[FFmpeg-devel] [PATCH]concatdec: measure duration when it is not available
bodecsb at vivanet.hu
Tue Mar 1 09:20:57 CET 2016
2016.02.23. 9:21 keltezéssel, Bodecs Bela írta:
> 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
>>> 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.
>> 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
>> 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
>> best regars,
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