I was doing some research into the YIQ color space for composite/S-Video reasons, and I stumbled on this:
The original color space used for encoding NTSC video in 1953, which was very similar to YUV. Only a small number of TV sets that decoded YIQ were ever manufactured, and it became obsolete. All NTSC encoding today is YUV. See YUV.
So from what this is saying is CRT’s didn’t use a YIQ color space it used a YUV color space.
Wouldn’t this mean the composite and S-Video shaders should be using RGB/YUV/RGB instead of RGB/YIQ/RGB. (To be more accurate.)