How to tell whether video preview is working?

Question

An app shows video preview with code essentially the same as in
the MSDN document:
async void ShowPreview(object sender, RoutedEventArgs e)
if (mediaCaptureMgr == null)
// Using Windows.Media.Capture.MediaCapture APIs
// to stream from webcam
mediaCaptureMgr = new MediaCapture();
await mediaCaptureMgr.InitializeAsync();
myCaptureElement.Source = mediaCaptureMgr;
await mediaCaptureMgr.StartPreviewAsync();
It works most of the time. However, sometimes the video does not show. When this happens, myCaptureElement.ActualWidth and myCaptureElement.ActualHeight still return the correct values. This probably means at least something is working. In this case, how can
the code tell what my eyes can see - the video is not showing?
Hong

Answer 1

Hi Hong,
Based on my knowledge, your problem may related to the dispose of the MediaCapture object. Forget to dispose it when app suspends will result in a negative user experience for your app.
About your question, I’ve not seen such property in MediaCapture class, so it’s recommend to create a Boolean that indicate whether the app is currently previewing video. You need to maintain this object when start or stop preview. You can find more information
from this page.
https://msdn.microsoft.com/en-us/library/windows/apps/xaml/hh868171.aspx. See Step 5 section.
Regards,
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