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

Carl Eugen Hoyos cehoyos at ag.or.at
Sun Apr 17 21:07:55 CEST 2016


On Sunday 17 April 2016 08:41:32 pm Jan Ekstrom wrote:
> On Sun, Apr 17, 2016 at 9:21 PM, Reimar Döffinger
>
> <Reimar.Doeffinger at gmx.de> wrote:
> > In particular, I have an uncomfortable suspicion that
> > PGS might be designed to match the movie's colour space,
> > in which case neither variant would give correct results
> > but instead it would have to depend on what format the
> > corresponding video track uses (and it probably would
> > be more than just the 255/224 factor that would differ).
>
> Yes, the YCbCr values in palettes are matched accordingly against the
> video stream. As per the specification:
> "Y, Cr and Cb shall have the same color matrix as the associated HDMV
> Video stream: 525-60/625-50 (Rec.601); 1080i, 720p (ITU-709)"
>
> Otherwise the specification notes that valid values in palettes are:
> -Y: 16-235
> -Cr: 16-240
> -Cb: 16-240
> -Transparency: 0-255, where a value of ‘255’ indicates full opacity
> and ‘0’ indicates full transparency.
> (Each Palette entry shall have a default transparency value of 0; the
> default values of Y, Cr and Cb are undefined.)
>
>
> Best regards,
> Jan Ekström
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