Overlay functions are being replaced by YUV textures. If the driver doesn't support YUV textures, they can be emulated by backing the texture with an RGB texture and using the software conversion routines. Note that it doesn't make sense to lock a portion of a YV12 texture, since you'd need to return three pixel pointers and pitch values instead of the one that's available through the API. I'm guessing that's one of the reasons DirectX 9 doesn't support this format at all.

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