Support libx264rgb

[markg85]

(copied from loki-47-6F-64/sunshine#364 As that seems to be a dead project, might as well request it here instead)

Hi,

In the case of desktop streaming you likely always lose some color data. Even if you're using yuv444, you still lose some.

To quote the ffmpeg docs: The libx264rgb encoder is the same as libx264, except it accepts packed RGB pixel formats as input instead of YUV.

I tried this in some other remote desktop tool to see how good it looks. It in fact looks undistinguishable! No more greenish glow around sharp thin edges (think fonts, browsing). Granted, you only really notice this in desktop streaming. With games/video you either don't notice it or it's so little that it doesn't bother you. This does come at a cost though. You transmit more data so you obviously have a little higher bandwidth usage. But you get a pixel perfect result. Tradeoffs :)

Best regards,
Mark