[FFmpeg-trac] #11462(undetermined:new): Cannot embed .scc file into .mp4 using -c:s copy
FFmpeg
trac at avcodec.org
Mon Feb 10 19:38:07 EET 2025
#11462: Cannot embed .scc file into .mp4 using -c:s copy
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Reporter: Zach | Owner: (none)
Type: enhancement | 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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Comment (by softworkz):
Replying to [comment:17 Zach]:
> I am ok with considering another separate command line tool for this,
but libcaption as currently appears is more of a library than a command
line utility as their releases are source code only.
There are a number of cli tools when compiling, but I'm sure you can find
a tool which does exactly that part. And this is getting to the point:
I understand that you are trying to isolate and separate your requirements
into smaller parts, trying to resolve them individually.
This is often a good pattern for solving problems, but in this case -
knowing about your full set of requirements - the solutions for the
individual aspects do not sum up to that kind of solution you are looking
for.
> Would it make more sense to have the captions be merged in a filter in
the uncompressed domain?
Yes. This is the only way that will gives you full control. Working at the
level of SCC data only is limiting your abilities in many different ways:
- like you said yourself on the ML: The CC data you are getting and need
to work with is "a mess". That's something you can't remedy when working
only at the CC level.
- You are unable to convert from any non-CC format to CC captions
- You would be forever limited to work only with the CC data you get as
input - and for just that, "bringing existing CC data into a video
stream", you'll find a tool which is more suitable for this than ffmpeg
- Even if somebody would implemented such bitstream filters (note that
it's plural, it requires different implementations by coded), it would not
be a solution that could be combined with other ffmpeg functionality in a
useful way
The reason why I appear to have a somewhat different view than the others
is that in my view and thinking, the new subtitle filtering capabilites
are already included, and the others haven't pictured that yet.
> This risks loosing visual quality for compressed files
Yes, but don't you need to re-encode the video anyway? Or will it be re-
encoded at a later stage? In the latter case, you could transcode to a
very high quality (for local intermediate processing) to minimze quality
loss.
This discussion made me wonder about whether it might be feasible to have
decoders produce AVFrames where the side data is parsed out but the video
data remains undecoded. This might also help for certain ffprobe scenarios
(Marth64: you know what I'm up to.. :-)
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Ticket URL: <https://trac.ffmpeg.org/ticket/11462#comment:29>
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