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YUV格式学习:YUV422P、YV16、NV16、NV61格式转换成RGB24

对于YUV422的格式,网上有一大堆资料,这里就不说了。直奔主题,给出如何转换的函数,一如既往,只用代码说事。
YUV422有打包格式(Packed),一如前文所述。同时还有平面格式(Planar),即Y、U、V是分开存储的,每个分量占一块地方,其中Y为width*height,而U、V合占width*height,该种格式每个像素占16比特。根据U、V的顺序,分出2种格式,U前V后即YUV422P,也叫I422,V前U后,叫YV16(YV表示Y后面跟着V,16表示16bit)。另外,还有一种变态的半平面格式(Semi-planar),即Y单独占一块地方,但其后U、V又紧挨着排在一起,根据U、V的顺序,又有2种,U前V后叫NV16,在国内好像很多人叫它为YUV422SP格式;V前U后叫NV61。不过这种格式似乎不太受VLC欢迎(具体可去看看VLC的wiki)。
先给出YUV422平面格式的转换函数,如下:

/**
内存分布
                    w
            +--------------------+
            |Y0Y1Y2Y3...         |
            |...                 |   h
            |...                 |
            |                    |
            +--------------------+
            |U0U1      |
            |...       |   h
            |...       |
            |          |
            +----------+
            |V0V1      |
            |...       |  h
            |...       |
            |          |
            +----------+
                w/2
*/
void yuv422p_to_rgb24(YUV_TYPE type, unsigned char* yuv422p, unsigned char* rgb, int width, int height)
{
    int y, cb, cr;
    int r, g, b;
    int i = 0;
    unsigned char* p_y;
    unsigned char* p_u;
    unsigned char* p_v;
    unsigned char* p_rgb;

    p_y = yuv422p;
    p_u = p_y + width * height;
    p_v = p_u + width * height / 2;

    if (type == FMT_YV16)
    {
        p_v = p_y + width * height;
        p_u = p_u + width * height / 2;
    }
    p_rgb = rgb;

    init_yuv422p_table();

    for (i = 0; i < width * height / 2; i++)
    {
        y  = p_y[0];
        cb = p_u[0];
        cr = p_v[0];

        r = MAX (0, MIN (255, (V[cr] + Y1[y])/10000));   //R value
        b = MAX (0, MIN (255, (U[cb] + Y1[y])/10000));   //B value
        g = MAX (0, MIN (255, (Y2[y] - 5094*(r) - 1942*(b))/10000)); //G value

        // 此处可调整RGB排序,BMP图片排序为BGR
        // 默认排序为:RGB
        p_rgb[0] = r;
        p_rgb[1] = g;
        p_rgb[2] = b;

        y  = p_y[1];
        cb = p_u[0];
        cr = p_v[0];
        r = MAX (0, MIN (255, (V[cr] + Y1[y])/10000));   //R value
        b = MAX (0, MIN (255, (U[cb] + Y1[y])/10000));   //B value
        g = MAX (0, MIN (255, (Y2[y] - 5094*(r) - 1942*(b))/10000)); //G value

        p_rgb[3] = r;
        p_rgb[4] = g;
        p_rgb[5] = b;

        p_y += 2;
        p_u += 1;
        p_v += 1;
        p_rgb += 6;
    }
}

接着给出NV16、NV61转换成RGB的函数,如下:

/**
内存分布
                    w
            +--------------------+
            |Y0Y1Y2Y3...         |
            |...                 |   h
            |...                 |
            |                    |
            +--------------------+
            |U0V0U1V1            |
            |...                 |   h
            |...                 |
            |                    |
            +--------------------+
                w/2
UV交织为NV16,VU交织为NV61
可以与上一函数合并,但方便查看,还是不合并
*/
void yuv422sp_to_rgb24(YUV_TYPE type, unsigned char* yuv422sp, unsigned char* rgb, int width, int height)
{
    int y, cb, cr;
    int r, g, b;
    int i = 0;
    unsigned char* p_y;
    unsigned char* p_uv;
    unsigned char* p_rgb;

    p_y = yuv422sp;
    p_uv = p_y + width * height;    // uv分量在Y后面
    p_rgb = rgb;

    init_yuv422p_table();

    for (i = 0; i < width * height / 2; i++)
    {
        y  = p_y[0];
        if (type ==  FMT_NV16)
        {
            cb = p_uv[0];
            cr = p_uv[1];    // v紧跟u,在u的下一个位置
        }
        if (type == FMT_NV61)
        {
            cr = p_uv[0];
            cb = p_uv[1];    // u紧跟v,在v的下一个位置
        }

        r = MAX (0, MIN (255, (V[cr] + Y1[y])/10000));   //R value
        b = MAX (0, MIN (255, (U[cb] + Y1[y])/10000));   //B value
        g = MAX (0, MIN (255, (Y2[y] - 5094*(r) - 1942*(b))/10000)); //G value

        // 此处可调整RGB排序,BMP图片排序为BGR
        // 默认排序为:RGB
        p_rgb[0] = r;
        p_rgb[1] = g;
        p_rgb[2] = b;

        y  = p_y[1];
        if (type ==  FMT_NV16)
        {
            cb = p_uv[0];
            cr = p_uv[1];
        }
        if (type ==  FMT_NV61)
        {
            cr = p_uv[0];
            cb = p_uv[1];
        }

        r = MAX (0, MIN (255, (V[cr] + Y1[y])/10000));   //R value
        b = MAX (0, MIN (255, (U[cb] + Y1[y])/10000));   //B value
        g = MAX (0, MIN (255, (Y2[y] - 5094*(r) - 1942*(b))/10000)); //G value

        p_rgb[3] = r;
        p_rgb[4] = g;
        p_rgb[5] = b;

        p_y += 2;
        p_uv += 2;
        p_rgb += 6;
    }
}

参考资料:
http://www.fourcc.org/yuv.php
https://wiki.videolan.org/YUV/

李迟 2015.8.5 晚上

本文固定链接: http://www.latelee.org/my-study/yuv-learning-yuv422p-to-rgb24.html

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