如何将 CMSampleBuffer 转换为 std::vector<char>？

Question

我有来自 AVCaptureVideoDataOutputSampleBufferDelegate 方法的图像流：

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

然后我想获取 sampleBuffer 并将其提供给 C++ openalrp 库以识别哪个获取图像字节或原始像素数据。我应该使用什么函数以及如何将 sampleBuffer 转换为合适的输入类型，std::vector<char> 或 unsigned char* pixelData?

来自 alpr.h 文件：

  // Recognize from an image on disk
  AlprResults recognize(std::string filepath);

  // Recognize from byte data representing an encoded image (e.g., BMP, PNG, JPG, GIF etc).
  AlprResults recognize(std::vector<char> imageBytes);

  // Recognize from byte data representing an encoded image (e.g., BMP, PNG, JPG, GIF etc).
  AlprResults recognize(std::vector<char> imageBytes, std::vector<AlprRegionOfInterest> regionsOfInterest);

  // Recognize from raw pixel data.  
  AlprResults recognize(unsigned char* pixelData, int bytesPerPixel, int imgWidth, int imgHeight, std::vector<AlprRegionOfInterest> regionsOfInterest);

Answer 1

终于找到答案了：

CVPixelBufferRef imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer);
CVPixelBufferLockBaseAddress(imageBuffer, 0);
unsigned char *tempAddress = (unsigned char *)CVPixelBufferGetBaseAddress(imageBuffer);
size_t bytesPerRow = CVPixelBufferGetBytesPerRow(imageBuffer);
size_t width = CVPixelBufferGetWidth(imageBuffer);
size_t height = CVPixelBufferGetHeight(imageBuffer);
CVPixelBufferUnlockBaseAddress(imageBuffer, 0);

CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
CGContextRef newContext = CGBitmapContextCreate(tempAddress, width, height, 8, bytesPerRow, colorSpace, kCGBitmapByteOrder32Little | kCGImageAlphaPremultipliedFirst);
CGImageRef newImage = CGBitmapContextCreateImage(newContext);
CGContextRelease(newContext);
CGColorSpaceRelease(colorSpace);
UIImage *image = [UIImage imageWithCGImage:newImage];

NSData *data = UIImagePNGRepresentation(image);

if (data) {
    unsigned long int len = data.length;
    std::vector<char> v((char *)data.bytes, (char *)data.bytes + len);
    alpr::AlprResults results = delegate->recognize(v);
}

CGImageRelease(newImage);