Windows Phone中的麦克风和播放录音

Question

我开发的应用程序的一部分允许用户使用麦克风录制任何内容。要从麦克风录音，我使用Microphone Code sample by Microsoft中给出的代码。我只是对代码进行了一些更改，以便将wav标头写入流，以便将记录作为波形文件存储在独立存储中。

private void recordButton_Click(object sender, EventArgs e) 
     { 
      // Get audio data in 1/2 second chunks 
      microphone.BufferDuration = TimeSpan.FromMilliseconds(500); 

      // Allocate memory to hold the audio data 
      buffer = new byte[microphone.GetSampleSizeInBytes(microphone.BufferDuration)]; 

      // Set the stream back to zero in case there is already something in it 
      stream.SetLength(0); 

      //Write wav header 
      WriteWavHeader(microphone.SampleRate); 

      // Start recording 
      microphone.Start(); 

      SetButtonStates(false, false, true,false); 
      UserHelp.Text = "record"; 
      StatusImage.Source = microphoneImage; 
      StatusImage.Visibility = System.Windows.Visibility.Visible; 
     } 

     public void WriteWavHeader(int sampleRate) 
     { 
      const int bitsPerSample = 16; 
      const int bytesPerSample = bitsPerSample/8; 
      var encoding = System.Text.Encoding.UTF8; 
      // ChunkID Contains the letters "RIFF" in ASCII form (0x52494646 big-endian form). 
      stream.Write(encoding.GetBytes("RIFF"), 0, 4); 

      // NOTE this will be filled in later 
      stream.Write(BitConverter.GetBytes(0), 0, 4); 

      // Format Contains the letters "WAVE"(0x57415645 big-endian form). 
      stream.Write(encoding.GetBytes("WAVE"), 0, 4); 

      // Subchunk1ID Contains the letters "fmt " (0x666d7420 big-endian form). 
      stream.Write(encoding.GetBytes("fmt "), 0, 4); 

      // Subchunk1Size 16 for PCM. This is the size of therest of the Subchunk which follows this number. 
      stream.Write(BitConverter.GetBytes(16), 0, 4); 

      // AudioFormat PCM = 1 (i.e. Linear quantization) Values other than 1 indicate some form of compression. 
      stream.Write(BitConverter.GetBytes((short)1), 0, 2); 

      // NumChannels Mono = 1, Stereo = 2, etc. 
      stream.Write(BitConverter.GetBytes((short)1), 0, 2); 

      // SampleRate 8000, 44100, etc. 
      stream.Write(BitConverter.GetBytes(sampleRate), 0, 4); 

      // ByteRate = SampleRate * NumChannels * BitsPerSample/8 
      stream.Write(BitConverter.GetBytes(sampleRate * bytesPerSample), 0, 4); 

      // BlockAlign NumChannels * BitsPerSample/8 The number of bytes for one sample including all channels. 
      stream.Write(BitConverter.GetBytes((short)(bytesPerSample)), 0, 2); 

      // BitsPerSample 8 bits = 8, 16 bits = 16, etc. 
      stream.Write(BitConverter.GetBytes((short)(bitsPerSample)), 0, 2); 

      // Subchunk2ID Contains the letters "data" (0x64617461 big-endian form). 
      stream.Write(encoding.GetBytes("data"), 0, 4); 

      // NOTE to be filled in later 
      stream.Write(BitConverter.GetBytes(0), 0, 4); 
     } 

     public void UpdateWavHeader() 
     { 
      //if (!stream.CanSeek) throw new Exception("Can't seek stream to update wav header"); 

      var oldPos = stream.Position; 

      // ChunkSize 36 + SubChunk2Size 
      stream.Seek(4, SeekOrigin.Begin); 
      stream.Write(BitConverter.GetBytes((int)stream.Length - 8), 0, 4); 

      // Subchunk2Size == NumSamples * NumChannels * BitsPerSample/8 This is the number of bytes in the data. 
      stream.Seek(40, SeekOrigin.Begin); 
      stream.Write(BitConverter.GetBytes((int)stream.Length - 44), 0, 4); 

      stream.Seek(oldPos, SeekOrigin.Begin); 
     } 

     private void stopButton_Click(object sender, EventArgs e) 
     { 
      if (microphone.State == MicrophoneState.Started) 
      { 
       // In RECORD mode, user clicked the 
       // stop button to end recording 
       microphone.Stop(); 
       UpdateWavHeader(); 
      } 
      else if (soundInstance.State == SoundState.Playing) 
      { 
       // In PLAY mode, user clicked the 
       // stop button to end playing back 
       soundInstance.Stop(); 
      } 

      SetButtonStates(true, true, false,true); 
      UserHelp.Text = "ready"; 
      StatusImage.Source = blankImage; 
     } 

之后，如果用户选择保存录制内容，我将它保存在独立存储器中。

应用程序中有各种页面，使用麦克风的页面就是其中之一。这个页面做导航是从另一个页面完成：

NavigationService.Navigate(new Uri("/Mic.xaml", UriKind.Relative)); 

现在，当Mic.xaml页面上，有或没有，如果用户点击硬件后退按钮他回到旧的一页记录任何东西。在此页面中，如果他再次导航到Mic.xaml页面，然后尝试录制内容，则录制的文件似乎无法正确录制。录音似乎有问题。

因此，当我们第一次导航到页面时，录制成功，但是当我们第二次或第四次导航时，它不会。

我在模拟器上

Answer 1

微软的样品不适合多页的场景进行测试，离开页面时，他们不清理资源。

首先，把DispatcherTimer在一个领域：

private DispatcherTimer dt; 

然后，更改构造函数，而不是使用初始化一个新的DT这一领域：

this.dt = new DispatcherTimer(); 

最后，覆盖OnNavigateFrom方法检测用户何时离开页面，并清理资源：

protected override void OnNavigatedFrom(System.Windows.Navigation.NavigationEventArgs e) 
    { 
     base.OnNavigatedFrom(e); 

     dt.Stop(); 

     microphone.BufferReady -= this.microphone_BufferReady; 
    }