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Comment by bsimpson | Hacker News Reader

This is excellent.

YUV appears to be a PAL-specific color space. I wonder how off an NTSC Wii would be. Presumably it would have the wrong color space until an equivalent conversion scheme was devised for NTSC.

I was surprised to see regional color spaces leak into the project, but I presume that Nintendo's iOS (the coincidentally-named system this is replacing) could handle that abstraction for game developers.

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Some of this is just really widespread imprecise usage of terms: what really should be called "YCbCr" in digital contexts is frequently called "YUV." So-called "YUV" digital formats for video are really really common, and they're used for both NTSC and PAL. "YUV420," YCbCr using 4:2:0 chroma subsampling so the two color components are half the resolution in each dimension vs. the luma, in particular is super-common.

The Wii seems to actually use "YUV422" internally, so 4:2:2 chroma subsampling, where the chroma is only halved in one dimension. The conversion to analog NTSC or PAL signals happens later in the process. The repository here actually looks like it sets up the Wii's video interface to output NTSC progressive by default, but lets you configure for PAL with a config file.

YUV is a color model, akin to RGB or HSL; it's independent of video formats like NTSC or PAL.

That's true in broad strokes, but looking into it, it turns out NTSC's variant of YUV is called YIQ, and SECAM's variant is called YDbDr. They are however all more or less the same thing, and the digital YUV used by the Wii hardware in this case is presumably independent of the video standard.

Nit: Nintendo's thing is called IOS

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