如何在 Windows 10 通用应用程序中切换到后置摄像头

Question

我似乎找不到 MediaCapture 类的属性，该属性允许我检测 Surface 中的后置和前置摄像头，并在 Combobox 项可用时切换到它。这是我当前的设备设置。

        mc = new MediaCapture();
        DeviceInformationCollection devices = await DeviceInformation.FindAllAsync(DeviceClass.VideoCapture);

        // Use the front camera if found one
        if (devices == null) return;
        var info = devices[0];

        //var rearCamera;
        //DeviceInformation info2 = devices[1];

        foreach (var devInfo in devices)
        {
            if (devInfo.Name.ToLowerInvariant().Contains("front"))
            {

                info = devInfo;
                //info2 = devInfo;
                //frontCam = true;
                //backCam = true;
                camera = true;
                //continue;
            }
            if (devInfo.Name.ToLowerInvariant().Contains("back"))
            {
                var rearCamera = devices[1];
                rearCamera = devInfo;
            }
        }

        await mc.InitializeAsync(new MediaCaptureInitializationSettings
            {
            MediaCategory = MediaCategory.Communications,
            StreamingCaptureMode = StreamingCaptureMode.AudioAndVideo,
            VideoDeviceId = info.Id,
                //VideoDeviceId = info2.Id
            });


        DisplayInformation displayInfo = DisplayInformation.GetForCurrentView();
        displayInfo.OrientationChanged += DisplayInfo_OrientationChanged;
        DisplayInfo_OrientationChanged(displayInfo, null);

        stream = new InMemoryRandomAccessStream();
        llmr = await mc.PrepareLowLagRecordToStreamAsync(MediaEncodingProfile.CreateMp4(VideoEncodingQuality.Auto), stream);
        await llmr.StartAsync();
        await llmr.StopAsync();


        CaptureElement.Source = mc;
        CaptureElement.FlowDirection = camera ? FlowDirection.RightToLeft : FlowDirection.LeftToRight;
        CaptureStack.Visibility = Visibility.Visible;
        CameraErrorTextBlock.Visibility = Visibility.Collapsed;
        RecordProgress.Visibility = Visibility.Visible;
        CaptureGrid.Visibility = Visibility.Visible;
        CancelButton.HorizontalAlignment = HorizontalAlignment.Right;
        //CaptureElement.FlowDirection = FlowDirection.LeftToRight;

        // prepare low lag recording
        stream = new InMemoryRandomAccessStream();
        llmr = await mc.PrepareLowLagRecordToStreamAsync(MediaEncodingProfile.CreateMp4(VideoEncodingQuality.Auto), stream);



        await mc.StartPreviewAsync();

Answer 1

您需要使用所需相机设备（从 DeviceInformationCollection 设备获取）的 VideoDeviceId 再次运行 MediaCapture.InitializeAsync。然后将 CaptureElement.Source 设置为新的 MediaCapture。

var devices = await DeviceInformation.FindAllAsync(DeviceClass.VideoCapture);

if (devices.Count > 0)
            {
                if (devices.Count >= 2)
                {
                    var device = devices.FirstOrDefault(d => d.EnclosureLocation.Panel == Windows.Devices.Enumeration.Panel.Front);
                }
            }


var frontVideoId = device.Id;
await mc.InitializeAsync(new MediaCaptureInitializationSettings
            {
            MediaCategory = MediaCategory.Communications,
            StreamingCaptureMode = StreamingCaptureMode.AudioAndVideo,
            VideoDeviceId = frontVideoId
            });
CaptureElement.Source = mc;
await mc.StartPreviewAsync();

Answer 2

您应该使用 DeviceInformation 的 "EnclosureLocation" 属性。

var allVideoDevices = await DeviceInformation.FindAllAsync(DeviceClass.VideoCapture);
// Get the desired camera by panel
DeviceInformation cameraDevice =
    allVideoDevices.FirstOrDefault(x => x.EnclosureLocation != null &&
    x.EnclosureLocation.Panel == Windows.Devices.Enumeration.Panel.Back);

Windows.Devices.Enumeration.Panel.Back 将是后置摄像头的 EnclosureLocation。