YUV422显示视频格式解释

H.264编码器输入要YUV420，而解码器解码之后显示一般又要YUV422，并且视频采集芯片输出往往也是YUV422，下面以我一个实际使用为例说一下YUV422格式：

/* YUV4:2:2格式(这是初始化背景为纯色，所以用了同一个Y) */
/* Black color in UYVY format */
#define UYVY_BLACK/*Y Cr Y Cb*/ 0x10801080/*black*/ /*blue:0x286e28ef red:0x51ef515b green:0x90239036/*/
/* DM6446中的测试代码，整个宏像素赋值 */
    for (bufIdx=; bufIdx < NUM_DISPLAY_BUFS; bufIdx++) {
        /* Clear the video buffer */
        buf = (unsigned int *) virtDisplays[bufIdx];

        for (i=; i < displaySize / sizeof(unsigned int); i++) {
            buf[i] = UYVY_BLACK;
        }

        /* Translate the virtual address to physical as resizer needs this */
        physDisplays[bufIdx] = Memory_getPhysicalAddress(virtDisplays[bufIdx]);
        DBG("virtDisplays[%d] LA:%#lx PA:%#lx\n",
            bufIdx, (unsigned long) virtDisplays[bufIdx], physDisplays[bufIdx]);
    }
           

可以看到YUV422存储顺序为Y Cr Y Cb Y Cr Y Cb Y Cr Y Cb……，Y是全部保留，而Cr，Cb则是在一行中交替采样，而不像YUV420，一行采样 Cb，下一行采用Cr。注意区别。

再说一下上面YCbCr的由来，是通过RGB转化的，具体代码如下：

RGB -> YCbCr代码
void rgb2ycbcr(unsigned char r,unsigned char g,unsigned char b)
{
    unsigned char ycbcr_res[]; 
    ycbcr_res[]= (unsigned char)(r *  + g *  + b * )+ ;   
    ycbcr_res[]= (unsigned char)(r *- + g * - + b * )+ ;  
    ycbcr_res[]= (unsigned char)(r *  + g * - + b *-)+ ;
}
           

代码测试