YUV图片旋转

1、从H264视频流中解析出来的图片格式是YUV

　　YUV旋转可以选择手工旋转，也可以利用libYUV，libYUV开启NEON指令之后可以加快处理速度

　　在iOS系统上，利用Accelcerate库进行加速，其中旋转的方法是libYUV旋转的20倍

//测试YUV to RGBA 旋转然后 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);