UVC usb摄像头YUV422数据转NV21

void yuyv_to_nv21(char * image_in, char* image_out, int width, int height, unsigned long int filesize)
{
     
    int pixNUM = width * height;
    unsigned int cycleNum = filesize /pixNUM/2;
    printf("cycleNUM = %d\n",cycleNum);

     
    char *y = image_out;
    char *uv = image_out + pixNUM ;

    char *start = image_in;
    unsigned int i =0;
    int j =0,k =0;

     
    for(i= 0; i