[FFmpeg-devel] [PATCH] H264 parser fix

John Stebbins stebbins
Wed Oct 6 19:32:17 CEST 2010

 On 09/28/2010 11:46 AM, John Stebbins wrote:
>  On 09/28/2010 11:20 AM, Michael Niedermayer wrote:
>> On Tue, Sep 28, 2010 at 09:41:03AM -0700, John Stebbins wrote:
>> [...]
>>>> also the factorization should be a seperate patch
>>>> [...]
>>> Any movement on this issue? Still seeing it in svn 25249.  Avatar BD m2ts is a good example of the problem.
>> A variant of this patch has been commited.
>> Is there an issue that is fixed by a prior patch of this thread? 
> Sorry, I didn't test the prior patch.  I assumed it hadn't been committed since I was seeing what appeared to be the
> same problem. Perhaps it's not the same issue.  I do not see these errors with an earlier version of ffmpeg, svn 22950
> which is about 5 months old.
> If you would like, I can back out to a version prior to the variant that was committed and try the prior patch.  Can you
> tell me at what revision that was committed?
I did some more investigation of this and found the source of the problem.  The time_offset_length from hrd_parameters
is not being set to the correct default value when hrd_parameters are not present.  According to the specification:

"When the time_offset_length syntax element is not present, it shall be inferred to be equal to 24."

The proper number of bits are not being read in decode_picture_timing() in the SEI.  Since it is now out of sync with
the bitstream, it starts misinterpreting the remaining data.

Patch attached.

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