[FFmpeg-devel] Subtitle filters in libavfilter

[Chris Burel]

My original post was this one, and it gives some of the issues with doing
the rendering in the xsub encoder or ass decoder:
http://ffmpeg.org/pipermail/ffmpeg-devel/2011-May/112170.html

At the time, it was suggested to add subtitle support to libavfilter, and
that seemed like the cleanest approach to me.  Then when I saw the ass
video filter had already been implemented, it seems like most of the code
is already in place.  All that would be necessary is to split up the filter
into two separate ones.


2013/1/29 Marcus Johnson <bumblebritches57 at gmail.com>

> Blu-rays use PGS subs, which are bmps why can't you render directly?
>
>
> On Tue, Jan 29, 2013 at 4:42 PM, Chris Burel <chrisburel at gmail.com> wrote:
>
> > Hi,
> > A while ago, I wrote about trying to add support for rendering text-based
> > subtitles.  What I'm trying to achieve is to support transcoding .ass
> > subtitles to xsub, to stream to the PS3.
> >
> > I saw recently that some new video filters had been added, one called
> "ass"
> > and one called "subtitle", for hard-coding the subtitles into the video
> > stream.  These filters were implemented as video filters.  I started
> > looking at the code, and it seems like most of the code could be reused
> if
> > there were a bit more division of labor.  I'd like to see one filter for
> > rendering text subtitles to images, that would output a subtitle stream,
> > and a separate filter that would hard-code those subtitles on top of a
> > video stream.  That way, all the code for rendering the subtitles could
> be
> > used for transcoding them to any image-based subtitle format.
> >
> > I started looking at adding subtitle support to libavfilter, but I got
> > bogged down in bits that I don't see how they apply to a subtitle stream,
> > like the query_formats() function.  Is there someone that could help me
> > write a null subtitle filter, to see what all the necessary parts are?
> >
> > Thanks,
> > Chris
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