[FFmpeg-trac] #6826(avformat:new): -copyts does not work with concat demuxer

[FFmpeg]

#6826: -copyts does not work with concat demuxer
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             Reporter:  Sesse     |                     Type:  defect
               Status:  new       |                 Priority:  normal
            Component:  avformat  |                  Version:  git-master
             Keywords:            |               Blocked By:
             Blocking:            |  Reproduced by developer:  0
Analyzed by developer:  0         |
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 Hi,

 I'm having two NUT files that came out of a split; literally, at some
 point, my program just closed the file, opened a new one and continued to
 write packets with no pts gap or similar. I'd like to join them back
 together again. However, evidently I can't; when I join them using the
 concat filter, I get a three-hour gap in the middle. I've tried using
 -copyts, and that works fine if I only have one file the usual way:

 {{{
 > ffmpeg -copyts -i file:record-2017-11-05-13:00:24+0100-f67.nut -c copy
 osipcl2.nut
 [some churn]
 > ffprobe -show_streams ./osipcl2.nut 2>&1 | grep start_pts
 start_pts=1381844448
 start_pts=552732979
 }}}

 However, when using the concat demuxer, it still messes with the pts:

 {{{
 > cat osipcl2.txt
 file 'file:record-2017-11-05-13:00:24+0100-f67.nut'
 file 'file:record-2017-11-05-13:37:23+0100-f59.nut'
 > ffmpeg -copyts -safe 0 -f concat -copyts -i osipcl2.txt -c copy
 osipcl2.nut
 [more churn]
 > ffprobe -show_streams ./osipcl2.nut 2>&1 | grep start_pts
 start_pts=12000
 start_pts=0
 }}}

 I suppose there's some other issue here with the three-hour extra gap, but
 just having it respect -copyts would solve that problem automatically for
 my part. The files should have the same timebase and stream layout and
 everything, so just blindly shoving packets from one to the other ought to
 work.

 The two files are 1,4 GB and 34 MB respectively, so I thought I should't
 attach them, but ask if you need a copy :-)

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Ticket URL: <https://trac.ffmpeg.org/ticket/6826>
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