将CMSampleBufferRef转换为OpenCV IplImage的最佳/最快方法是什么？

Question

我正在编写一个iPhone应用程序,可以使用OpenCV进行某种实时图像检测.什么是一个转换的最佳途径CMSampleBufferRef图像从相机(我使用AVCaptureVideoDataOutputSampleBufferDelegateAVFoundation的)到IplImage该OpenCV的理解？转换需要足够快,以便可以实时运行.

- (void)captureOutput:(AVCaptureOutput *)captureOutput
    didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer
    fromConnection:(AVCaptureConnection *)connection
{
  NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];

  // Convert CMSampleBufferRef into IplImage
  IplImage *openCVImage = ???(sampleBuffer);

  // Do OpenCV computations realtime
  // ...

  [pool release];
} 

提前致谢.

Answer 1

此示例代码基于Apple的样本来管理CMSampleBuffer的指针:

- (IplImage *)createIplImageFromSampleBuffer:(CMSampleBufferRef)sampleBuffer {
    IplImage *iplimage = 0;
    if (sampleBuffer) {
        CVImageBufferRef imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer);
        CVPixelBufferLockBaseAddress(imageBuffer, 0);

        // get information of the image in the buffer
        uint8_t *bufferBaseAddress = (uint8_t *)CVPixelBufferGetBaseAddressOfPlane(imageBuffer, 0);
        size_t bufferWidth = CVPixelBufferGetWidth(imageBuffer);
        size_t bufferHeight = CVPixelBufferGetHeight(imageBuffer);

        // create IplImage
        if (bufferBaseAddress) {
            iplimage = cvCreateImage(cvSize(bufferWidth, bufferHeight), IPL_DEPTH_8U, 4);
            iplimage->imageData = (char*)bufferBaseAddress;
        }

        // release memory
        CVPixelBufferUnlockBaseAddress(imageBuffer, 0);
    }
    else
        DLog(@"No sampleBuffer!!");

    return iplimage;
}

您需要创建一个4通道IplImage,因为Phone的相机缓冲区位于BGRA中.

根据我的经验,这种转换足够快,可以在实时应用程序中完成,但当然,任何添加到它的内容都会花费时间,特别是对于OpenCV.