YUV圖片旋轉

1、從H264視頻流中解析出來的圖片格式是YUV

　　YUV旋轉可以選擇手工旋轉，也可以利用libYUV，libYUV開啟NEON指令之后可以加快處理速度

　　在iOS系統上，利用Accelcerate庫進行加速，其中旋轉的方法是libYUV旋轉的20倍

　　

    //測試YUV to RGBA 旋轉然后 再到YUV 性能
    
    int width  = inFrame->width;
    int height = inFrame->height;
    int size   = width*height*4;
    uint8 *pRGBA = (uint8 *)calloc(size*3, sizeof(uint8));
    uint8 *pDstRGBA = (uint8 *)calloc(size*3, sizeof(uint8));
    
    start = [NSDate date];
    
    libyuv::I420ToARGB(inFrame->data[0],
                       inFrame->linesize[0],
                       inFrame->data[1],
                       inFrame->linesize[1],
                       inFrame->data[2],
                       inFrame->linesize[2],
                       pRGBA,
                       width*4,
                       width,
                       height);
    
    Pixel_8888 bgColor = {0,0,0,0};
    vImageRotate_ARGB8888((const vImage_Buffer *)pRGBA,
                          (const vImage_Buffer *)pDstRGBA,
                          NULL,
                          angle,
                          bgColor,
                          kvImageBackgroundColorFill);
    
    libyuv::ARGBToI420(pDstRGBA,
                       height*4,
                       _rotFrame->data[0],
                       _rotFrame->linesize[0],
                       _rotFrame->data[1],
                       _rotFrame->linesize[1],
                       _rotFrame->data[2],
                       _rotFrame->linesize[2],
                       width,
                       height);
    
    LOGE("YUV Rotate -[vImageRotate_ARGB8888] cost : %f", [[NSDate date] timeIntervalSinceDate:start]);

    free(pRGBA);
    free(pDstRGBA);