[FFmpeg-devel] Subtitle filters in libavfilter

[Marcus Johnson]

I'm not the boss or anything, just a commentor waiting for a response, and
tried helping out another commentor. :c


On Tue, Jan 29, 2013 at 5:17 PM, Chris Burel <chrisburel at gmail.com> wrote:

> 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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> > >
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