Question

我似乎无法找到MediaCapture类的属性，它允许我检测前置摄像头并切换到它（如果可用）。这是我当前设备的设置，它在Windows（前凸轮）和电话（后凸轮）上按预期工作。没有一个Microsoft示例显示前置摄像头在Universal或WP 8.1（WinRT / Jupiter）中使用。

mediaCaptureManager = new MediaCapture();
            await mediaCaptureManager.InitializeAsync();

            if (mediaCaptureManager.MediaCaptureSettings.VideoDeviceId != "" && mediaCaptureManager.MediaCaptureSettings.AudioDeviceId != "")
            {
                StartStopRecordingButton.IsEnabled = true;
                TakePhotoButton.IsEnabled = true;

                ShowStatusMessage("device initialized successfully!");
                mediaCaptureManager.VideoDeviceController.PrimaryUse = CaptureUse.Video;
                mediaCaptureManager.SetPreviewRotation(VideoRotation.Clockwise90Degrees);
                mediaCaptureManager.SetRecordRotation(VideoRotation.Clockwise90Degrees);
                mediaCaptureManager.RecordLimitationExceeded += RecordLimitationExceeded;
                mediaCaptureManager.Failed += Failed;
            }

Answer 1

以下是如何获取设备的可用摄像头并为流设置前置摄像头：

                mediaCaptureManager = new MediaCapture();
            var devices = await DeviceInformation.FindAllAsync(DeviceClass.VideoCapture);
            var deviceInfo = devices[0]; //grab first result

            foreach (var device in devices)
            {
                if (device.Name.ToLowerInvariant().Contains("front"))
                {
                    deviceInfo = frontCamera = device;
                    hasFrontCamera = true;
                }
                if (device.Name.ToLowerInvariant().Contains("back"))
                {
                    rearCamera = device;
                }
            }

            var mediaSettings = new MediaCaptureInitializationSettings
            {
                MediaCategory = MediaCategory.Communications,
                StreamingCaptureMode = StreamingCaptureMode.AudioAndVideo,
                VideoDeviceId = deviceInfo.Id
            };

            await mediaCaptureManager.InitializeAsync(mediaSettings);

您需要考虑旋转，因为不同设备上的前置和后置摄像头具有不同的旋转，但这会正确初始化您的MediaCapture

Answer 2

Microsoft github页面上有一个相关的示例，尽管它们的目标是Windows 10.但是，API应该适用于8 / 8.1。

UniversalCameraSample：此照片会捕捉照片，并支持纵向和横向方向。以下是相关部分：

private static async Task<DeviceInformation> FindCameraDeviceByPanelAsync(Windows.Devices.Enumeration.Panel desiredPanel)
{
    // Get available devices for capturing pictures
    var allVideoDevices = await DeviceInformation.FindAllAsync(DeviceClass.VideoCapture);

    // Get the desired camera by panel
    DeviceInformation desiredDevice = allVideoDevices.FirstOrDefault(x => x.EnclosureLocation != null && x.EnclosureLocation.Panel == desiredPanel);

    // If there is no device mounted on the desired panel, return the first device found
    return desiredDevice ?? allVideoDevices.FirstOrDefault();
}

你可以像这样使用它：

// Attempt to get the front camera if one is available, but use any camera device if not
var cameraDevice = await FindCameraDeviceByPanelAsync(Windows.Devices.Enumeration.Panel.Front);

if (cameraDevice == null)
{
    Debug.WriteLine("No camera device found!");
    return;
}

// Create MediaCapture and its settings
_mediaCapture = new MediaCapture();

var settings = new MediaCaptureInitializationSettings { VideoDeviceId = cameraDevice.Id };

// Initialize MediaCapture
try
{
    await _mediaCapture.InitializeAsync(settings);
    _isInitialized = true;
}
catch (UnauthorizedAccessException)
{
    Debug.WriteLine("The app was denied access to the camera");
}
catch (Exception ex)
{
    Debug.WriteLine("Exception when initializing MediaCapture with {0}: {1}", cameraDevice.Id, ex.ToString());
}

仔细查看示例，了解如何获取所有详细信息。或者，要进行演练，您可以观看最近//版本/会议中的camera session，其中包括一些相机示例的演练。

如何在Windows Phone 8.1（WinRT / Jupiter）中切换到前置摄像头

2 个答案: