[FFmpeg-devel] [RFC] Implementation of closed caption support

[Reimar Döffinger]

On Mon, Aug 04, 2014 at 08:04:39PM +0100, Kieran Kunhya wrote:
> > And as far as I can tell if you want to remux
> > but with separate subtitle stream that would even mean that you have to
> > re-encode the video for no good reason.
> 
> You can just swap out the caption data. It's guaranteed to be CBR anyway.

Uh, no.
The point is to get the CC data out you need to decode.
Now that you have the video decoded, if you want to mux it you have
to encode it again.
Though maybe it's possible to somehow use the same input stream twice as
input in FFmpeg and copy it once (for muxing) and decode it once (to get
the CC data).