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

[FFmpeg]

#9804: MP4 captions break when extracted to scc
-------------------------------------+-------------------------------------
             Reporter:  Zach         |                    Owner:  (none)
                 Type:  defect       |                   Status:  new
             Priority:  important    |                Component:
                                     |  undetermined
              Version:  git-master   |               Resolution:
             Keywords:               |               Blocked By:
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
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Description changed by Zach:

Old description:

> 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
> }}}

New description:

 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
 }}}

 Link to sample file:
 https://drive.google.com/file/d/1zdX-Vw3iU37xWR2SPRwvonMhoT1gPEUz/

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Ticket URL: <https://trac.ffmpeg.org/ticket/9804#comment:1>
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