如何獲取錄製視頻的縮略圖 - Windows Phone 8？

Question

我用CaptureSource()來錄製像這個主題How to record video in a camera app for Windows Phone一樣的視頻，但我無法獲得錄製視頻的縮略圖。

Answer 1

下面是解：

[...]

// Add eventhandlers for captureSource. 
captureSource.CaptureFailed += new EventHandler<ExceptionRoutedEventArgs>(OnCaptureFailed); 
captureSource.CaptureImageCompleted += captureSource_CaptureImageCompleted; 

[...]

captureSource.Start(); 
captureSource.CaptureImageAsync(); 

[...]

void captureSource_CaptureImageCompleted(object sender, CaptureImageCompletedEventArgs e) 
{ 
using (IsolatedStorageFile isoStore = IsolatedStorageFile.GetUserStoreForApplication()) 
    { 
    System.Windows.Media.Imaging.WriteableBitmap wb = e.Result; 

    string fileName = "CameraMovie.jpg"; 
    if (isoStore.FileExists(fileName)) 
     isoStore.DeleteFile(fileName); 

    IsolatedStorageFileStream file = isoStore.CreateFile(fileName); 

    System.Windows.Media.Imaging.Extensions.SaveJpeg(wb, file, wb.PixelWidth, wb.PixelHeight, 0, 85); 

    file.Close(); 
} 
} 

UPDATE：給用戶的可能性時，他想

在點擊事件的點擊事件viewfinderRectangle

<Rectangle 
    x:Name="viewfinderRectangle" 
    [...] 
    Tap="viewfinderRectangle_Tap" /> 

呼叫captureSource.CaptureImageAsync();添加拿縮略圖

private void viewfinderRectangle_Tap(object sender, System.Windows.Input.GestureEventArgs e) 
{ 
captureSource.CaptureImageAsync(); 
} 

Answer 2

你可以試試這個。如果您使用AudioVideoCaptureDevice api。以下事件在每幀捕獲後調用。您可以選擇任何您需要的框架。作爲第一個。

private AudioVideoCaptureDevice VideoRecordingDevice; 
VideoRecordingDevice.PreviewFrameAvailable += previewThumbnail; 
bool DisablePreviewFrame = false; 

private void previewThumbnail(ICameraCaptureDevice a, object b) 
{ 
    if (!DisablePreviewFrame) 
    { 
     DisablePreviewFrame = true; 
     int frameWidth = (int)VideoRecordingDevice.PreviewResolution.Width; 
     int frameHeight = (int)VideoRecordingDevice.PreviewResolution.Height; 
    } 
    int[] buf = new int[frameWidth * frameHeight]; 
    VideoRecordingDevice.GetPreviewBufferArgb(buf); 
    using (IsolatedStorageFile isoStoreFile = IsolatedStorageFile.GetUserStoreForApplication()) 
    { 
     var fileName = "temp.jpg"; 

     if (isoStoreFile.FileExists(fileName)) 
      isoStoreFile.DeleteFile(fileName); 
     using (IsolatedStorageFileStream isostream = isoStoreFile.CreateFile(fileName)) 
     { 
      WriteableBitmap wb = new WriteableBitmap(frameWidth, frameWidth); 
      Array.Copy(buf, wb.Pixels, buf.Length); 
      wb.SaveJpeg(isostream, 120, 120, 0, 60); 
      isostream.Close(); 
     } 
    } 
}