kVToG             137 3rdparty/libwebp/dsp/yuv.h #define kGCst (-kYScale * 16 + kUToG * 128 + kVToG * 128 + YUV_HALF)
kVToG             155 3rdparty/libwebp/dsp/yuv.h   return kYScale * y - kUToG * u - kVToG * v + kGCst;