摄像头NV21格式转RGB的JAVA代码，测试正确

　　摄像头数据出来是NV21，转换为RGB。测试时发现性能很差：

    static int depth = 4;

    public static void NV21ToRGBA(byte[] input, int width, int height, byte[] output, boolean isRGB)
    {
        int nvOff = width * height ;
        int  i, j, yIndex = 0;
        int y, u, v;
        int r, g, b, nvIndex = 0;
        for(i = 0; i < height; i++){
            for(j = 0; j < width; j ++,++yIndex){
                nvIndex = (i / 2)  * width + j - j % 2;
                y = input[yIndex] & 0xff;
                u = input[nvOff + nvIndex ] & 0xff;
                v = input[nvOff + nvIndex + 1] & 0xff;

                // yuv to rgb
                r = y + ((351 * (v-128))>>8);  //r
                g = y - ((179 * (v-128) + 86 * (u-128))>>8); //g
                b = y + ((443 * (u-128))>>8); //b
                
                r = ((r>255) ?255 :(r255) ?255 :(g255) ?255 :(b