Windows Phone 8.1 多媒体（2）：视频
（1）拍摄视频
拍摄视频和拍摄相片的方法是基本一致的：
MediaCapture mediaCapture;MediaEncodingProfile videoEncodingProperties;protected override async void OnNavigatedTo(NavigationEventArgs e){ HardwareButtons.CameraHalfPressed += HardwareButtons_CameraHalfPressed; HardwareButtons.CameraReleased += HardwareButtons_CameraReleased; videoCaptrueElement.Source = await Initialize(); await mediaCapture.StartPreviewAsync();}async void HardwareButtons_CameraHalfPressed(object sender, CameraEventArgs e){ if( mediaCapture != null ) { var video = await KnownFolders.VideosLibrary.CreateFileAsync("video.mp4", CreationCollisionOption.GenerateUniqueName);await mediaCapture.StartRecordToStorageFileAsync(videoEncodingProperties, video); }}async void HardwareButtons_CameraReleased(object sender, CameraEventArgs e){ if( mediaCapture != null ) { await mediaCapture.StopRecordAsync(); }}private async Task Initialize(){ mediaCapture = new MediaCapture(); await mediaCapture.InitializeAsync(); mediaCapture.VideoDeviceController.PrimaryUse = CaptureUse.Video; videoEncodingProperties = MediaEncodingProfile.CreateMp4(VideoEncodingQuality.Vga); return mediaCapture;}protected override void OnNavigatedFrom(NavigationEventArgs e){ if( mediaCapture != null ) { mediaCapture.Dispose(); mediaCapture = null; }}
（2）编辑视频
视频编辑的 API 在 Windows.Media.Editing 命名空间下，具体可看 MSDN：
简单的说就是把某些视频实例化为 MediaClip，然后将这些视频添加到 MediaComposition.Clips 中去，最后将这些视频拼接到一起或添加个 BackgroundAudioTrack 什么的：
MediaClip video = await MediaClip.CreateFromFileAsync( await StorageFile.GetFileFromApplicationUriAsync(new Uri("ms-appx:///thanks.mp4")));MediaComposition videos = new MediaComposition();videos.Clips.Add(video);BackgroundAudioTrack bgm = await BackgroundAudioTrack.CreateFromFileAsync( await StorageFile.GetFileFromApplicationUriAsync(new Uri("Above Your Hand.mp3")));videos.BackgroundAudioTracks.Clear();videos.BackgroundAudioTracks.Add(bgm);await videos.SaveAsync(await ApplicationData.Current.LocalFolder.CreateFileAsync("video.mp4", CreationCollisionOption.ReplaceExisting));
（3）录制手机屏幕视频
录制手机屏幕视频是 WP8.1 新加的 API，使用方法和拍摄视频差不多，只需将录制对象设为屏幕即可：
var screenCapture = ScreenCapture.GetForCurrentView();mediaCapture = new MediaCapture();await mediaCapture.InitializeAsync(new MediaCaptureInitializationSettings{ VideoSource = screenCapture.VideoSource, AudioSource = screenCapture.AudioSource,});var file = await KnownFolders.VideosLibrary.CreateFileAsync("screenrecording.mp4", CreationCollisionOption.ReplaceExisting);await mediaCapture.StartRecordToStorageFileAsync(MediaEncodingProfile.CreateMp4(VideoEncodingQuality.Auto), file); 停止录制：
if( mediaCapture != null ){ await mediaCapture.StopRecordAsync(); mediaCapture.Dispose(); mediaCapture = null;}