CMSampleBufferRef 转换为UIImage

步骤：CMSampleBufferRef --->CVImageBufferRef--->CGImageRef--->UIImage

• (UIImage *)convertSampleBufferToImage:(CMSampleBufferRef)sampleBuffer
  {
  //制作 CVImageBufferRef
  CVImageBufferRef buffer;
  buffer = CMSampleBufferGetImageBuffer(sampleBuffer);

  CVPixelBufferLockBaseAddress(buffer, 0);

  //从 CVImageBufferRef 取得影像的细部信息
  uint8_t *base;
  size_t width, height, bytesPerRow;
  base = CVPixelBufferGetBaseAddress(buffer);
  width = CVPixelBufferGetWidth(buffer);
  height = CVPixelBufferGetHeight(buffer);
  bytesPerRow = CVPixelBufferGetBytesPerRow(buffer);

  //利用取得影像细部信息格式化 CGContextRef
  CGColorSpaceRef colorSpace;
  CGContextRef cgContext;
  colorSpace = CGColorSpaceCreateDeviceRGB();
  cgContext = CGBitmapContextCreate(base, width, height, 8, bytesPerRow, colorSpace, kCGBitmapByteOrder32Little | kCGImageAlphaPremultipliedFirst);
  CGColorSpaceRelease(colorSpace);

  //透过 CGImageRef 将 CGContextRef 转换成 UIImage
  CGImageRef cgImage;
  UIImage *image;
  cgImage = CGBitmapContextCreateImage(cgContext);
  image = [UIImage imageWithCGImage:cgImage];
  CGImageRelease(cgImage);
  CGContextRelease(cgContext);

  CVPixelBufferUnlockBaseAddress(buffer, 0);

  return image;
  }