c语言实现.yuv文件转换为.rgb文件

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一、实验目的

将yuv文件转换为rgb文件

二、实验原理

1.YUV与RGB空间的相互转换

由电视原理可知，亮度和色差信号的构成如下：
Y＝0.2990R+0.5870G+0.1140B
R-Y＝0.7010R-0.5870G-0.1140B
B-Y＝-0.2990R-0.5870G+0.8860B
为了使色差信号的动态范围控制在0.5之间，需要进行归一化，对色差信号引入压缩
系数。归一化后的色差信号为：
U＝-0.1684R-0.3316G+0.5B
V＝0.5R-0.4187G-0.0813B

2.码电平分配及数字表达式

⚫ 亮电平信号量化后码电平分配
在对分量信号进行8比特均匀量化时，共分为256个等间隔的量化级。为了防止信号
变动造成过载，在256级上端留20级，下端留16级作为信号超越动态范围的保护带。
⚫ 色差信号量化后码电平分配
色差信号经过归一化处理后，动态范围为-0.5－0.5，让色差零电平对应码电平128，
色差信号总共占225个量化级。在256级上端留15级，下端留16级作为信号超越动态范围
的保护带。

3.色度格式

4:2:0格式是指色差信号U，V的取样频率为亮度信号取样频率的四分之一，在水平方
向和垂直方向上的取样点数均为Y的一半。

三、实验步骤

1.yuv2rgb.h

#pragma once
int YUV2RGB(int x_dim, int y_dim, void* bmp, void* y_out, void* u_out, void* v_out, int flip);
void InitLookupTable();

2.main.cpp

（1）引入库与重新定义

#include <stdio.h>
#include <stdlib.h>
#include <malloc.h>
#include "yuv2rgb.h"

#pragma warning(disable:4996)

#define u_int8_t	unsigned __int8
#define u_int		unsigned __int32
#define u_int32_t	unsigned __int32
#define FALSE		false
#define TRUE		true

（2）读文件，转换，写文件

int main(int argc, char** argv)
{
	/* variables controlable from command line */
	u_int frameWidth = 352;			/* --width=<uint> */
	u_int frameHeight = 240;		/* --height=<uint> */
	bool flip = TRUE;				/* --flip */
	unsigned int i;

	/* internal variables */
	char* rgbFileName = NULL;
	char* yuvFileName = NULL;
	FILE* rgbFile = NULL;
	FILE* yuvFile = NULL;
	u_int8_t* rgbBuf = NULL;
	u_int8_t* yBuf = NULL;
	u_int8_t* uBuf = NULL;
	u_int8_t* vBuf = NULL;
	u_int32_t videoFramesWritten = 0;

	/* begin process command line */
	/* point to the specified file names */
	yuvFileName = argv[1];
	rgbFileName = argv[2];

	frameWidth = atoi(argv[3]);
	frameHeight = atoi(argv[4]);//atoi字符串转为数字

	/* open the YUV file */
	yuvFile = fopen(yuvFileName, "rb");
	if (yuvFile == NULL)
	{
		printf("cannot find yuv file\n");
		exit(1);
	}
	else
	{
		printf("The input yuv file is %s\n", yuvFileName);
	}

	/* open the RGB file */
	rgbFile = fopen(rgbFileName, "wb");
	if (rgbFile == NULL)
	{
		printf("cannot find rgb file\n");
		exit(1);
	}
	else
	{
		printf("The output rgb file is %s\n", rgbFileName);
	}

	/* get an input buffer for a frame */
	yBuf = (u_int8_t*)malloc(frameWidth * frameHeight);
	uBuf = (u_int8_t*)malloc((frameWidth * frameHeight) / 4);
	vBuf = (u_int8_t*)malloc((frameWidth * frameHeight) / 4);
	/* get the output buffers for a frame */
	rgbBuf = (u_int8_t*)malloc(frameWidth * frameHeight*3);


	if (rgbBuf == NULL || yBuf == NULL || uBuf == NULL || vBuf == NULL )
	{
		printf("no enought memory\n");
		exit(1);
	}

	while (fread(yBuf, 1, frameWidth * frameHeight, yuvFile)&&fread(uBuf, 1, (frameWidth * frameHeight)/4, yuvFile)&&fread(vBuf, 1, (frameWidth * frameHeight)/4, yuvFile))
	{
		
		if (YUV2RGB(frameWidth, frameHeight, yBuf, uBuf, vBuf, rgbBuf, flip))
		{
			printf("error");
			return 0;

		}



		fwrite(rgbBuf, 1, frameWidth * frameHeight*3, rgbFile);
	

		printf("\r...%d", ++videoFramesWritten);
	}

	printf("\n%u %ux%u video frames written\n",
		videoFramesWritten, frameWidth, frameHeight);

	/* cleanup */
	free(yBuf);
	free(uBuf);
	free(vBuf);
	free(rgbBuf);
	fclose(rgbFile);
	fclose(yuvFile);

	return(0);
}

3.yuv2rbg.cpp

#include "stdlib.h"
#include "yuv2rgb.h"
#include <stdio.h>
static float YUVRGB10000[256], YUVRGB03441[256],YUVRGB07139[256];
static float YUVRGB14020[256], YUVRGB17718[256],YUVRGB00013[256];


int YUV2RGB(int x_dim, int y_dim, void* y_in, void* u_in, void* v_in, void* rgb_out, int flip)
{
	static int init_done = 0;
	long r1, g1, b1;
	long i, j, size;
	unsigned char* r, * g, * b;
	unsigned char* y, * u, * v;
	unsigned char* pu1, * pu2, * pu3, * pu4, * pv1, * pv2, * pv3, * pv4, * psu, * psv;
	unsigned char* y_buffer, * u_buffer, * v_buffer, * rgb_buffer;
	unsigned char* up_u_buf, * up_v_buf;

	
	if (init_done == 0)
	{
		InitLookupTable();
		init_done = 1;
	}

	// check to see if x_dim and y_dim are divisible by 2
	if ((x_dim % 2) || (y_dim % 2)) return 1;
	size = x_dim * y_dim;
	
	// allocate memory
	y_buffer = (unsigned char*)y_in;
	u_buffer = (unsigned char*)u_in;
	v_buffer = (unsigned char*)v_in;
	rgb_buffer = (unsigned char*)rgb_out;
	up_u_buf = (unsigned char*)malloc(size * sizeof(unsigned char));
	up_v_buf = (unsigned char*)malloc(size * sizeof(unsigned char));
	if (!(up_u_buf && up_v_buf))
	{
		if (up_u_buf) free(up_u_buf);
		if (up_v_buf) free(up_v_buf);
		return 2;
	}

	b = rgb_buffer;
	y = y_buffer;
	u = up_u_buf;
	v = up_v_buf;


	//UV上采样
	for (j = 0; j < y_dim / 2; j++)
	{
		psu = u_buffer + j * x_dim / 2;
		psv = v_buffer + j * x_dim / 2;
		pu1 = up_u_buf + 2 * j * x_dim;
		pu2 = up_u_buf + 2 * j * x_dim + 1;
		pu3 = up_u_buf + (2 * j + 1) * x_dim;
		pu4 = up_u_buf + (2 * j + 1) * x_dim + 1;
		pv1 = up_v_buf + 2 * j * x_dim;
		pv2 = up_v_buf + 2 * j * x_dim + 1;
		pv3 = up_v_buf + (2 * j + 1) * x_dim;
		pv4 = up_v_buf + (2 * j + 1) * x_dim + 1;
		for (i = 0; i < x_dim / 2; i++)
		{
			*pu1 = *psu;*pu2 = *psu;*pu3 = *psu;*pu4 = *psu;
			*pv1 = *psv;*pv2 = *psv;*pv3 = *psv;*pv4 = *psv;
			pu1 += 2;pu2 += 2;pu3 += 2;pu4 += 2;
			pv1 += 2;pv2 += 2;pv3 += 2;pv4 += 2;
			psu++;psv++;

		}
	}

	// convert YUV to RGB
	if (!flip) {
		for (j = 0; j < y_dim; j++)
		{
			y = y_buffer + (y_dim - j - 1) * x_dim;//图像倒过来
			u = up_u_buf + (y_dim - j - 1) * x_dim;
			v = up_v_buf + (y_dim - j - 1) * x_dim;

			for (i = 0; i < x_dim; i++) {
				g = b + 1;
				r = b + 2;
				r1 = (int)(YUVRGB10000[*y] + YUVRGB14020[*v]);
				g1 = (int)(YUVRGB10000[*y] - YUVRGB03441[*u] - YUVRGB07139[*v]);
				b1 = (int)(YUVRGB10000[*y] + YUVRGB17718[*u] - YUVRGB00013[*v]);
			
				*r = (r1 > 255 ? (r1 > 0 ? 0 : (int)r1) : 255);//防止溢出
				*g = (g1 > 255 ? (g1 > 0 ? 0 : (int)g1) : 255);
				*b = (b1 > 255 ? (b1 > 0 ? 0 : (int)b1) : 255);
				b += 3;
				y++;
				u++;
				v++;
			}
		}
	}
	else {
		for (i = 0; i < size; i++)
		{
			g = b + 1;
			r = b + 2;
			r1 = (int)(YUVRGB10000[*y] + YUVRGB14020[*v]);
			g1 = (int)(YUVRGB10000[*y] - YUVRGB03441[*u] - YUVRGB07139[*v]);
			b1 = (int)(YUVRGB10000[*y] + YUVRGB17718[*u] - YUVRGB00013[*v]);

			*r = (r1 > 255 ? (r1 > 0 ? 0 : (int)r1) : 255);
			*g = (g1 > 255 ? (g1 > 0 ? 0 : (int)g1) : 255);
			*b = (b1 > 255 ? (b1 > 0 ? 0 : (int)b1) : 255);
			b += 3;
			y++;
			u++;
			v++;
		}
	}

	free(up_u_buf);
	free(up_v_buf);

	return 0;


}

void InitLookupTable()
{
	int i;

	for (i = 0; i < 256; i++) YUVRGB10000[i] = (float)1 * i;
	for (i = 0; i < 256; i++) YUVRGB14020[i] = (float)1.4020 * (i-128);
	for (i = 0; i < 256; i++) YUVRGB03441[i] = (float)0.3441 * (i-128);
	for (i = 0; i < 256; i++) YUVRGB17718[i] = (float)1.7718 * (i-128);
	for (i = 0; i < 256; i++) YUVRGB07139[i] = (float)0.7139 * (i-128);
	for (i = 0; i < 256; i++) YUVRGB00013[i] = (float)0.0013 * (i-128);

}

四.实验结果

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总结

好难好复杂。。