[FFmpeg-devel] [PATCH 2/3] textdec: Rename all generic parts from srt to text.

Nicolas George nicolas.george at normalesup.org
Thu Aug 2 19:25:18 CEST 2012

Le sextidi 16 thermidor, an CCXX, Clément Bœsch a écrit :
> Oh so another codec to handle that special case? Sounds weird... Does
> these exceptions need so much attention?

I really do not understand what you mean.

> In that case the second solution I propose is more appropriate.


> I was wondering if the decode would do a convert from the AVSubtitle to
> ASS; see below, I'm correcting myself.

Definitely no.

Except, of course, during a transition period, for compatibility.

> OK so based on what you just said, and the initial second suggestion I was
> proposing, maybe we could come with:
> Let's assume the SubRip decoder is fed with the following event:
>     {\an6}<i>Hello <b>World</b></i>
> The decoder would output AVSubtitles (impl. detail: modified to become an
> AST, maybe AVASTSubtitles or whatever) containing an event list such as:
>     [content="{\an6}Hello ", style=ITALIC] --> [content="World", style=BOLD|ITALIC]
> This is then exploitable by the app for one use or another (impl. detail:
> this is what will be injected to libavfilter as well so we might want to
> put that new subtitles struct in lavu).

Until now, ok.

>					  Then assuming this app is a player
> and want to burn/display the subtitle with libass by itself, it would
> encode that AVASTSubtitles to ASS with a avcodec_encode_subtitle2(); then
> AVPacket received can then be directly piped to libass.

It would need to be muxed as well, since the timestamps should be eliminated
from the ASS packets.

Or a helper function, since we will need to implement it anyway for

> Now concerning the escaping, we can have some pre processing in the new
> avcodec_decode_subtitles2(): before calling the demuxer decode function,

s/demuxer/decoder/, I suppose?

> we can escape all the '{' and '}' according to a global option (and the
> codec will need to support the operation: this can't be done that easily
> with MicroDVD which uses { } as well; at first that flag could be set only
> for SubRip and SAMI). Or we can do it after the decode as well.

Definitely not before, for exactly the reason you said, and because we do
not know how the codec handles \. It can be done afterwards, or it can be
done during by a helper function, that does not matter.


  Nicolas George
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