[FFmpeg-trac] #9804(undetermined:new): MP4 captions break when extracted to scc

[FFmpeg]

#9804: MP4 captions break when extracted to scc
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             Reporter:  Zach         |                     Type:  defect
               Status:  new          |                 Priority:  important
            Component:               |                  Version:  git-
  undetermined                       |  master
             Keywords:               |               Blocked By:
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
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 Summary of the bug:

 I have mp4 files coming in from outside content providers that contain
 user space 608 and 708 captions.  When trying to extract an scc file, some
 of the captions data is lost, resulting in mispellings in the resulting
 captions file when opened in Adobe Premiere 2022.  SRT extraction and
 transcode to mpegts transport stream or mxf files also breaks captions in
 different ways.

 How to reproduce:
 {{{
 % ffmpeg -f lavfi -i "movie=\'D:\\IIW242.mp4\'"[out+subcc] -map 0:1 -c:s
 copy "D:\IIW242.scc"
 ffmpeg version 2022-06-06-git-73302aa193-full_build-www.gyan.dev
 }}}
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Ticket URL: <https://trac.ffmpeg.org/ticket/9804>
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