[FFmpeg-devel] Captions SCC

[FFmpeg-devel] Captions SCC

[Devlist Archive]

Greetings,

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"


https://drive.google.com/drive/folders/13NXvUgE1EIyLR4WBw30l4NVtS5w33EM7?usp=sharing

The file outputs are included in that drive folder.  Please don't
distribute the files online, but you can use them for testing.  The folder
will go away when the job is complete.  I have requested sample files for
distribution from the content provider, but haven't received those yet.

The objective is to fix the character duplication and data spill out that
is happening during extraction and embedding of scc files for these
resolutions.  I will try to get some 1080i samples also, but don't have
those available in source file form at the moment.  There will be other
captions related projects available once this one is complete.

Thanks,

Zach Swena
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Re: [FFmpeg-devel] Captions SCC

[Jack Lau]

> 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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