Re: [FFmpeg-devel] Captions SCC

[Devlist Archive <devlist@rlb.org>]

Hi Jack,

Thanks for the suggestions.  Could you please tell me where I can get a
build of ffmpeg that will work with the -c:s scc command?  That encoder
doesn't seem to be in the release version I am working with.

It is slightly unclear to me how your suggestion for the extract command
suggestion should be implemented.  All of my media files I am working with
now are the same frame rate, but forcing a frame rate prior to embedding is
probably a good idea.  I had assumed there were still bugs in the code for
this, but it would be nice if extraction/embedding could work without
having to  change more.

Zach

On Thu, Feb 6, 2025 at 4:57 AM Jack Lau <jacklau1222gm@gmail.com> wrote:

>
>
> > I have been absent from the list for a few years, so I would appreciate
> it
> > if someone could catch me up a bit.  I am needing to extract and embed
> scc
> > files with 608 captions.  I am pleased to see that transcoding without
> > frame rate changes now preserves 608 intact, and there appear to be
> > extraction and embed functions but they do seem to have bugs for my files
> > at 1080p2997.  Are there any developers willing to take on a paid project
> > to fix whatever is the issue?  Here are the commands I am working with.
> >
> > Embed:
> > "C:\FFmpeg\ffmpeg7.1_2024-12-14\ffmpeg.exe" -i
> > "C:\Users\Captions\AIM-2301_premiereDF.mp4" -i
> > "C:\Captions\AIM-2301_premiereDF.mp4.scc" -map 0:v -map 0:a -map 1 -c:v
> > copy -c:a copy -c:s mov_text -metadata:s:s:0 language=eng
> > "C:\Captions\AIM-2301_premiereDFcopy.mp4"
> >
> > Extract:
> > "C:\FFmpeg\ffmpeg7.1_2024-12-14\ffmpeg.exe" -f lavfi -i
> >
> "movie=\'C:\\Captions\\AIM-2301_premiereDF_ffmpegEmbedscc.mp4\'"[out+subcc]
> > -map 0:1 -c:s copy "C:\Captions\AIM-2301_premiereDF_ffmpegEmbedscc.scc”
> >
>
>
> Hi,
>
> I’ve reviewed the issue with embedding and extracting 608 SCC captions at
> 1080p2997 resolution and identified a few areas that might help resolve the
> character duplication and data spill. Here's a summary of my findings:
>
> The current command uses -c:s mov_text, but SCC files may work better with
> -c:s scc to preserve the format correctly.
> The current command uses a filtergraph that might not map correctly for
> SCC extraction. Instead, try simplifying the extraction command: -map 0:s:0
> -c:s copy
> Frame Rate Issues: Ensure the video frame rate and the SCC file frame rate
> match. You might want to force a specific frame rate (e.g., -r 29.97).
>
> Let me know if you have further questions.
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