原文:Windows Phone 8.1 多媒体（2）：视频
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<MediaCapture> 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：链接
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;
}