CaptureSource.Start（）在Windows Phone Silverlight 8.1中引發System.UnauthorizedAccessException Silverlight 8.1

Question

我在使用Windows Phone Silverlight 8.1應用程序中的相機時遇到問題。我只想初始化相機並查看其預覽（現在我不需要任何照片或視頻捕捉）。我發現nice and simple example on MSDN和

private CaptureSource captureSource; 
private VideoCaptureDevice videoCaptureDevice; 

private void InitializeVideoRecorder() 
{ 
    try 
    { 
     if (captureSource == null) 
     { 
      captureSource = new CaptureSource(); 
      var a = captureSource.VideoCaptureDevice; 

      videoCaptureDevice = CaptureDeviceConfiguration.GetDefaultVideoCaptureDevice(); 

      captureSource.CaptureFailed += OnCaptureFailed; 

      if (videoCaptureDevice != null) 
      { 
       VideoRecorderBrush = new VideoBrush(); 
       VideoRecorderBrush.SetSource(captureSource); 

       captureSource.Start(); 
       CameraStatus = "Tap record to start recording..."; 
      } 
      else 
      { 
       CameraStatus = "A camera is not supported on this phone."; 
      } 
     } 
    } 
    catch (Exception ex) 
    { 
     CameraStatus = "ERROR: " + ex.Message.ToString(); 
    } 
} 

代碼停在captureSource.Start();扔System.UnauthorizedAccessException: Attempted to perform an unauthorized operation.。

首先，我發現在'WMAppManifest.xml'中需要ID_CAP_ISV_CAMERA功能的信息（在同一頁上）。但我有問題，將它添加，這是因爲：

1. 我無法找到設計師這種能力
2. 我得到的錯誤，當我將其添加到manualy .xml文件

錯誤重現如下：

Warning 1 The 'Name' attribute is invalid - The value 'ID_CAP_ISV_CAMERA' is invalid according to its datatype 'http://schemas.microsoft.com/appx/2010/manifest:ST_Capabilities' - The Enumeration constraint failed. 
Error 3 App manifest validation failed. Value 'ID_CAP_ISV_CAMERA' of attribute '/Package/Capabilities/Capability/@Name' must be a valid capability. 

我甚至找到了相同的解決方案SO WP8.1 SilverLight Microsoft.Devices.PhotoCamera Access Denied

有人可以告訴我爲什麼我不能使用原始MSDN解決方案來解決這個問題？

Answer 1

首先，它看起來像是試圖將該功能添加到Package.appxmanifest而不是WMAppManifest.xml。你應該能夠找到WMAppManifest.xml下，解決方案管理器 - > <項目> - >屬性：

打開該文件應該給你加ID_CAP_*功能的選項。

其次，你需要指定都ID_CAP_ISV_CAMERA和ID_CAP_MICROPHONE爲了使用CaptureSource.Start()，即使你只使用的設備之一。