//CMSampleBufferRef=>UIImage
- (UIImage *)sampleBufferRefConvertToImage:(CMSampleBufferRef)sampleBuffer
{
  
    if (!CMSampleBufferIsValid(sampleBuffer)) {
        return nil;
    }
    CVImageBufferRef  imageBufferRef = CMSampleBufferGetImageBuffer(sampleBuffer);
    CIImage *ciImage = [CIImage imageWithCVImageBuffer:imageBufferRef];
    if (!ciImage) {
        return nil;
    }
    UIImage *image = [UIImage imageWithCIImage:ciImage];
    return image;
}