Soft Works said... "the CC data needs to get into the video frames - so that it 
exists as input to the video encoder.
For the same reason, it is also not possible to add CCs at the muxer level. It 
always requires video encoding because the data needs to get into the video 
stream itself, so there's no way to get data from an SCC file into a video 
stream currently."

You're confusing subtitles with closed captions. Subtitles are text that is 
composited into the video. CEA-708 closed captions are carried as metadata in 
SEI NAL units, muxed into the elementary video stream.

Tom

On 2/6/25, 11:48 PM, "ffmpeg-devel on behalf of Soft Works" 
<ffmpeg-devel-boun...@ffmpeg.org <mailto:ffmpeg-devel-boun...@ffmpeg.org> on 
behalf of softworkz-at-hotmail....@ffmpeg.org 
<mailto:softworkz-at-hotmail....@ffmpeg.org>> wrote:


> -----Original Message-----
> From: ffmpeg-devel <ffmpeg-devel-boun...@ffmpeg.org 
> <mailto:ffmpeg-devel-boun...@ffmpeg.org>> On Behalf Of
> Devlist Archive
> Sent: Friday, February 7, 2025 6:13 AM
> To: FFmpeg development discussions and patches <ffmpeg-
> de...@ffmpeg.org <mailto:de...@ffmpeg.org>>
> Subject: Re: [FFmpeg-devel] Captions SCC
> 
Hi Zack,
that message from "Jack" had confused me for a moment, but on re-reading it 
appears to be an AI response.
The content is total nonsense. There is no "SCC" encoder in ffmpeg, and if 
there was one, it wouldn't help much because the CC data needs to get into the 
video frames - so that it exists as input to the video encoder.
For the same reason, it is also not possible to add CCs at the muxer level. It 
always requires video encoding because the data needs to get into the video 
stream itself, so there's no way to get data from an SCC file into a video 
stream currently.

The only way in the ffmpeg architecture to get CC data encoded would be at the 
filtering level. The Subtitle Filtering patchset that I have submitted a while 
ago has a "splitcc" filter which has video as input and a video plus a subtitle 
pin/pad at the output side.
What would be needed is a reverse pendant like a "mergecc" filter with video 
and subtitles input - plus a CEA-608/708 encoder.

softworkz

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