[FFmpeg-trac] #11105(undetermined:new): webvtt codec not seeking properly with output seeking

[FFmpeg]

#11105: webvtt codec not seeking properly with output seeking
-------------------------------------+-------------------------------------
             Reporter:  Tristan      |                     Type:  defect
  Matthews                           |
               Status:  new          |                 Priority:  normal
            Component:               |                  Version:  git-
  undetermined                       |  master
             Keywords:  webvtt       |               Blocked By:
  caption seeking                    |
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
-------------------------------------+-------------------------------------
 Summary of the bug:

 When trimming and muxing a video with accompanying VTT file (using output
 seeking as per https://trac.ffmpeg.org/wiki/Seeking#Output), if I specify
 `-c:s webvtt`the subtitles are not present as expected in the output.

 However, if I use `-c:s copy` instead, the subtitles are present and line
 up as expected.

 How to reproduce:

 Download https://people.videolan.org/~tmatth/samples/counting.mp4 and
 https://people.videolan.org/~tmatth/samples/counting.vtt

 and trim and mux them with:
 {{{
 % ffmpeg -i counting.mp4 -i counting.vtt -shortest -c:v copy -c:s webvtt
 -ss 20s trimmed.mkv
 }}}


 To see the working/expected version, do:
 {{{
 % ffmpeg -i counting.mp4 -i counting.vtt -shortest -c:v copy -c:s copy -ss
 20s trimmed.mkv
 }}}

 It's possible this should be filed as an "enhancement".
-- 
Ticket URL: <https://trac.ffmpeg.org/ticket/11105>
FFmpeg <https://ffmpeg.org>
FFmpeg issue tracker