[FFmpeg-devel] [RFC] Google Summer of Code 2013

Kieran Kunhya kierank at ob-encoder.com
Thu Mar 7 11:42:01 CET 2013

On Thu, Mar 7, 2013 at 9:23 AM, Reimar Döffinger
<Reimar.Doeffinger at gmx.de> wrote:
> So in other words it's completely useless because it won't actually work?
> Splitting it at the decoder sure is a possibility of you can't be bothered to come up with a proper solution that actually is convenient and fits into the API.
> Of course it means only programs that add special code for our will support it.
> And WTV will end up giving you the same subtitle stream twice.

I don't see at all how you are going to get captioning in the current
API. It is impossible without horrible hacks (calling the cc decoder
from mpeg-2/h264?). I have no idea why WTV sees the need to make an
additional stream - seems odd to me unless they want to avoid the same
issues as FFmpeg. VLC adds special code for captioning because you
have no choice because it's impossible to do in the lavf/lavc
paradigm. Outputting captions frame accurately is a step forward

>>Teletext is a lot of work; one might be able to get just the subtitles
>>part working I guess.
> Uh, what part of it is a lot of work?
> The format is not that complex, less than ATSC captions.
> Selecting a page could be done as a decoder option at first.
> Supporting analog teletext could also be separate.

Oh you just want teletext subtitling - that'll fit in the current API
I suppose but the pages themselves won't.

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