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Can't get a spectator view if an app uses MediaCapture to also grab hololens camera image?

edited October 2018 in Troubleshooting

My App is based on the FaceTag app sample available here : https://github.com/PacktPublishing/Microsoft-HoloLens-By-Example/tree/master/Chapter2/Complete/FaceTag

That C# application uses the MediaCapture class (Windows.Media.Capture) which regularly sends back images from the hololens front camera. My app analyses that image to add holograms and informations for the hololens wearer.

I wanted to show a collegue the result we currently have using my remote PC and the Hololens Device Portal (in the Views \ Mixed Reality Capture menu).
The Device Portal Live preview works great when my app is not started: I can see on my PC whatever I see in as Hololens wearer BUT when I start my app one of the two following things happens:

  • If the Live Preview is started before my app, then my app never retrieves any image from the MediaCapture class, so I can't process any image, so I can't display any Holograms.
  • If the Live Preview is started after my app, then my app works great BUT the LivePreview never starts, so I can't show anything to my collegue.

The obvious problem is that both processes want to use the Hololens webcam so the "First to ask, First to get" rules apply but my question is :

Is there a way to make both processes share the webcam feed ? If not, how will I be able to show my app without having to make a room full of people wear them one at a time ?


  • Hi nrenaud,
    I am having a similar issue. I also have an app where camera uses MediaCapture class and hence I am not able to start mixed reality capture from HoloLens Web Portal. Did you manage to find a solution?

  • nrenaudnrenaud
    edited April 2019

    @Holoholic : Sorry for the late answer : the short answer is no, I did not successfully succeed to display the spectator view while using the camera of the Hololens.

    BUT I found a solution (not the expected one but one that was acceptable) : I was able to record a video of the spectator view if FIRST, I started my app and let it grab the camera and THEN I used the bloom gesture to make the menu appear and pressed the "Start Recording a Video" event. When I had enough video material, I used the bloom gesture to stop the video capture.

    CAUTION though, the recorded video quality is not up to the real live display quality.

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