YUV420切割（抠图）

原文地址：https://blog.51cto.com/cto521/1586190

int cut_yuv420P(uint8_t *pInBuf, int width, int height, uint8_t **pOutBuf, int new_x, int new_y, int new_width, int new_height)
{
    if(NULL == pInBuf || 0 == width || 0 == height)
        return -1;

    int length = new_width* new_height* 3 / 2;
    *pOutBuf = (uint8_t *)malloc(length);
    if (NULL == *pOutBuf)
    {
        printf("malloc new size memory failed! size=%d\n", length);
        return -1;
    }
    memset(*pOutBuf , 0, length);

    uint8_t *pUBuf = *pOutBuf + new_width * new_height;
    uint8_t *pVBuf = *pOutBuf +new_width * new_height * 5 / 4;
    for(int x = 0; x < new_width; x++)
    {
        for (int y = 0; y < new_height; y++)    //每个循环写一列
        {
            *(*pOutBuf + y * new_width + x) = *(pInBuf + (x + new_x) + width * (y + new_y));    //cope Y
            int ret = (y + new_y)%2;
            if (1 == (x + new_x)%2 && 1 == (y + new_y)%2)
            {
                long pix = width * height + (width>>1) * ((y + new_y)>>1) + (((x + new_x))>>1);
                *(pUBuf + (new_width/2)*(y/2) + x/2) = *(pInBuf + pix); //cope U

                pix += width * height / 4;
                *(pVBuf + (new_width/2)*(y/2) + x/2) = *(pInBuf + pix); //cope V
            }
        }
    }   
    return 0;
}