[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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Re: [FFmpeg-devel] Captions SCC

[Devlist Archive]

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.
> _______________________________________________
> ffmpeg-devel mailing list
> ffmpeg-devel@ffmpeg.org
> https://ffmpeg.org/mailman/listinfo/ffmpeg-devel
>
> To unsubscribe, visit link above, or email
> ffmpeg-devel-request@ffmpeg.org with subject "unsubscribe".
>
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Re: [FFmpeg-devel] Captions SCC

[Soft Works]

> -----Original Message-----
> From: ffmpeg-devel <ffmpeg-devel-bounces@ffmpeg.org> On Behalf Of
> Devlist Archive
> Sent: Friday, February 7, 2025 6:13 AM
> To: FFmpeg development discussions and patches <ffmpeg-
> devel@ffmpeg.org>
> Subject: Re: [FFmpeg-devel] Captions SCC
> 
> 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.
> > _______________________________________________
> > ffmpeg-devel mailing list
> > ffmpeg-devel@ffmpeg.org
> > https://ffmpeg.org/mailman/listinfo/ffmpeg-devel

> 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


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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Re: [FFmpeg-devel] Captions SCC

[Jack Lau]

> 
> 
> 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
> 


Hi softworkz,

Sorry about that, The response is indeed from AI. I thought this question was enough for AI to answer, I will pay attention to it next time.

Thank you for pointing it out.

Jack
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Re: [FFmpeg-devel] Captions SCC

[Soft Works]

> -----Original Message-----
> From: ffmpeg-devel <ffmpeg-devel-bounces@ffmpeg.org> On Behalf Of
> Jack Lau
> Sent: Friday, February 7, 2025 8:58 AM
> To: FFmpeg development discussions and patches <ffmpeg-
> devel@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
> >
> 
> 
> Hi softworkz,
> 
> Sorry about that, The response is indeed from AI. I thought this
> question was enough for AI to answer, I will pay attention to it next
> time.
> 
> Thank you for pointing it out.
> 
> Jack


Hi Jack,

"paying attention next time"?  That's not the right answer.

Please make sure that there won't be a next time.

The big evil with LLVMs is not the fact they are making mistakes but the extreme level of confidence at which they are presenting these mistakes - like no human would do.
That's why we tend to fall so easily into taking their trash for granted.

sw


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Re: [FFmpeg-devel] Captions SCC

[Jack Lau]

> 
> Hi Jack,
> 
> "paying attention next time"?  That's not the right answer.
> 
> Please make sure that there won't be a next time.
> 
> The big evil with LLVMs is not the fact they are making mistakes but the extreme level of confidence at which they are presenting these mistakes - like no human would do.
> That's why we tend to fall so easily into taking their trash for granted.
> 
> sw
> 
> 

Hi softworkz,

Thanks for your reply and reminder, I’ll ensure there won't be a next time.

Jack

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Re: [FFmpeg-devel] Captions SCC

[Soft Works]

> -----Original Message-----
> From: ffmpeg-devel <ffmpeg-devel-bounces@ffmpeg.org> On Behalf Of
> Jack Lau
> Sent: Friday, February 7, 2025 9:26 AM
> To: FFmpeg development discussions and patches <ffmpeg-
> devel@ffmpeg.org>
> Subject: Re: [FFmpeg-devel] Captions SCC
> 
> 
> >
> > Hi Jack,
> >
> > "paying attention next time"?  That's not the right answer.
> >
> > Please make sure that there won't be a next time.
> >
> > The big evil with LLVMs is not the fact they are making mistakes
> but the extreme level of confidence at which they are presenting
> these mistakes - like no human would do.
> > That's why we tend to fall so easily into taking their trash for
> granted.
> >
> > sw
> >
> >
> 
> Hi softworkz,
> 
> Thanks for your reply and reminder, I’ll ensure there won't be a next
> time.
> 
> Jack


Hi Jack,

thanks for your reply and understanding. I wanted to note that it's not about wrong answers in general. 
An answer from yourself that starts with "I think" or similar is very welcome, even when it might be wrong. :-)

sw




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Re: [FFmpeg-devel] Captions SCC

[Jack Lau]

Hi softworkz,

Thank you very much for your patient reply and kind suggestions. I am new to the FFmpeg devel mailing list, and English is not my native language, so there is still a lot for me to learn.

May I ask a question? How long does it usually take for a patch to be reviewed? A few days ago, I submitted a patch titled "[PATCH] examples/transcoding: Fix time_base handling," but it seems that no one has reviewed it yet. I understand everyone is busy, but I was wondering if there has been any feedback or if there are any concerns regarding the patch.

Jack

> 
> Hi Jack,
> 
> thanks for your reply and understanding. I wanted to note that it's not about wrong answers in general. 
> An answer from yourself that starts with "I think" or similar is very welcome, even when it might be wrong. :-)
> 
> sw
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