[FFmpeg-devel] Format of decoded text subtitles

Nicolas George nicolas.george at normalesup.org
Wed Aug 1 22:41:16 CEST 2012

Le quintidi 15 thermidor, an CCXX, Clément Bœsch a écrit :
> Are you sure it needs to be nested? The current decoders are transforming

Everything and anything I just wrote is open for discussion, of course.

> nested markup to "flat" one in ASS; I think it's best to keep that logic.
> It will be simpler to convert the decoders at least. And we will limit the
> ASS markup surprises.

IMHO, one of the objectives is that decode+encode for the same codec is
lossless or almost so. I believe that flat -> nested -> flat is easier to
make lossless than nested -> flat -> nested.

> We need to be *very* cautious when messing with the ASS event.  I'd
> suggest you to have a deep look at libass/ass_{parse.c,types.h} before
> planing anything. Think of Karaoke events at least.

I'll have to look at it, clearly.

> Looks sane.

Do you think it can reliably represent the exotic codecs you know of?

> How is that really different from the current state?

Indeed no. It only requires that all styles above the EVENT (or "PACKET")
level are accessible from the AVCodecContext at the beginning and uniquely


  Nicolas George
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