RGB图片文件转换为YUV格式后，将YUV数据以二进制形式写到文件中，使用7yuv软件查看。

#include<iostream>
#include<cstdio>
#include<string>
#include"opencv2/opencv.hpp"#include "libyuv/scale.h"
#include "libyuv/convert_from.h"using namespace std;
/*
int I420ToNV21(const uint8* src_y, int src_stride_y,const uint8* src_u, int src_stride_u,const uint8* src_v, int src_stride_v,uint8* dst_y, int dst_stride_y,uint8* dst_vu, int dst_stride_vu,int width, int height);
*/
const std::string strCHE = "../unit_test/testdata/src.jpg";
const std::string strSHAN = "../unit_test/testdata/shan.jpg";
const std::string strTA = "../unit_test/testdata/ta.jpg";int main(int argc, char* argv[])
{cv::Mat src_rgb = cv::imread(strTA);cv::Mat src_yuv_i420;// transform RGB to YUV-I420cv::cvtColor(src_rgb, src_yuv_i420, CV_BGR2YUV_I420);int nWidth_rgb = src_rgb.cols;int nHeight_rgb = src_rgb.rows;int src_stride_y = nWidth_rgb;int src_stride_u = nWidth_rgb / 2;int src_stride_v = nWidth_rgb / 2;int nWidth_yuv = src_yuv_i420.cols;int nHeight_yuv = src_yuv_i420.rows;cv::Mat dst_yuv_nv21(nHeight_rgb * 3 / 2, nWidth_rgb, CV_8UC1);int dst_stride_y = nWidth_rgb;int dst_stride_vu = nWidth_rgb;libyuv::I420ToNV21(src_yuv_i420.data, src_stride_y, src_yuv_i420.data + nWidth_rgb * nHeight_rgb, src_stride_u, src_yuv_i420.data + nWidth_rgb * nHeight_rgb * 5 / 4, src_stride_v,dst_yuv_nv21.data, dst_stride_y, dst_yuv_nv21.data + nWidth_rgb * nHeight_rgb, dst_stride_vu, nWidth_yuv, nHeight_yuv);//cv::imwrite("src_yuv_nv21.jpg", dst_yuv_nv21);FILE* fp = fopen("out_nv21_mat.yuv", "wb");fwrite(dst_yuv_nv21.data, 1, nWidth_yuv * nHeight_yuv * 3 / 2, fp);fclose(fp);fp = NULL;return 0;
}

原图

效果图如下