[FFmpeg-user] YUV 422P Conversion Clipping detection

[tkoole]

I'm trying to detect clipping when converting from YUV422p to RGB24. I've
looked through some of the variables included when calling sws_scale() but
didn't find any flags that stood out so I'm trying to convert manually using
the descriptions on wikipedia. http://en.wikipedia.org/wiki/YCbCr

I've tried several different methods of converting but I don't seem to be
getting the proper rgb values. sws_scale converts the image properly however
when I convert it I get values between 16-20; 

'img' is just a small struct wrapping the frame
'frame' is the AVFrame containing the image

int vc = 0, uc = 0;
for(DWORD i = 0; i < img.width - 1; i += 2) {
		float y1 = img.frame->data[0][i];
		float y2 = img.frame->data[0][i+1];
		float u = img.frame->data[1][vc++];
		float v = img.frame->data[2][uc++];
		
		//int Cr = u;
		//int Cb = v;

		//float r = y1 + 1.402f * (Cr - 128);
		//float g = y1 - 0.344f * (Cb - 128) - 0.714 * (Cr - 128);
		//float b = y1 + 1.772f * (Cb - 128);
		//int r = y1 + Cr + (Cr >> 2) + (Cr >> 3) + (Cr >> 5);
		//int g = y1 - ((Cb >> 2) + (Cb >> 4) + (Cb >> 5)) - ((Cr >> 1) + (Cr >>
3) + (Cr >> 4) + (Cr >> 5));
		//int b = y1 + Cb + (Cb >> 1) + (Cb >> 2) + (Cb >> 6);
		float r = 255.f / 219.f * (y1 - 0.f) + 255.f / 112.f * 0.701f * (u -
128.f);
		float g = 255.f / 219.f * (y1 - 0.f) - 255.f / 112.f * 0.886f * 0.114f /
0.587f * (v - 128.f) - 255.f / 112.f * 0.701f * 0.299f / 0.587f * (u -
128.f);
		float b = 255.f / 219.f * (y1 - 0.f) + 255.f / 112.f * 0.886f * (v -
128.f);
		
		rMax = (r > rMax) ? r : rMax;
		gMax = (g > gMax) ? g : gMax;
		bMax = (b > bMax) ? b : bMax;

		rMin = (r < rMin) ? r : rMin;
		gMin = (g < gMin) ? g : gMin;
		bMin = (b < bMin) ? b : bMin;
		
// ..... repeat for y2

}

Thanks for your time.

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