[FFmpeg-trac] #8456(undetermined:closed): Copy codec doubles video stream (was: Copy codec doubles duration of video stream)

FFmpeg trac at avcodec.org
Sun Jan 5 11:04:30 EET 2020

#8456: Copy codec doubles video stream
             Reporter:  MarianD      |                    Owner:
                 Type:  defect       |                   Status:  closed
             Priority:  normal       |                Component:
                                     |  undetermined
              Version:  git-master   |               Resolution:  invalid
             Keywords:               |               Blocked By:
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |

Comment (by mkver):

 The video stream in this file has an edit list that says that the video
 should be displayed twice. So actually looping the video is the correct
 behaviour. But I think the file is actually invalid, as the duration of
 the track in the tkhd and the mdhd box both shows 6s, although it is
 double that after applying the edit list.

 mkvmerge has a workaround for this kind of file (see
 here] and
 here]). I don't have a strong opinion on whether such a workaround should
 be added to the mp4/mov demuxer, but I am leaning to no.

 @balling: Repetition flags in the bitstream only ever say: "Output this
 frame twice", but never "play the whole video twice".

Ticket URL: <https://trac.ffmpeg.org/ticket/8456#comment:5>
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