[FFmpeg-devel] [PATCH] Lost VBR header

Michael Niedermayer michaelni at gmx.at
Sat May 7 04:08:05 CEST 2011

On Fri, May 06, 2011 at 08:53:19PM +0200, Peter Belkner wrote:
> Ping.
> On 29.04.2011 21:08, Peter Belkner wrote:
>> Hi,
>> On 28.04.2011 21:43, Michael Niedermayer wrote:
>>> This patch results in differnt output when the resulting mp3 is decoded
>>> also there are error messages and 3456 samples (6*576) missing at the
>>> start
>> Unfortunately I'm not able to exactly reproduce this error. In some  
>> cases I found some frame headers corrupted.
>> I changed the following:
>>    * Dynamic bitrate index determination to really make sure that the
>>      TOC fits into the XING frame.
>>    * In mp3_write_trailer() changed the order of writing ID3v1 and
>>      fixing the XING header. (Fixing the XING header is now the final
>>      operation. This makes the corrupted frame error vanishing in my
>>      tests. Is there someting I'm missing with AVIO?)
>> In order to avoid overflow in TOC statistics (wrapping to negative  
>> values):
>>    * Diveded the bitrate by 1000.
>>    * Changed the statistics data types from "int" to "uint64_t".
>> Please find a revised patch below.
>> With the new patch I could not find any difference the following way:
>>    unpatched/ffmpeg -i a.mp3 -acodec copy -y b.mp3
>>    unpatched/ffmpeg -i b.mp3 -y b.wav
>>    patched/ffmpeg -i a.mp3 -acodec copy -y c.mp3
>>    patched/ffmpeg -i c.mp3 -y c.wav
>>    diff --binary b.wav c.wav
>> Could you please share the test case (MP3) in case the error is not  
>> vanishing in your environment?
>> Peter
> Is there any chance to get this into FFmpeg?
> Please let me know how I can contribute.
> Thank you for your effort.

Sorry for the delay, i had some changes on top of your last patch
that i needed to rebase to the new, test, check, update ...

All should be commited now, thanks for the patch
and please review my changes that i did on top of your code (more eyes
reveiwing cant hurt)

Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Let us carefully observe those good qualities wherein our enemies excel us
and endeavor to excel them, by avoiding what is faulty, and imitating what
is excellent in them. -- Plutarch
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