YUV422 to RGB (422sp to 420p)

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YUV420 turn RGB888

yuv420 The data storage method of is planar, Is to save in one frame first y component , End of deposit y save u, next v component . And in the yuv420 There is y component widthheight byte,uv Each component is widthheight1/4, The total data in a frame is widthheight3/2（widthheight12/8）. So I thought ,yuv If the component is substituted into the conversion formula ,uv Is the weight less . It's not , Because every four y Components share one u One component v component , But it's not [YiYi+1Yi+2Yi+3] share [Ui],[Vi], Because it's a 22 In the window of Y Components share one uv, therefore [YiYi+1Yi+wYi+w+1], among i It's even .uv Since the components are in the horizontal and vertical directions respectively 2：1 sampling , therefore [U(i/2*w/2+j/2)],V The same goes for components .

#include <iostream>
#include <stdio.h>
#include<fstream>

using namespace std;

bool yuv420ToRgb(char *yuv, int w, int h, char *rgb)
{ 
   
	unsigned char *y = new unsigned char[w*h];
	unsigned char *u = new unsigned char[w*h / 4];
	unsigned char *v = new unsigned char[w*h / 4];

	memcpy(y, yuv, w*h);
	memcpy(u, yuv + w * h, w*h / 4);
	memcpy(v, yuv + w * h * 5 / 4, w*h / 4);

	for (int i = 0; i < h; i++)
	{ 
   
		for (int j = 0; j < w; j++)
		{ 
   
			rgb[i*w*3 + 3*j] = 1.164*(y[i*w+j] - 16) + 1.596*(v[i / 4 * w + j / 2] - 128);//R

			rgb[i*w*3 + 3*j+1] = 1.164*(y[i*w + j] - 16) - 0.392*(u[i / 4*w+j/2] - 128) - 0.813*(v[i / 4 * w + j / 2] - 128);//G

			rgb[i*w*3 + 3*j+2] = 1.164*(y[i*w + j] - 16) + 2.017*(u[i / 4 * w + j / 2] - 128);  //B
		}
	}
	free(y);
	free(u);
	free(v);
	return true;
}


int main(int argc, char* argv[])
{ 
   
	FILE *yuv, *out;	
	int len = 832 * 480 * 3 / 2;
	char  *yuvbuff = ( char *)malloc(len);
	char  *rgbbuff = ( char *)malloc(len*2);
	char  *buff = (char *)malloc(len * 2);
	yuv = fopen("D://movie player//BasketballDrill_832x480_50.yuv", "rb");
	out= fopen("D://movie player//rgb888.txt", "wb+");

	ifstream fl("D://movie player//BasketballDrill_832x480_50.yuv", ios::binary);
	fl.seekg(0, ios::end);
	int size = fl.tellg();
	int inFrameNum = (width*height * 3 / 2);
	int frameNum = size / inFrameNum;

	for (int i = 0; i <frameNum; i++) { 
   
		fread(yuvbuff, 1, width*height * 3/2, yuv);
		yuv420ToRgb(yuvbuff, width, height, rgbbuff);
	    fwrite(rgbbuff, 1, width*height * 3 ,out);
	}
		return 0;
}

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