[FFmpeg-devel] [RFC] Talk about subtitles

Stefano Sabatini stefasab at gmail.com
Wed Nov 23 01:16:56 CET 2011

On date Tuesday 2011-11-22 19:56:41 +0100, Clément Bœsch encoded:
> Hi everyone,
> [TL;DR: I want to improve/rewrite a real subtitles support in FFmpeg and need
> some hints.]
> Today again someone asked how to burn subtitles in a video. This is a recurrent
> question which I think need to be solved now: some people still stick to the
> unmaintained mencoder, try some pipes with MPlayer, or some lost code in
> mplayer2, etc. And still nothing user friendly for this. Considering this, I
> really wish to improve the situation with FFmpeg.
> This is all I can think about ATM. So if we want to support this properly, I can
> only think of this: libavsubtitles (with a dependency to libass to render a lot
> of crazy markup in subtitles).

Or in alternative maybe convince the libass author to join and make
libass depend on this new lib ;-). On the other hand I don't think
this would be simple, and designing a generic enough
subtitling/texting rendering layer is going to be a challenge.  But I
suppose that a dependency on libfreetype and maybe fontconfig would be

> This library will be used to demux/decode/etc (for conversion purpose too) and
> render the subtitles. And more importantly, we would be able to use it to burn
> them through the libavfilter with something like vf_subtitles.

> There is ATM a pending patch (vf_ass) that can workaround the situation for most
> of the people: a lot of software allow the convert from srt to ass, so it won't
> be needed to duplicate the srt to ass convert code yet another time for the
> filter. Users will be satisfied enough for a while I think with a simple ASS
> burning filter. It will give us some time to think about a proper way to write
> and integrate libavsubtitles. 

Ah my unfinished works!, wait up to this weekend and if I don't come
up with nothing new feel free to pick up the filter and work on it,
and to relicense it to LGPL if it suits you better.
FFmpeg = Formidable and Fascinating Mythic Perennial Ecstatic Guru

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