[FFmpeg-trac] #5189(avformat:closed): Timestamp warnings when concat-ing nut files streamed through fifos

[FFmpeg]

#5189: Timestamp warnings when concat-ing nut files streamed through fifos
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             Reporter:               |                    Owner:
  andrey.utkin                       |                   Status:  closed
                 Type:  defect       |                Component:  avformat
             Priority:  normal       |               Resolution:
              Version:  git-master   |  worksforme
             Keywords:               |               Blocked By:
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
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Changes (by andrey.utkin):

 * status:  new => closed
 * resolution:   => worksforme


Comment:

 This is an isue with concat demuxer - cat->files[1]->start_time stays
 NOPTS when file[0] duration is unknown, which is the case. Later,
 cat->files[1]->start_time is used to calculate `delta`. There's no check
 for start_time == NOPTS, thus delta is invalid.

 Fixing this usecase is possible by constant recalculation of files' known
 duration. This adds overhead for general case. So for now I'll stick with
 adding "duration" directives to concat input file.

 I'm considering submitting a patch adding a warning, stating that duration
 of input file is not known and calculation of delta will be incorrect.
 Also setting start_time to 0 explicitly in this case would decrease
 weirdness.

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Ticket URL: <https://trac.ffmpeg.org/ticket/5189#comment:1>
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