AVFrame转换到Mat，yuv420p转换到RGB源代码

FFmpeg中AVFrame到OpenCV中Mat的两种转换方法

方法一：查表法

void AVFrame2Img(AVFrame *pFrame, cv::Mat& img)
{
    int frameHeight = pFrame->height;
    int frameWidth = pFrame->width;
    int channels = 3;
    //输出图像分配内存
    img = cv::Mat::zeros(frameHeight, frameWidth, CV_8UC3);
    //反转图像
    pFrame->data[0] += pFrame->linesize[0] * (frameHeight - 1);
    pFrame->linesize[0] *= -1;
    pFrame->data[1] += pFrame->linesize[1] * (frameHeight / 2 - 1);
    pFrame->linesize[1] *= -1;
    pFrame->data[2] += pFrame->linesize[2] * (frameHeight / 2 - 1);
    pFrame->linesize[2] *= -1;

    //创建保存yuv数据的buffer
    uchar* pDecodedBuffer = (uchar*)malloc(frameHeight*frameWidth * sizeof(uchar)*channels);

    //从AVFrame中获取yuv420p数据，并保存到buffer
    int i, j, k;
    //拷贝y分量
    for (i = 0; i < frameHeight; i++)
    {
        memcpy(pDecodedBuffer + frameWidth*i,
            pFrame->data[0] + pFrame->linesize[0] * i,
            frameWidth);
    }
    //拷贝u分量
    for (j = 0; j < frameHeight / 2; j++)
    {
        memcpy(pDecodedBuffer + frameWidth*i + frameWidth / 2 * j,
            pFrame->data[1] + pFrame->linesize[1] * j,
            frameWidth / 2);
    }
    //拷贝v分量
    for (k = 0; k < frameHeight / 2; k++)
    {
        memcpy(pDecodedBuffer + frameWidth*i + frameWidth / 2 * j + frameWidth / 2 * k,
            pFrame->data[2] + pFrame->linesize[2] * k,
            frameWidth / 2);
    }

    //将buffer中的yuv420p数据转换为RGB;
    YUV2RGB(pDecodedBuffer, frameWidth, frameHeight, channels, img.data);

    //释放buffer
    free(pDecodedBuffer);
}

 子函数YUV2RGB( )实现yuv420p到RGB的转换

bool YUV2RGB(uchar* pYuvBuf, int nWidth, int nHeight, int channels, uchar* pRgbBuf)
{
#define PIXELSIZE nWidth * nHeight  
    const int Table_fv1[256] = { -180, -179, -177, -176, -174, -173, -172, -170, -169, -167, -166, -165, -163, -162, -160, -159, -158, -156, -155, -153, -152, -151, -149, -148, -146, -145, -144, -142, -141, -139, -138, -137, -135, -134, -132, -131, -130, -128, -127, -125, -124, -123, -121, -120, -118, -117, -115, -114, -113, -111, -110, -108, -107, -106, -104, -103, -101, -100, -99, -97, -96, -94, -93, -92, -90, -89, -87, -86, -85, -83, -82, -80, -79, -78, -76, -75, -73, -72, -71, -69, -68, -66, -65, -64, -62, -61, -59, -58, -57, -55, -54, -52, -51, -50, -48, -47, -45, -44, -43, -41, -40, -38, -37, -36, -34, -33, -31, -30, -29, -27, -26, -24, -23, -22, -20, -19, -17, -16, -15, -13, -12, -10, -9, -8, -6, -5, -3, -2, 0, 1, 2, 4, 5, 7, 8, 9, 11, 12, 14, 15, 16, 18, 19, 21, 22, 23, 25, 26, 28, 29, 30, 32, 33, 35, 36, 37, 39, 40, 42, 43, 44, 46, 47, 49, 50, 51, 53, 54, 56, 57, 58, 60, 61, 63, 64, 65, 67, 68, 70, 71, 72, 74, 75, 77, 78, 79, 81, 82, 84, 85, 86, 88, 89, 91, 92, 93, 95, 96, 98, 99, 100, 102, 103, 105, 106, 107, 109, 110, 112, 113, 114, 116, 117, 119, 120, 122, 123, 124, 126, 127, 129, 130, 131, 133, 134, 136, 137, 138, 140, 141, 143, 144, 145, 147, 148, 150, 151, 152, 154, 155, 157, 158, 159, 161, 162, 164, 165, 166, 168, 169, 171, 172, 173, 175, 176, 178 };
    const int Table_fv2[256] = { -92, -91, -91, -90, -89, -88, -88, -87, -86, -86, -85, -84, -83, -83, -82, -81, -81, -80, -79, -78, -78, -77, -76, -76, -75, -74, -73, -73, -72, -71, -71, -70, -69, -68, -68, -67, -66, -66, -65, -64, -63, -63, -62, -61, -61, -60, -59, -58, -58, -57, -56, -56, -55, -54, -53, -53, -52, -51, -51, -50, -49, -48, -48, -47, -46, -46, -45, -44, -43, -43, -42, -41, -41, -40, -39, -38, -38, -37, -36, -36, -35, -34, -33, -33, -32, -31, -31, -30, -29, -28, -28, -27, -26, -26, -25, -24, -23, -23, -22, -21, -21, -20, -19, -18, -18, -17, -16, -16, -15, -14, -13, -13, -12, -11, -11, -10, -9, -8, -8, -7, -6, -6, -5, -4, -3, -3, -2, -1, 0, 0, 1, 2, 2, 3, 4, 5, 5, 6, 7, 7, 8, 9, 10, 10, 11, 12, 12, 13, 14, 15, 15, 16, 17, 17, 18, 19, 20, 20, 21, 22, 22, 23, 24, 25, 25, 26, 27, 27, 28, 29, 30, 30, 31, 32, 32, 33, 34, 35, 35, 36, 37, 37, 38, 39, 40, 40, 41, 42, 42, 43, 44, 45, 45, 46, 47, 47, 48, 49, 50, 50, 51, 52, 52, 53, 54, 55, 55, 56, 57, 57, 58, 59, 60, 60, 61, 62, 62, 63, 64, 65, 65, 66, 67, 67, 68, 69, 70, 70, 71, 72, 72, 73, 74, 75, 75, 76, 77, 77, 78, 79, 80, 80, 81, 82, 82, 83, 84, 85, 85, 86, 87, 87, 88, 89, 90, 90 };
    const int Table_fu1[256] = { -44, -44, -44, -43, -43, -43, -42, -42, -42, -41, -41, -41, -40, -40, -40, -39, -39, -39, -38, -38, -38, -37, -37, -37, -36, -36, -36, -35, -35, -35, -34, -34, -33, -33, -33, -32, -32, -32, -31, -31, -31, -30, -30, -30, -29, -29, -29, -28, -28, -28, -27, -27, -27, -26, -26, -26, -25, -25, -25, -24, -24, -24, -23, -23, -22, -22, -22, -21, -21, -21, -20, -20, -20, -19, -19, -19, -18, -18, -18, -17, -17, -17, -16, -16, -16, -15, -15, -15, -14, -14, -14, -13, -13, -13, -12, -12, -11, -11, -11, -10, -10, -10, -9, -9, -9, -8, -8, -8, -7, -7, -7, -6, -6, -6, -5, -5, -5, -4, -4, -4, -3, -3, -3, -2, -2, -2, -1, -1, 0, 0, 0, 1, 1, 1, 2, 2, 2, 3, 3, 3, 4, 4, 4, 5, 5, 5, 6, 6, 6, 7, 7, 7, 8, 8, 8, 9, 9, 9, 10, 10, 11, 11, 11, 12, 12, 12, 13, 13, 13, 14, 14, 14, 15, 15, 15, 16, 16, 16, 17, 17, 17, 18, 18, 18, 19, 19, 19, 20, 20, 20, 21, 21, 22, 22, 22, 23, 23, 23, 24, 24, 24, 25, 25, 25, 26, 26, 26, 27, 27, 27, 28, 28, 28, 29, 29, 29, 30, 30, 30, 31, 31, 31, 32, 32, 33, 33, 33, 34, 34, 34, 35, 35, 35, 36, 36, 36, 37, 37, 37, 38, 38, 38, 39, 39, 39, 40, 40, 40, 41, 41, 41, 42, 42, 42, 43, 43 };
    const int Table_fu2[256] = { -227, -226, -224, -222, -220, -219, -217, -215, -213, -212, -210, -208, -206, -204, -203, -201, -199, -197, -196, -194, -192, -190, -188, -187, -185, -183, -181, -180, -178, -176, -174, -173, -171, -169, -167, -165, -164, -162, -160, -158, -157, -155, -153, -151, -149, -148, -146, -144, -142, -141, -139, -137, -135, -134, -132, -130, -128, -126, -125, -123, -121, -119, -118, -116, -114, -112, -110, -109, -107, -105, -103, -102, -100, -98, -96, -94, -93, -91, -89, -87, -86, -84, -82, -80, -79, -77, -75, -73, -71, -70, -68, -66, -64, -63, -61, -59, -57, -55, -54, -52, -50, -48, -47, -45, -43, -41, -40, -38, -36, -34, -32, -31, -29, -27, -25, -24, -22, -20, -18, -16, -15, -13, -11, -9, -8, -6, -4, -2, 0, 1, 3, 5, 7, 8, 10, 12, 14, 15, 17, 19, 21, 23, 24, 26, 28, 30, 31, 33, 35, 37, 39, 40, 42, 44, 46, 47, 49, 51, 53, 54, 56, 58, 60, 62, 63, 65, 67, 69, 70, 72, 74, 76, 78, 79, 81, 83, 85, 86, 88, 90, 92, 93, 95, 97, 99, 101, 102, 104, 106, 108, 109, 111, 113, 115, 117, 118, 120, 122, 124, 125, 127, 129, 131, 133, 134, 136, 138, 140, 141, 143, 145, 147, 148, 150, 152, 154, 156, 157, 159, 161, 163, 164, 166, 168, 170, 172, 173, 175, 177, 179, 180, 182, 184, 186, 187, 189, 191, 193, 195, 196, 198, 200, 202, 203, 205, 207, 209, 211, 212, 214, 216, 218, 219, 221, 223, 225 };
    int len = channels * nWidth * nHeight;
    if (!pYuvBuf || !pRgbBuf)
        return false;
    const long nYLen = long(PIXELSIZE);
    const int nHfWidth = (nWidth >> 1);
    if (nYLen<1 || nHfWidth<1)
        return false;
    // Y data  
    unsigned char* yData = pYuvBuf;
    // v data  
    unsigned char* vData = &yData[nYLen];
    // u data  
    unsigned char* uData = &vData[nYLen >> 2];
    if (!uData || !vData)
        return false;
    int rgb[3];
    int i, j, m, n, x, y, pu, pv, py, rdif, invgdif, bdif;
    m = -nWidth;
    n = -nHfWidth;
    bool addhalf = true;
    for (y = 0; y<nHeight; y++) {
        m += nWidth;
        if (addhalf) {
            n += nHfWidth;
            addhalf = false;
        }
        else {
            addhalf = true;
        }
        for (x = 0; x<nWidth; x++) {
            i = m + x;
            j = n + (x >> 1);
            py = yData[i];
            // search tables to get rdif invgdif and bidif  
            rdif = Table_fv1[vData[j]];    // fv1  
            invgdif = Table_fu1[uData[j]] + Table_fv2[vData[j]]; // fu1+fv2  
            bdif = Table_fu2[uData[j]]; // fu2       
            rgb[0] = py + rdif;    // R  
            rgb[1] = py - invgdif; // G  
            rgb[2] = py + bdif;    // B  
            j = nYLen - nWidth - m + x;
            i = (j << 1) + j;
            // copy this pixel to rgb data  
            for (j = 0; j<3; j++)
            {
                if (rgb[j] >= 0 && rgb[j] <= 255) {
                    pRgbBuf[i + j] = rgb[j];
                }
                else {
                    pRgbBuf[i + j] = (rgb[j] < 0) ? 0 : 255;
                }
            }
        }
    }
    return true;
}

 

方法二、逐像素转换法：

void AVFrame2Img(AVFrame *pFrame, cv::Mat& img)
{
    int frameHeight = pFrame->height;
    int frameWidth = pFrame->width;
    int channels = 3;
    //输出图像分配内存
    img = cv::Mat::zeros(frameHeight, frameWidth, CV_8UC3);

    //创建保存yuv数据的buffer
    uchar* pDecodedBuffer = (uchar*)malloc(frameHeight*frameWidth * sizeof(uchar)*channels);

    //从AVFrame中获取yuv420p数据，并保存到buffer
    int i, j, k;
    //拷贝y分量
    for (i = 0; i < frameHeight; i++)
    {
        memcpy(pDecodedBuffer + frameWidth*i,
            pFrame->data[0] + pFrame->linesize[0] * i,
            frameWidth);
    }
    //拷贝u分量
    for (j = 0; j < frameHeight / 2; j++)
    {
        memcpy(pDecodedBuffer + frameWidth*i + frameWidth / 2 * j,
            pFrame->data[1] + pFrame->linesize[1] * j,
            frameWidth / 2);
    }
    //拷贝v分量
    for (k = 0; k < frameHeight / 2; k++)
    {
        memcpy(pDecodedBuffer + frameWidth*i + frameWidth / 2 * j + frameWidth / 2 * k,
            pFrame->data[2] + pFrame->linesize[2] * k,
            frameWidth / 2);
    }

    //将buffer中的yuv420p数据转换为RGB;
    Yuv420p2Rgb32(pDecodedBuffer, img.data, frameWidth, frameHeight);

    //释放buffer
    free(pDecodedBuffer);
}

 

子函数Yuv420p2Rgb32( )函数实现yuv420p到RGB32的转换

void Yuv420p2Rgb32(const uchar *yuvBuffer_in, const uchar *rgbBuffer_out, int width, int height)
{
    uchar *yuvBuffer = (uchar *)yuvBuffer_in;
    uchar *rgb32Buffer = (uchar *)rgbBuffer_out;

    int channels = 3;

    for (int y = 0; y < height; y++)
    {
        for (int x = 0; x < width; x++)
        {
            int index = y * width + x;

            int indexY = y * width + x;
            int indexU = width * height + y / 2 * width / 2 + x / 2;
            int indexV = width * height + width * height / 4 + y / 2 * width / 2 + x / 2;

            uchar Y = yuvBuffer[indexY];
            uchar U = yuvBuffer[indexU];
            uchar V = yuvBuffer[indexV];
            
            int R = Y + 1.402 * (V - 128);
            int G = Y - 0.34413 * (U - 128) - 0.71414*(V - 128);
            int B = Y + 1.772*(U - 128);
            R = (R < 0) ? 0 : R;
            G = (G < 0) ? 0 : G;
            B = (B < 0) ? 0 : B;
            R = (R > 255) ? 255 : R;
            G = (G > 255) ? 255 : G;
            B = (B > 255) ? 255 : B;

            rgb32Buffer[(y*width + x)*channels + 2] = uchar(R);
            rgb32Buffer[(y*width + x)*channels + 1] = uchar(G);
            rgb32Buffer[(y*width + x)*channels + 0] = uchar(B);
        }
    }
}