像素数据格式的转换yuv转rgba

本文介绍如何使用ffmpeg中的接口转换像素数据格式.

假定现有 yuv.yuv(YUV420P格式)文件需要转为RGBA格式
将rgb.rgb转成yuv格式

#include <iostream>
#include <fstream>
using namespace std;
extern "C"{
#include <libavcodec/avcodec.h>
#include <libswscale/swscale.h>
}
//预处理指令导入库
#pragma comment(lib, "avcodec.lib")
#pragma comment(lib, "avutil.lib")
#pragma comment(lib, "swscale.lib")

#define YUV_FILE "yuv.yuv"
#define RGBA_FILE "rgb.rgb"

#define YUV_WIDTH 400
#define YUV_HEIGHT 300

#define RGB_WIDTH 800
#define RGB_HEIGHT 600

int main()
{
//1,申请3个用于存放yuv数据的数组 并设置好linesize
	unsigned char *yuv[3];
	int yuv_linesize[3] = { YUV_WIDTH, YUV_WIDTH / 2, YUV_WIDTH / 2 };
	yuv[0] = new unsigned char[YUV_WIDTH * YUV_HEIGHT ];
	yuv[1] = new unsigned char[YUV_WIDTH * YUV_HEIGHT / 4];
	yuv[2] = new unsigned char[YUV_WIDTH * YUV_HEIGHT  / 4];
//2,申请一个用于存放RGBA数据的数组 并设置好linesize
	unsigned char* rgba = new unsigned char[RGB_WIDTH * RGB_HEIGHT *4];
	int rgba_linesize = RGB_WIDTH * 4;

//3,打开YUV_FILE文件 和 RGBA_FILE
	ifstream ifs;
	ifs.open(YUV_FILE, ios::binary);
	if(!ifs){
		cout << "open file failed" << endl;
		return -1;
	}
	ofstream ofs;
	ofs.open("yuv2rgb.rgb", ios::binary);
	if(!ofs){
		cout << "open file yuv2rgb.rgb file failed" << endl;
		return -2;
	}
//4, 循环转换至文件结束 转换要用到SwsContex对象
	SwsContext* yuv2rgb = nullptr; //yuv -> rgba
	for(;;){
		//读取一帧的yuv数据
		ifs.read((char*)yuv[0], YUV_WIDTH * YUV_HEIGHT);
		ifs.read((char*)yuv[1], YUV_WIDTH * YUV_HEIGHT / 4);
		ifs.read((char*)yuv[2], YUV_WIDTH * YUV_HEIGHT / 4);
		//获取yuv转RGBA的上下文
		yuv2rgb = sws_getCachedContext(
				yuv2rgb,	//转换上下文, 如果是nullptr新建, 不是nullptr判断是否与现有参数一致, 一致直接返回, 不一致先清理原数据, 再新建
				YUV_WIDTH, YUV_HEIGHT, //输入数据的宽高
				 AV_PIX_FMT_YUV420P,  //输入的像素格式
				 RGB_WIDTH, RGB_HEIGHT, //输出数据的宽高
				 AV_PIX_FMT_RGBA,		//输出的像素格式
				 SWS_BILINEAR, 	 		//选择变换算法, 双线性插值算法
				 0,0,0					//过滤器参数
				);
		if(!yuv2rgb){
			cout << "sws_getCacheContext failed" << endl;
			return -4;
		}
		//通过格式转换上下文yuv2rgb开始转换
		int ret = sws_scale(yuv2rgb,
					yuv,		//输入数据
					yuv_linesize, //输入数据行字节数
					0,			//图像层次
					YUV_HEIGHT, //输入高度
					&rgba,		//输出的数据
					&rgba_linesize //输出的行大小
		);
		cout << ret << " " << flush;
		//写入文件
		ofs.write((char*)rgba, RGB_WIDTH  * RGB_HEIGHT  * 4);
		if(ifs.eof()) break;
	}
	ifs.close();
	ofs.close();



//rgb转yuv
	ifs.open(RGBA_FILE, ios::binary);
		if(!ifs){
		cout << "open file failed" << endl;
		return -5;
	}
	ofs.open("rgb2yuv.yuv", ios::binary);
	if(!ifs){
		cout << "open rgb2yuv.yuv failed" << endl;
		return -6;
	}
	SwsContext* rgb2yuv = nullptr; //rgba -> yuv
	for(;;){
		ifs.read((char*)rgba, RGB_WIDTH * RGB_HEIGHT * 4);
				rgb2yuv = sws_getCachedContext(
			rgb2yuv, //转换上下文, NULL新创建, 非NULL判断与现有参数是否一致, 一致直接返回, 不一致先清理原数据,然后再创建
			RGB_WIDTH, RGB_HEIGHT,  // 输入宽高
			AV_PIX_FMT_RGBA,		//输入像素格式
			YUV_WIDTH, YUV_HEIGHT,	//输出宽高
			AV_PIX_FMT_YUV420P,		//输出像素格式
			SWS_BILINEAR,			//选择变换算法, 双线性插值算法
			0, 0, 0					//过滤器参数
		);
		if(!rgb2yuv){
			cout << "sws_getCachedContext failed" << endl;
			return -7;
		}
		int ret = sws_scale(rgb2yuv,
			&rgba,			//输入数据
			&rgba_linesize,	//输入数据行字节数
			0,				//图像层次
			RGB_HEIGHT,			//输入高度
			yuv,			//输出的数据
			yuv_linesize //输出的行大小
		);
		cout << ret << " " << flush;


		ofs.write((char *)yuv[0], YUV_WIDTH * YUV_HEIGHT);
		ofs.write((char*)yuv[1], YUV_WIDTH * YUV_HEIGHT /4);
		ofs.write((char*)yuv[2], YUV_WIDTH* YUV_HEIGHT / 4);

		if (ifs.eof()) break;
	}





	ifs.close();
	ofs.close();
	delete yuv[0]; //别忘了清理空间
	delete yuv[1]; //别忘了清理空间
	delete yuv[2]; //别忘了清理空间
	delete rgba;//别忘了清理空间
	
	
}