如何在Windows Phone 8上從視頻文件（.mp4）創建縮略圖？

Question

我已經使用AudioVideoCapture設計來錄製視頻，但我無法獲得錄製視頻的縮略圖。請幫幫我！

Answer 1

你可以試試這個。如果您使用AudioVideoCaptureDevice api。在每次捕獲幀後調用事件（previewThumbnail）。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(); 
     } 
    } 
}