Re: [gst-devel] [cairo] Planar YUV support

[Ville S. <sy...@sc...>]

On Tue, Mar 09, 2010 at 10:36:13AM -0800, Michael Smith wrote:
> On Tue, Mar 9, 2010 at 9:00 AM, Arjen Nienhuis <a.g...@gm...> wrote:
> > Hi,
> >
> > Your works looks really useful! Did you make read/write support for
> > all these formats? That means it can speedup things like JPEG
> > enc/decoding right?
> >
> > Minor nitpick:
> >
> > I think pixman_color_space_t is not the right name. It's ambiguous
> > because color space can also mean sRGB vs AdobeRGB. What about
> > 'encoding'?
> 
> pixel_format would probably be a better name if it's _only_ intended
> to encode the pixel format. I think Benjamin's intent, though, was to
> encode a pair of "pixel format, colour space" in a single value.
> That's why his suggestion has YCBCR_SD and YCBCR_HD - these have the
> same pixel formats, but imply a different colour space.

It's also a bit unclear what range these use. I'm assuming the
idea was that YCBCR_{SD,HD} use the 16-235 range and YCBCR_JPEG the
0-255 range.

One thing that's completely missing is the chroma siting. For 420P
there are three different variations in use. Four if you count the
MPEG2 interlaced version as a separate thing.

I don't know how fancy people want to go with this stuff but ffmpeg
and microsoft have some relevant stuff here:
http://git.ffmpeg.org/?p=ffmpeg;a=blob;f=libavcodec/avcodec.h
http://msdn.microsoft.com/en-us/library/bb970322(VS.85).aspx

-- 
Ville Syrjälä
sy...@sc...
http://www.sci.fi/~syrjala/