Recording/Capture Currently Playing Audio

Question

i want to capture/record currently playback audio in UWP or Windows Phone 8.1 any, same thing is done by \"MEE dj\" UWP app in its app, that app is ability to capture currently

Answer 1

You can use the APIs in the Windows.Media.Audio namespace to create audio graphs for audio routing, mixing, and processing scenarios. For how to create audio graphs please reference this article.

An audio graph is a set of interconnected audio nodes. The audio file you want to record supply the "audio input nodes", and "audio output nodes" are the destination for audio processed by the graph, audio can be routed out of the graph to the target audio files. In the "MeeDJ" windows store app, it can mix two audio and record it into one. In this situation we can use "submix nodes" which take audio from one or more nodes and combine them into a single output .

And for starting and stopping recording we can try to use Starting and stopping audio graph nodes to implement. You can also try to Adding audio effects as the "MeeDJ" did.

More features and sample code please reference the official sample.

Answer 2

how to set input nodes playback music instead of mic

Windows.Media.Audio namespace contains AudioDeviceInputNode,AudioDeviceOutputNode,AudioFileInputNode,AudioFileOutputNode and so on. Mic for input is AudioDeviceInputNode, but for play back music file you need to use AudioFileInputNode.

OKay but how can i capture that audio and save it to storage

For saving to storage as I said above, we need to use AudioFileOutputNode. Here is a simple demo, you can load a file for recording, and choose a file from storage for saving the recording result. Code as follows:

XAML Code

<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>

Code behind

  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;
      }
  }

For other complex features, please still reference the official sample.