[FFmpeg-devel] [PATCH]concatdec: measure duration when it is not available

Bodecs Bela bodecsb at vivanet.hu
Tue Mar 1 09:20:57 CET 2016


ping


2016.02.23. 9:21 keltezéssel, Bodecs Bela írta:
> ping
>
> 2016.02.17. 14:13 keltezéssel, Bodecs Bela írta:
>>
>>
>> 2016.02.16. 10:42 keltezéssel, Nicolas George írta:
>>> L'octidi 28 pluviôse, an CCXXIV, Bodecs Bela a écrit :
>>>> Do you have any suggestion for me what to do now?
>>>> Please give me a hint where to find this bug or should I open a 
>>>> trac ticket
>>>> for it?
>>> I already told you: find out exactly WHY the result is different. I 
>>> suggest
>>> you use this kind of test case:
>>>
>>> ffprobe -show_packets -show_streams input.ts
>>> cat input.ts | ffprobe -show_packets -show_streams -
>>>
>>> When we know why, we can discuss how.
>>>
>>> Regards,
>> I have checked the code where and when duration filled and made some 
>> reasoning about it.
>> Duration value for input files has been populated some time after 
>> opening. (estimate_timings function in utils.c) And never again 
>> corrected or called this function..
>> So, if early in processing there is no duration info, it remains empty.
>> When input is not a seekable file but a not-seekable stream, the only 
>> chance to get a duration info  when the stream itself contains info 
>> about this value. (eg. flv metadata, mp4-moov)
>> But mpegts format does not contain this info. So the only moment when 
>> duration calculatable is when we finish the reading. I think 
>> contoniously updating the duration value after each packet would not 
>> be a good idea.
>> (cur_dts is updated is AVStream->info struct)
>>
>> So reading a file via pipe or reading hls stream via http it is 
>> normal that duration value remains empty.
>>
>> thus, I think to handle the cases when duration value is not 
>> populated, this is not a bug fix but a reasonable solution for these 
>> cases.
>>
>> I agree with you that we should not "measure" our-own the pts values 
>> but I could not find any existing/available data member to have this 
>> info.
>>
>> best regars,
>>
>>
>>>
>>>
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>>> ffmpeg-devel at ffmpeg.org
>>> http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
>>
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>
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