Question

我需要获取当前预览帧分辨率才能正确显示检测到的面部边界：

 _mediaCapture = new MediaCapture();
 await _mediaCapture.InitializeAsync();
 var definition = new FaceDetectionEffectDefinition();
 var faceDetectionEffect = (FaceDetectionEffect)await _mediaCapture.AddVideoEffectAsync(definition, MediaStreamType.VideoPreview);
 faceDetectionEffect.DesiredDetectionInterval = TimeSpan.FromMilliseconds(33);
 faceDetectionEffect.Enabled = true;
 faceDetectionEffect.FaceDetected += FaceDetected;
 PreviewControl.Source = _mediaCapture;
 await _mediaCapture.StartPreviewAsync();

 private async void FaceDetected(object sender, FaceDetectedEventArgs args)
 {
     double scale = PreviewControl.ActualWidth / ???;
     await Dispatcher.RunAsync(Windows.UI.Core.CoreDispatcherPriority.High, () =>
     {

         var faces = args.ResultFrame.DetectedFaces;
         for (int i = 0; i < faces.Count; i++)
         {
             double scale = P
             var faceRect = faces[i].FaceBox;
             Rectangle item;
             if (FacesCanvas.Children.Count <= i)
             {
                 item = new Rectangle();
                 item.Fill = new SolidColorBrush(Colors.AliceBlue);
                 FacesCanvas.Children.Add(item);
             }
             else item = (Rectangle)FacesCanvas.Children[i];
             item.Height = faceRect.Height * scale;
             item.Width = faceRect.Width * scale;
             Canvas.SetLeft(item, faceRect.X * scale);
             Canvas.SetTop(item, faceRect.Y * scale);
         }
     });
 }

Answer 1

好的，我明白了：

var props = (VideoEncodingProperties) _mediaCapture.VideoDeviceController
    .GetMediaStreamProperties(MediaStreamType.VideoPreview);

double scale = PreviewControl.ActualWidth / props.Width;

源： https://github.com/Microsoft/Windows-universal-samples/blob/master/Samples/CameraFaceDetection/cs/MainPage.xaml.cs

如何获取MediaCapture的当前预览帧分辨率

1 个答案: