[FFmpeg-devel] [PATCH] mkv MatroskaBlock.duration not initialized for SimpleBlock

John Stebbins stebbins at jetheaddev.com
Fri Mar 18 04:14:35 CET 2011

On 03/16/2011 03:54 PM, Aurelien Jacobs wrote:
> On Wed, Mar 09, 2011 at 06:52:26PM -0800, John Stebbins wrote:
>> When a normal Block is parsed, duration is initialized to
>> AV_NOPTS_VALUE.  If it is not changed, then the track's default
>> duration is used.  But for SimpleBlock, duration is initialized to 0
>> instead of AV_NOPTS_VALUE.  This is due to the difference in how
>> EBML_NEST vs EBML_PASS are processed.  Setting duration to 0 leads
>> eventually to estimating the frame duration in util.c.
> Indeed. Thanks for the good analysis.
> I've just fixed it in a slightly nicer way.
>>   For the
>> sample I am testing (DTS-HD MA track in mkv generated by MakeMKV),
>> this estimate is based on frame size and bitrate which is wildly
>> inaccurate. End result is pts values that jump all over the place
>> and sometimes go backwards.
> Could you please check if my fix works fine for your sample ?
> Aurel

I should have time to test the latest code tomorrow.  Did your patch 
make it to a mailing list somewhere?  I can't find it in all the 
confusion with the splits and all.  I would like to look it over to see 
how you solved the problem.


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