Question

我正在使用AVCaptureVideoDataOutputSampleBufferDelegate使用以下委托方法在自定义UIView中显示来自iPhone相机的视频。

- (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection *)connection

我希望能够从图像中提取一些有用的信息，例如曝光，颜色，阈值。

访问此类信息的最佳方式是什么？

Answer 1

从示例缓冲区中提取元数据附件。您可以在其元数据中找到曝光，颜色等。像这样的东西：

NSDictionary *exifDictionary = (NSDictionary*)CMGetAttachment(sampleBuffer, kCGImagePropertyExifDictionary, NULL);

Answer 2

您可以使用以下代码访问基础像素数据：

CVPixelBufferRef pixelBuffer = CMSampleBufferGetImageBuffer(sampleBuffer);
CVReturn lock = CVPixelBufferLockBaseAddress(pixelBuffer, 0);
if (lock == kCVReturnSuccess) {
  int w = 0;
  int h = 0;
  int r = 0;
  int bytesPerPixel = 0;
  unsigned char *buffer;      

  if (CVPixelBufferIsPlanar(pixelBuffer)) {
    w = CVPixelBufferGetWidthOfPlane(pixelBuffer, 0);
    h = CVPixelBufferGetHeightOfPlane(pixelBuffer, 0);
    r = CVPixelBufferGetBytesPerRowOfPlane(pixelBuffer, 0);
    bytesPerPixel = r/w;

    buffer = CVPixelBufferGetBaseAddressOfPlane(pixelBuffer, 0);
  }else {
    w = CVPixelBufferGetWidth(pixelBuffer);
    h = CVPixelBufferGetHeight(pixelBuffer);
    r = CVPixelBufferGetBytesPerRow(pixelBuffer);
    bytesPerPixel = r/w;

    buffer = CVPixelBufferGetBaseAddress(pixelBuffer);
  }
}

我可以从相机中获取任何有用的信息吗？

2 个答案: