid ID3v2.3 tag information.

Posted: Wed May 23, 2007 7:06 pm
by danjewett
I suspected it was something about malformed tag structure. I guess iTunes and Media Rage aren't bothered by the illegal tag.

Media Rage has a tool for exporting/importing tag data to/from xml maybe I can figure out a way to fix these using MR instead of having to redo all the data.

Thanks for looking in to it.

Dan J.