[FFmpeg-devel] [PATCH 2/2] Adding closed caption decoder

Nicolas George george at nsup.org
Thu Dec 4 12:18:48 CET 2014

Le quartidi 14 frimaire, an CCXXIII, Anshul a écrit :
> It would be valid, c708 is backward compatible as far as
> I have seen while working with ccextractor.
> C708 is made in such a way that people dont have to throw there older TV
> sets or device.
> if any decoder is not able to decode c708 part, even then they can get
> correct subtitle.

So if I understand you correctly, the format could have kept the same name,
just as when Matroska adds a new codec name, and the name is only relevant
as an indication of what a decoder is capable of handling.

> Yes while doing that only I realized,  if we use "i" then cc must be in
> first stream.
> When I had multiple stream(with audio), then I was not able to map subcc
> to my video stream.
> using stream_idx , we are saying that if we can use  out0+subcc and
> out1+subcc.
> "i" logic fails when there is audio in 1st stream, there was no way i 
> could get the subtitle
> if my first stream is not the one where closed caption are present.

I will look more closely into it.

In the meantime, you may want to have a look at this one:


I see quite a few subcc packets, but the decoder does not output anything.
Furthermore, I do not see any ASS styling in the decoder, that would be a
good test case.

More comments to come.


  Nicolas George
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