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fb2k corrupts iTunes cover art
davelasker
post Nov 22 2004, 03:18
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I'm working on my own SW app for AAC files that uses faad2/mp4ff for tagging (same as fb2k). I found that calling mp4ff_meta_get_by_index to read all the tags and then calling mp4ff_meta_update to write back (modified) values corrupts the 'covr' tag used by iTunes to store album cover art.

I thought this might by a bug in my own code, but I was able to duplicate the problem in fb2k as follows:

a) add cover art with iTunes to an AAC (.m4a) file
b) open the same file with fb2k and analyze replaygain
c) go back to iTunes and the cover art no longer displays

Could it be that the cover art is a binary field with embedded 0's and the use of strlen in mp4ff_meta_update does not yield the correct length?

I couldn't find any reference to problem anywhere on the net - the closest I got was this post:
http://www.hydrogenaudio.org/forums/index....showtopic=29120

I'll do some more debugging to try to pin this down further but would appreciate it if anyone else has any insight into this problem.

Thanks for the help!

Dave

This post has been edited by davelasker: Nov 22 2004, 03:29
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kode54
post Nov 22 2004, 04:15
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It is not corrupted. It is simply ignored by the tag reader, and removed by the act of regenerating the tags with only the supported plaintext information.
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davelasker
post Nov 22 2004, 22:29
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QUOTE (kode54 @ Nov 21 2004, 08:15 PM)
It is not corrupted. It is simply ignored by the tag reader, and removed by the act of regenerating the tags with only the supported plaintext information.
*


That's not what happened to me. The corrupted 'covr' tag was left in the file.

It sure looks to me like fb2k is trying to process the mp4 'covr' tag's binary data as a utf8 string. In my original post I forgot to mention that I also got assertion failures for invalid utf-8 characters when trying to read or write the replaygain tags via fb2k.

The particular image I was using for my cover art, when added via iTunes, had a zero as the 5th data byte of the data field of the 'covr' tag. After fb2k rewrote the metadata, the 'covr' tag's length was reduced from 38KB to 4 bytes. This caused iTunes to display it as a white box.

In my own application I am going to stop using faad2's libmp4ff and switch to libmp4v2, which appears to handle mp4 binary metadata correctly (i.e. there are explicit length fields). I would humbly suggest that fb2k do the same.

For more info, see my thread in the audiocoding.com faad2 forum.

Thanks...

Dave
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tedgo
post Mar 15 2005, 19:02
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I haven't read this topic before and i used masstagger to add "auto track number" to my m4a and mp3 files i tagged with itunes or wmp10 (including cover arts). After masstagger i lost all covers stored in the files and it's very annoying - it has been more than 2000 files... sad.gif
The cover tag's still there, but itunes shows only a white box instead of the cover (and wmp for mp3 shows nothing)
Is there any solution for this annoying behaviour of foobar? I don't want to miss foobar's ingenious masstagger...
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saratoga
post Mar 15 2005, 21:37
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I don't think this is a bug. The masstagger in foobar is intended to delete all embedded images.
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tedgo
post Mar 15 2005, 21:51
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And there's no solution to around this?
When foobar's masstagger always deletes embedded images and is intended to do so, then i have to look for an other tagging solution. I don't want to miss embedded covers cos i've sorted my music as "best of the year's" and want every file with the original cover from the cd i ripped it from. I don't like the foobar solution (one cover in the folder for every file in it).
So i must "renumber" my files by hand in the future (puh, what an effort...) dry.gif
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Florian
post Mar 15 2005, 22:00
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QUOTE (tedgo @ Mar 15 2005, 09:51 PM)
So i must "renumber" my files by hand in the future (puh, what an effort...)  dry.gif
*

No. You don't have to do this by hand - there are taggers out there which support renumbering and cover images.


--------------------
Mp3tag - universal multi-format tag editor
http://www.mp3tag.de/en/
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tedgo
post Mar 15 2005, 22:08
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With a function like foobar's "auto track number"? And perhaps some other goodies like foobar's masstagger and similar tagging options (like custom fields like "cpopyright", "composer" and so on)? AND support for cover images? Freeware? huh.gif
I don't know one. Could you please give me a link?

This post has been edited by tedgo: Mar 15 2005, 22:19
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richter
post Mar 15 2005, 23:22
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Same issue happens with MP3 files. I tagged them in MediaMonkey and once Foobar2000 scaned those files and added replaygain info coverart doesn't display anymore. Even after re-downloading cover art for some files, they tend to disappear if you switch between foobar2000 and Media Monkey, although I would just play them in foobar and not tag them.
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tedgo
post Mar 16 2005, 11:15
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I hope there will be support for embedded images in the near future in foobar2000.
This would be great.
Now i decided to first renumber my files in foobar2000 and add cover arts later with "audioshell 1.0" for the next time. But it's too late for my about 10,000 files i saved to my "HD-Media Library" until now...
Good that i noticed it on the first 2,000 files, so i can renumber the other files with an other program. But which program is able to do (especially for aac) with preserving all other tags (like copyright, comments and composer/writer tags)?
"MP3tag" doesn't seem to handle these "custom" tags, "Media Tagger" 1.3.5 can't save the mp4 tags...
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Florian
post Mar 16 2005, 12:11
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QUOTE (tedgo @ Mar 16 2005, 11:15 AM)
"MP3tag" doesn't seem to handle these "custom" tags.
*

Mp3tag has full support for these custom tag fields via the extended tag dialog ("View, Tags..." or Alt+T) or directly by adding a column for the tag field to the file view ("View, Columns...").

Best regards,
~ Florian


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http://www.mp3tag.de/en/
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ATWindsor
post Mar 16 2005, 18:02
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QUOTE (Mike Giacomelli @ Mar 15 2005, 12:37 PM)
I don't think this is a bug.  The masstagger in foobar is intended to delete all embedded images.
*


Is this feature planned to continue in the next version? I must admit that I don't like the fact that the user can't decide for himself what tag-info to remove from files.

AtW
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tedgo
post Mar 16 2005, 18:11
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@Ganymed
Thank you. I'll try it.
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