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Topic: BUG: Tag Studio Can't Fix VBR Header, Tag Studio Can't Fix VBR Header< Next Oldest | Next Newest >
mikla
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Posted: May 01 2003,04:36
I split an mp3 with MP3 Surgeon 2.2.  The resulting file works and plays in WinAmp, but reports the incorrect time.  From what I've read, this is a result of a bad VBR header.  The suggested solution (not to this specific software output, but this problem) was to use MP3 Tag Studio.  When I try to repair it with VBR Header Repair/Add checked (Only process real VBR files has no effect either way), I get the error:

"MP3 headers out of sync for file xyz.mp3, aborting!
 Repair failed for file xyz.mp3"

I really don't care if the header is fixed, I just want a correct header on the file, but there does not appear to be a "remove offending header" feature.

This is the only reason I need this program.  If this problem is fixed, I will be interested in purchasing it.

If you (the author of MP3 Tag Studio) are interested in a copy of one of these files, please let me know at mda_brading@aichlmayr.net and I will send you one.
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Magnus Brading
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Posted: May 01 2003,14:07
To be able to create a VBR header, the program has to traverse all the so called "mp3 frames" in the entire file. Each such frame has a header, and it is needed to be able to find the subsequent frame. The error message you report indicates that some of these frame headers are corrupted in your file (most likely due to a non-frame-clean cut by that other program). I suggest you use the trim feature of Mp3/Tag Studio to split that file, and then you should be able to create the VBR header too (if the frame corruption isn't already present in the file from the start, in that case you will need to fix it with some other program first).

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mikla
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Posted: May 01 2003,15:44
Hmmm...  I was under the impression that LAME was a pretty clean encoder.  I tried doing a cut using MP3 Tag Studio, and when I check "Frame Count Mode (Variable Bit Rate)" and click "Update Cut Info", I get the error, "Lost Header Sync, File Is Most Probably Corrupt, Aborting!"

I tried re-encoding the wav file, and it doesn't help, so the file is only corrupt if LAME wrote it that way.

I don't understand how the player plays the file if the frames have bad headers.
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Magnus Brading
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Posted: May 01 2003,18:28
Most players are quite forgiving when it comes to corrupted data in mp3:s. If they come upon it, they search the data linearly and analyze it until they find a good frame header again. I could do that to, but it's just not implemented right now.

But like you say, there's something fishy if the file is taken directly out of LAME (without cutting it inbetween?) and you get that error message. I can take a look at a sample file if you send it to me (I just sent a mail to the address you gave above).

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Disposable Hero
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Posted: May 01 2003,19:06
I ran into a problem like this and traced it to LAME generating incorrect duration info for VBR files. MP3Trim performs a full header scan and corrects this.
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Magnus Brading
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Posted: May 01 2003,20:20
Thanks for the insight Disposable Hero. Further correspondence with mikla seems to indicate that the problem is in the original mp3 file in this case too.

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mikla
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Posted: May 02 2003,05:44
I have an update.  It turns out that the problem is specific to the 3.93 and 3.93.1 LAME encoders.  Apparently those versions have a problem with large wav/mp3 files where some small percentage (about 3 meg out of 70 meg in this case) gets splattered over the rest of the file instead of being placed in stream where it belongs.

I have only my own empirical evidence to prove this--it seems to be a mystery to the experts I've consulted--but the problem is easily reproduced.

The problem was solved by backing down to version 3.90.3 APE.  I am also informed that 3.90.3 makes better VBR files, so the change is warranted even if one is not working with such large files (this would explain why 3.90.3 was released after 3.93.1).

There also seems to be a feature of this version that accomplishes my goal without doing the "big file".  It supports a kind of cue sheet that can be used to create a series of seamless mp3s from a CD.

I'll find out soon enough if this works.

Thanks to everyone for your thoughts, ideas, and suggestions.

Edited by mikla on May 02 2003,05:50
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