Microsoft Silverlight 4 - Tutoriel 20 : Enregistreur audio

Imports System.IO

Inherits AudioSink
Private _stream As MemoryStream ' Memory Sink
Private _format As AudioFormat ' Recording Format

Protected Overloads Overrides Sub OnCaptureStarted()
  _stream = New MemoryStream(1024)
End Sub

Protected Overloads Overrides Sub OnCaptureStopped()
End Sub

Protected Overloads Overrides Sub OnFormatChange(ByVal Format As AudioFormat)
  If Format.WaveFormat <> WaveFormatType.PCM Then
    Throw New InvalidOperationException("MemoryAudioSink only supports PCM Audio")
  End If
  _format = Format
End Sub

Protected Overloads Overrides Sub OnSamples(ByVal sampleTime As Long, _
    ByVal sampleDuration As Long, _
    ByVal sampleData As Byte())
  _stream.Write(sampleData, 0, sampleData.Length) ' Write Audio to Stream
End Sub

Public ReadOnly Property BackingStream() As Stream
  Get
    Return _stream
  End Get
End Property

Public ReadOnly Property CurrentFormat() As AudioFormat
  Get
    Return _format
  End Get
End Property

<Canvas Height="35" Width="400" VerticalAlignment="Top" HorizontalAlignment="Left" Name="Toolbar"></Canvas>
<Canvas Height="35" Width="400" Margin="0,265,0,0" VerticalAlignment="Top" HorizontalAlignment="Left" Name="StatusBar"></Canvas>

<Button Canvas.Left="6" Canvas.Top="6" Height="23" Width="75" Name="Record" Content="Record"/>
<Button Canvas.Left="87" Canvas.Top="6" Height="23" Width="75" Name="Stop" Content="Stop"/>
<Button Canvas.Left="168" Canvas.Top="6" Height="23" Width="75" Name="Save" Content="Save..."/>

<TextBlock Canvas.Left="6" Canvas.Top="6" Height="23" Width="318" FontSize="16" Name="Status"/>

Imports System.IO

Private _source As New CaptureSource
Private _sink As MemoryAudioSink
Private _isRecording As Boolean
Private _hasRecorded As Boolean

_source.AudioCaptureDevice = CaptureDeviceConfiguration.GetDefaultAudioCaptureDevice

Private Function InlineAssignHelper(Of T)(ByRef target As T, ByVal value As T) As T
  target = value
  Return value
End Function

Public Sub SavePcmToWav(ByRef Data As Stream, ByRef Output As Stream, _
    ByRef Format As AudioFormat)
  If Format.WaveFormat <> WaveFormatType.PCM Then
    Throw New ArgumentException("Only PCM coding is supported.")
  End If
  Dim _output As New BinaryWriter(Output)
  ' WAV header
  _output.Write("RIFF".ToCharArray()) ' RIFF chunk
  _output.Write(CUInt((Data.Length + 36))) ' Total Length Of Package To Follow
  _output.Write("WAVE".ToCharArray()) ' WAV chunk
  _output.Write("fmt ".ToCharArray()) ' FORMAT chunk
  _output.Write(CUInt(&H10)) ' Length Of FORMAT Chunk (Binary, always 0x10)
  _output.Write(CUShort(&H1)) ' Always 0x01
  ' Channel Numbers (Always 0x01=Mono, 0x02=Stereo)
  _output.Write(CUShort(Format.Channels))
  _output.Write(CUInt(Format.SamplesPerSecond)) ' Sample Rate (Binary, in Hz)
  _output.Write(CUInt((Format.BitsPerSample * _
  Format.SamplesPerSecond * _
    Format.Channels / 8))) ' Bytes Per Second
  ' Bytes Per Sample: 1=8 bit Mono, 2=8 bit Stereo or 16 bit Mono, 4=16 bit Stereo
  _output.Write(CUShort((Format.BitsPerSample * _
    Format.Channels / 8)))
  _output.Write(CUShort(Format.BitsPerSample)) ' Bits Per Sample
  _output.Write("data".ToCharArray()) ' DATA chunk
  _output.Write(CUInt(Data.Length)) ' Length Of Data To Follow
  ' Raw PCM data
  Dim originalPosition As Long = Data.Position ' Remember Original Position
  Data.Seek(0, SeekOrigin.Begin) ' Reset position in Data
  ' Append all data from Data stream into output stream.
  Dim buffer As Byte() = New Byte(4095) {}
  Dim read As Integer ' number of bytes read in one iteration
  While (InlineAssignHelper(read, Data.Read(buffer, 0, 4096))) > 0
    _output.Write(buffer, 0, read)
  End While
  Data.Seek(originalPosition, SeekOrigin.Begin) ' Restore Original Position
End Sub

If Not _isRecording Then
  If (CaptureDeviceConfiguration.AllowedDeviceAccess _
      Or CaptureDeviceConfiguration.RequestDeviceAccess) _
      And _source.State = CaptureState.Stopped Then
    _sink = New MemoryAudioSink
    _sink.CaptureSource = _source
    _source.Start()
    _isRecording = True
    _hasRecorded = False
    Status.Text = "Recording..."
  End If
End If

If _source.State = CaptureState.Started Then
  _source.Stop()
  _isRecording = False
  _hasRecorded = True
  Status.Text = "Recording Complete"
End If

If _hasRecorded Then
  Dim SaveDialog As New SaveFileDialog
  SaveDialog.Filter = "Audio Files (*.wav)|*.wav"
  If SaveDialog.ShowDialog Then
    Try
      Status.Text = "Saving..."
      Using FileStream As Stream = SaveDialog.OpenFile
        SavePcmToWav(_sink.BackingStream, FileStream, _sink.CurrentFormat)
      End Using
      Status.Text = "Recording Saved"
    Catch ex As Exception
      ' Ignore Errors
    End Try
  End If
Else
  MessageBox.Show("Complete a Recording before Saving", _
    "Audio Recorder", MessageBoxButton.OK)
End If