cv::Mat到YUV420的转换《转》

某些特定场合我们会经常遇到yuv420格式的视频文件，这种视频帧无法直接用于opencv，故而，需要进行格式转换；幸运的是，opencv提供了rgb到yuv420的格式转换函数；下面给出基本用法；

函数1：读取avi格式的视频文件，转换成Yuv420格式，并写入文件；

void WriteYuv()
{
    cv::VideoCapture vc;
    bool flag = vc.open("S1000008.avi");
    if (!flag)
    {
        printf("avi file open error \n");
        system("pause");
        exit(-);
    }  

    int frmCount = vc.get(CV_CAP_PROP_FRAME_COUNT);
    frmCount -= ;
    printf("frmCount: %d \n", frmCount);  

    int w = vc.get(CV_CAP_PROP_FRAME_WIDTH);
    int h = vc.get(CV_CAP_PROP_FRAME_HEIGHT);
    int bufLen = w*h*/;
    unsigned char* pYuvBuf = new unsigned char[bufLen];
    FILE* pFileOut = fopen("result.yuv", "w+");
    if (!pFileOut)
    {
        printf("pFileOut open error \n");
        system("pause");
        exit(-);
    }
    printf("pFileOut open ok \n");  

    for (int i=; i<frmCount; i++)
    {
        printf("%d/%d \n", i+, frmCount);  

        cv::Mat srcImg;
        vc>>srcImg;  

        cv::imshow("img", srcImg);
        cv::waitKey();  

        cv::Mat yuvImg;
        cv::cvtColor(srcImg, yuvImg, CV_BGR2YUV_I420);
        memcpy(pYuvBuf, yuvImg.data, bufLen*sizeof(unsigned char));  

        fwrite(pYuvBuf, bufLen*sizeof(unsigned char), , pFileOut);
    }  

    fclose(pFileOut);
    delete[] pYuvBuf;
}  

函数二，读取yuv420格式的文件，转换成cv::Mat格式，并予以显示：

void DisplayYUV()
{
    int w = ;
    int h = ;
    printf("yuv file w: %d, h: %d \n", w, h);  

    FILE* pFileIn = fopen("result.yuv", "rb+");
    int bufLen = w*h*/;
    unsigned char* pYuvBuf = new unsigned char[bufLen];
    int iCount = ;  

    for(int i=; i<; i++)
    {
        fread(pYuvBuf, bufLen*sizeof(unsigned char), , pFileIn);  

        cv::Mat yuvImg;
        yuvImg.create(h*/, w, CV_8UC1);
        memcpy(yuvImg.data, pYuvBuf, bufLen*sizeof(unsigned char));
        cv::Mat rgbImg;
        cv::cvtColor(yuvImg, rgbImg, CV_YUV2BGR_I420);  

        cv::imshow("img", yuvImg);
        cv::waitKey();  

        printf("%d \n", iCount++);
    }  

    delete[] pYuvBuf;  

    fclose(pFileIn);
}  

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原贴地址：https://blog.csdn.net/carson2005/article/details/38351717