[FFmpeg-trac] #6421(undetermined:open): PTS incorrectly fixed up to be negative

FFmpeg trac at avcodec.org
Fri Jun 2 20:16:28 EEST 2017

#6421: PTS incorrectly fixed up to be negative
             Reporter:  sandersd     |                    Owner:  isasi
                 Type:  defect       |                   Status:  open
             Priority:  important    |                Component:
              Version:  git-master   |  undetermined
             Keywords:  mov h264     |               Resolution:
  edts regression                    |               Blocked By:
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
Changes (by isasi):

 * owner:   => isasi
 * status:  new => open


 This is a bug in the edit list fix index code. This line
 , causes the PTS to be negative. The intention of the line is to make the
 first pts to be zero. But the problem here is that the first packet in the
 decoding order is not the first packet in the presentation order, and in
 that line we are subtracting by the timestamp of the first packet in
 decoding order. What we need to do is find the first packet in the
 presentation order and its resulting PTS after edit list is applied, and
 then offset all the timestamps to make that PTS zero. I am working on that

 You can do -advanced_editlist=0 to disable the fix index feature, but keep
 in mind that without that feature you will have AVSync issues anyway,
 because the timestamps are not adjusted properly according to the edit

Ticket URL: <https://trac.ffmpeg.org/ticket/6421#comment:5>
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