[FFmpeg-devel] [PATCH]lavc/pgssubdec: Fix palette colourspace

[Reimar Döffinger]

On Sun, Apr 17, 2016 at 09:49:58PM +0300, Jan Ekstrom wrote:
> On Sun, Apr 17, 2016 at 9:44 PM, wm4 <nfxjfg at googlemail.com> wrote:
> >
> > Ah that's funny. This indeed ruins everything. It looks like subtitle
> > decoders should simply output YUV, and until we can fix it, a private
> > option could change between the colorspaces?
> 
> Well, the colorimetry is at least specified as per the resolution, and
> while I haven't confirmed it I would guess you could decide things by
> the size of the "canvas", since it seems like SD content has been
> deemed Rec.601, while HD content has been deemed Rec.709).
> 
> Of course, I do agree that enabling YCbCr output could be one way of
> getting through this for some users of the API.

One suspicion: Does the spec say anything on alpha blending?
Because this close relation with video colour space sounds
a lot like alpha-blending might have been intended to be
done in YUV space. Which would potentially give quite different
results from doing it in RGB.