视频解析

解码高分别率

如果图片分辨率太高，影响解码速率，可以采用降采样后再解码

参考opencv的pyrDown降采样接口

cv::pyrDown(yuv, yuvDown, cv::Size(yuv.cols / 2, yuv.rows / 2));

YUV转RGB，不同实现方式效率比较

转换效率分析

测试序列：1920*1080

测试环境：OpenCV2.4.8, FFmpeg2.0, YUV2RGB v0.03

https://blog.csdn.net/lg1259156776/article/details/53071961

Method	Time(ms)
YV12ToBGR24_Native	83.7263
YV12ToBGR24_Table	54.2376
YV12ToBGR24_OpenCV	26.0529
YV12ToBGR24_FFmpeg	3.41499
YV12ToBGR24_Pinknoise	14.1215

附录:

YV12转RGB32

此算法解析低分辨率效率还行，但是高于2K的效率就不行了，解析3392*2008分辨率的视频 125ms一帧。会导致视频不流畅

bool YV12_to_RGB32(unsigned char* pYV12, unsigned char* pRGB32, int iWidth, int iHeight)
{
    if (!pYV12 || !pRGB32)
        return false;

    const long nYLen = long(iHeight * iWidth);
    const int nHfWidth = (iWidth >> 1);

    if (nYLen < 1 || nHfWidth < 1)
        return false;

    unsigned char* yData = pYV12;
    unsigned char* vData = pYV12 + iWidth*iHeight + (iHeight / 2)*(iWidth / 2);//&vData[nYLen >> 2];
    unsigned char* uData = pYV12 + iWidth*iHeight;// &yData[nYLen];
    if (!uData || !vData)
        return false;

    int rgb[4];
    int jCol, iRow;
    for (iRow = 0; iRow < iHeight; iRow++)
    {
        for (jCol = 0; jCol < iWidth; jCol++)
        {
            rgb[3] = 1;

            int Y = yData[iRow*iWidth + jCol];
            int U = uData[(iRow / 2)*(iWidth / 2) + (jCol / 2)];
            int V = vData[(iRow / 2)*(iWidth / 2) + (jCol / 2)];
            int R = Y + (U - 128) + (((U - 128) * 103) >> 8);
            int G = Y - (((V - 128) * 88) >> 8) - (((U - 128) * 183) >> 8);
            int B = Y + (V - 128) + (((V - 128) * 198) >> 8);

            // r分量值
            R = R<0 ? 0 : R;
            rgb[2] = R > 255 ? 255 : R;
            // g分量值
            G = G<0 ? 0 : G;
            rgb[1] = G>255 ? 255 : G;
            // b分量值
            B = B<0 ? 0 : B;
            rgb[0] = B>255 ? 255 : B;
            pRGB32[4 * (iRow*iWidth + jCol) + 0] = rgb[0];
            pRGB32[4 * (iRow*iWidth + jCol) + 1] = rgb[1];
            pRGB32[4 * (iRow*iWidth + jCol) + 2] = rgb[2];
            pRGB32[4 * (iRow*iWidth + jCol) + 3] = rgb[3];
        }
    }

    return true;
}