[x264-devel] I444 support

[Loren Merritt]

On Tue, 27 Nov 2007, Loïc Le Loarer wrote:

> The new 4:4:4 profile has a mode which uses 3 monochrome planes, one of
> each color component (either RGB or YUV), encoded independently, to
> support 4:4:4. It shouldn't be really difficult in add support for this
> mode in x264 (or any other encoder) as it is the matter to first add
> monochrome support (remove chroma compression) and them consider each
> picture as 3 monochrome planes instead of only one.

It's not that simple. x264 treats luma very differently than chroma, due 
to the different motion compensation method. So you'd have to either make 
sweeping changes to buffer management, or invoke 3 separate instances of 
the whole monochrome encoder. 3 encoders would screw with ratecontrol, 
though that's not relevent to lossless mode.

--Loren Merritt