录制/捕获当前播放的音频

Question

我想在 UWP 或 Windows Phone 8.1 中捕获/记录当前播放的音频，“MEE dj”UWP 应用程序在其应用程序中完成相同的操作，该应用程序能够捕获应用程序中当前正在播放的音频。 请知道的人分享你的答案。

Answer 1

如何设置输入节点播放音乐而不是麦克风

Windows.Media.Audio namespace 包含AudioDeviceInputNode,AudioDeviceOutputNode,AudioFileInputNode,AudioFileOutputNode 等等。输入的麦克风是AudioDeviceInputNode，但播放音乐文件需要使用AudioFileInputNode。

好的，但是我怎样才能捕获该音频并将其保存到存储中

如上所述，为了保存到存储，我们需要使用AudioFileOutputNode。这是一个简单的演示，您可以加载一个文件进行录制，并从存储中选择一个文件来保存录制结果。代码如下：

XAML 代码

<StackPanel Background="{ThemeResource ApplicationPageBackgroundThemeBrush}" Padding="50">
    <TextBlock x:Name="txtresult" ></TextBlock>
    <Button x:Name="fileButton" Content="Load audio File for recording" Click="File_Click" MinWidth="120" MinHeight="45" Margin="0,20,0,0"/>
    <Button x:Name="OutpuyfileButton" Content="Load output File for save the recording result" Click="OutpuyfileButton_Click" MinWidth="120" MinHeight="45" Margin="0,20,0,0"/>
    <Button x:Name="graphButton" Content="Start playing" Click="Graph_Click" MinWidth="120" MinHeight="45" Margin="0,50,0,20"/>
    <Button x:Name="graphrecord" Content="Begin recording" Click="graphrecord_Click" ></Button>
</StackPanel>

后面的代码

  private AudioFileInputNode fileInput;
  private AudioFileOutputNode fileOutputNode;
  private AudioDeviceOutputNode deviceOutput;
  private AudioGraph graph;

  StorageFile outputfile;

  public MainPage()
  {
      this.InitializeComponent();
  }
  protected override async void OnNavigatedTo(NavigationEventArgs e)
  {
      await CreateAudioGraph();
  }
  private async Task CreateAudioGraph()
  {
      // Create an AudioGraph with default settings
      AudioGraphSettings settings = new AudioGraphSettings(AudioRenderCategory.Media);
      CreateAudioGraphResult result = await AudioGraph.CreateAsync(settings);
      if (result.Status != AudioGraphCreationStatus.Success)
      {
          // Cannot create graph
          await new MessageDialog(String.Format("AudioGraph Creation Error because {0}", result.Status.ToString())).ShowAsync();
          return;
      }
      graph = result.Graph;
      // Create a device output node
      CreateAudioDeviceOutputNodeResult deviceOutputNodeResult = await graph.CreateDeviceOutputNodeAsync();
      if (deviceOutputNodeResult.Status != AudioDeviceNodeCreationStatus.Success)
      {
          // Cannot create device output node
        txtresult.Text+="\n"+ String.Format("Device Output unavailable because {0}", deviceOutputNodeResult.Status.ToString());
          return;
      }
      deviceOutput = deviceOutputNodeResult.DeviceOutputNode;
      txtresult.Text += "\n" + "Device Output Node successfully created";
  }
  private async void File_Click(object sender, RoutedEventArgs e)
  {
      // If another file is already loaded into the FileInput node
      if (fileInput != null)
      {
          fileInput.Dispose();
      }
      FileOpenPicker filePicker = new FileOpenPicker();
      filePicker.SuggestedStartLocation = PickerLocationId.MusicLibrary;
      filePicker.FileTypeFilter.Add(".mp3");
      filePicker.FileTypeFilter.Add(".wav");
      filePicker.FileTypeFilter.Add(".wma");
      filePicker.FileTypeFilter.Add(".m4a");
      filePicker.ViewMode = PickerViewMode.Thumbnail;
      StorageFile file = await filePicker.PickSingleFileAsync();
      // File can be null if cancel is hit in the file picker
      if (file == null)
      {
          return;
      }
      CreateAudioFileInputNodeResult fileInputResult = await graph.CreateFileInputNodeAsync(file);
      if (AudioFileNodeCreationStatus.Success != fileInputResult.Status)
      {
          // Cannot read input file
          await new MessageDialog(String.Format("Cannot read input file because {0}", fileInputResult.Status.ToString())).ShowAsync();
          return;
      }

      fileInput = fileInputResult.FileInputNode;
      txtresult.Text += "\n" + "File load successfully,input nodes created";
  }

  private void Graph_Click(object sender, RoutedEventArgs e)
  {
      if (graphButton.Content.Equals("Start playing"))
      {
          fileInput.AddOutgoingConnection(deviceOutput);
          graph.Start();            
          graphButton.IsEnabled = false;
      }
  }

  private async void OutpuyfileButton_Click(object sender, RoutedEventArgs e)
  {
      FileSavePicker saveFilePicker = new FileSavePicker();
      saveFilePicker.FileTypeChoices.Add("Pulse Code Modulation", new List<string>() { ".wav" });
      saveFilePicker.FileTypeChoices.Add("Windows Media Audio", new List<string>() { ".wma" });
      saveFilePicker.FileTypeChoices.Add("MPEG Audio Layer-3", new List<string>() { ".mp3" });
      saveFilePicker.SuggestedFileName = "New Audio Track";
      outputfile = await saveFilePicker.PickSaveFileAsync();
      // File can be null if cancel is hit in the file picker
      if (outputfile == null)
      {
          return;
      }

      txtresult.Text +="\n"+ String.Format("Recording to {0}", outputfile.Name.ToString());
  }
  private MediaEncodingProfile CreateMediaEncodingProfile(StorageFile file)
  {
      switch (file.FileType.ToString().ToLowerInvariant())
      {
          case ".wma":
              return MediaEncodingProfile.CreateWma(AudioEncodingQuality.High);
          case ".mp3":
              return MediaEncodingProfile.CreateMp3(AudioEncodingQuality.High);
          case ".wav":
              return MediaEncodingProfile.CreateWav(AudioEncodingQuality.High);
          default:
              throw new ArgumentException();
      }
  }

  private async void graphrecord_Click(object sender, RoutedEventArgs e)
  {
      if (graphrecord.Content.Equals("Begin recording"))
      {
          MediaEncodingProfile fileProfile = CreateMediaEncodingProfile(outputfile);
          CreateAudioFileOutputNodeResult fileOutputNodeResult = await graph.CreateFileOutputNodeAsync(outputfile, fileProfile);
          if (fileOutputNodeResult.Status != AudioFileNodeCreationStatus.Success)
          {
              // FileOutputNode creation failed
              await new MessageDialog(String.Format("Cannot create output file because {0}", fileOutputNodeResult.Status.ToString())).ShowAsync();
              return;
          }
          fileOutputNode = fileOutputNodeResult.FileOutputNode;
          fileInput.AddOutgoingConnection(fileOutputNode);
          graphrecord.Content = "Stop recording";
      }
      else
      {
          graph.Stop();
          TranscodeFailureReason finalizeResult = await fileOutputNode.FinalizeAsync();
          if (finalizeResult != TranscodeFailureReason.None)
          {
              // Finalization of file failed. Check result code to see why
              await new MessageDialog(String.Format("Finalization of file failed because {0}", finalizeResult.ToString())).ShowAsync();
              return;
          }
          txtresult.Text += "\n" + "Recording completed";
          graphrecord.IsEnabled = false;
      }
  }

其他复杂的功能，还是参考官方示例吧。

Answer 2

您可以使用 Windows.Media.Audio 命名空间中的 API 为音频路由、混音和处理场景创建音频图。音频图的制作方法请参考this article。

音频图是一组相互连接的音频节点。您要录制的音频文件提供“音频输入节点”，“音频输出节点”是图形处理音频的目的地，音频可以从图形路由到目标音频文件。在“MeeDJ”windows store 应用程序中，它可以将两种音频混合并录制为一个。在这种情况下，我们可以使用“子混合节点”，从一个或多个节点获取音频并将它们组合成一个输出。

而对于开始和停止录制，我们可以尝试使用Starting and stopping audio graph nodes 来实现。你也可以像“MeeDJ”一样尝试Adding audio effects。

更多功能和示例代码请参考official sample。