StackOverflow2013

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copied!<p>In Windows Phone 7.0 it wasn't possible using the "official" SDK to access the camera other than using <a href="http://msdn.microsoft.com/en-us/library/windowsphone/develop/microsoft.phone.tasks.cameracapturetask%28v=vs.105%29.aspx" rel="nofollow noreferrer">CameraCaptureTask</a>. But using <code>Microsoft.Phone.InteropServices</code> library it was possible to create a custom camera view in the application. If you used this <code>VideoCamera</code> class, it had an event called <code>ThumbnailSavedToDisk</code>, which might be what you have heard about. But apps using <code>Microsoft.Phone.InteropServices</code> was never allowed in the Windows Phone Marketplace. You can read more <a href="http://dotnet.dzone.com/articles/how-videocameracamera-content" rel="nofollow noreferrer">about it here</a>.</p> <hr> <p>To generate a thumbnail from a video file one solution would be to read up on how the MP4 file format works and extract one of the frames and use that as a thumbnail. Unfortunatly I haven't found any libraries that can do this.</p> <p>Another, but far from optimal solution, would be to play the video in a MediaElement and then render that Control to a bitmap. This can be done with the following code (written in XAML/C#, I don't know VB.net, but should be easy to port):</p> <pre class="lang-xml prettyprint-override"><code><MediaElement x:Name="VideoPlayer" Width="640" Height="480" AutoPlay="True" RenderTransformOrigin="0.5, 0.5" VerticalAlignment="Center" HorizontalAlignment="Center" Stretch="Fill" Canvas.Left="80"/> </code></pre> <p>And then to create the thumbnail:</p> <pre><code>// Set an event handler for when video has loaded VideoPlayer.MediaOpened += VideoPlayer_MediaOpened; // Read video from storage IsolatedStorageFileStream videoFile = new IsolatedStorageFileStream("MyVideo.mp4", FileMode.Open, FileAccess.Read, IsolatedStorageFile.GetUserStoreForApplication()); VideoPlayer.SetSource(videoFile); // Start playback VideoPlayer.Play(); </code></pre> <p>And then create the event handler which "captures" the thumbnail:</p> <pre><code>void VideoPlayer_MediaOpened(object sender, RoutedEventArgs e) { Thread.Sleep(100); // Wait for a short time to avoid black frame WriteableBitmap wb = new WriteableBitmap(VideoPlayer, new TranslateTransform()); thumbnailImageHolder.Source = wb; // Setting it to a Image in the XAML code to see it VideoPlayer.Stop(); } </code></pre> <p>Here is how it looks when using a modified version of the <a href="http://code.msdn.microsoft.com/wpapps/Video-Recorder-Sample-5e800bbf" rel="nofollow noreferrer">Video Recorder Sample</a>. (The small image with the blue border in the upper right corner is the thumbnail of the recorded video. Behind is the camera Viewer.)</p> <p><img src="https://i.stack.imgur.com/lpz8n.png" alt="enter image description here"></p>

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