'***************************************************************************
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'* Class frmAudio *
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'* *
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'* This form manages the audio transmission to and from the E301 modules. *
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'* The audio format choosen is the ITU G.711-A law (8 bits/sample, 8Ks/s, *
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'* non-linearized to reduce noise). *
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'* *
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'* The transport protocol is RTP over UDP, according to RFC's 3550 and *
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'* 3551 *
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'* *
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'* For the computer audio management, Managed DirectX SDK is used. *
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'* *
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'* See more info in ClassRTPAgent.Vb, the Microsoft DirectX documentation *
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'* and the correspondant RFC's and standards. *
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'* *
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'* This form includes two graphical signal analyzers (one for audio sent *
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'* and one for the audio received) for debug and demonstration purposes *
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'* only. *
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'* *
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'* Also provides a tone and a chirp generator very usefull in testing the *
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'* audio quality of the phones. * *
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'* *
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'* IMPORTANT NOTE: The DirectX audio part of the application is not fully *
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'* debugged. Is an adaptation of the microsoft examples provided with the *
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'* DirectX SDK. It is given as a starting point and mainly to demonstrate *
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'* the audio RTP encapsulation. *
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'* *
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'* EQUITEL C.V. February 2007 ALMDI*
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'***************************************************************************
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Imports System
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Imports System.Math
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Imports System.Threading
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Imports Microsoft.DirectX
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Imports Microsoft.DirectX.DirectSound
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Public Class frmAudio
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#Region "Definitions"
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#Region "General definitions"
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'When sending audio via RTP according to the G.711(A-law) standard,
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'each packet has to be 20 miliseconds: 20 ms * 80 samples/ms = 160 samples
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Private Const AudioSamplesPerPacket As Integer = 160
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'Size in bytes of the audio packet from/to the computer audio system
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'(160 Samples/packet * 2 Bytes/sample = 320 bytes/packet)
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Private Const PCMAudioPacketLength As Integer = 320
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'Object to send and receive audio packets with RTP/UDP protocol
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Private RTPAgent As ClassRTPAgent
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'Object to hold the format of the audio (see directX documentation)
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Private AudioFormat As WaveFormat
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'Indicates if the audio engine to read and send audio to the PC is created
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Private AudioDevicesSelected As Boolean = False
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'Indicates if the audio is active
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Private AudioON As Boolean = False
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'Indicates if we are sending a sinusoidal tone to the E301 instead the actual audio
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Private ToneON As Boolean = False
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'Indicates if we are sending a chirp tone to the E301...
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Private ChirpON As Boolean = False
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'Holds which phone attached to the E301 is active
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Public MasterOrSlave As Byte
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'Form of the tone generator
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Private WithEvents ToneWindow As frmTone
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'Form of the Chirp generator
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Private WithEvents ChirpWindow As frmChirp
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#End Region
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#Region "DirectX Audio input definitions"
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Private RecordDevice As Capture = Nothing
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Private RecordBuffer As CaptureBuffer = Nothing
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Private Const NumberRecordNotifications As Integer = 16
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Private RecordPositionNotify(NumberRecordNotifications) As BufferPositionNotify
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Private RecordNotificationEvent As AutoResetEvent = Nothing
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Private RecordNotify As Notify = Nothing
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Private RecordThread As Thread = Nothing
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Private RecordBufferSize As Integer = 0
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Private RecordNextOffset As Integer = 0
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Private RecordNotifySize As Integer = 0
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#End Region
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#Region "DirectX Audio output definitions"
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Private PlayDevice As Microsoft.DirectX.DirectSound.Device
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Private PlayBuffer As Microsoft.DirectX.DirectSound.SecondaryBuffer
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Private Const NumberPlayNotifications As Integer = 16
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Private PlayPositionNotify(NumberRecordNotifications) As BufferPositionNotify
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Private PlayBufferSize As Integer = 0
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Private PlayNotifySize As Integer = 0
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Private PlayNextOffset As Integer = 0
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Private PlayThread As Thread = Nothing
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Private PlayNotificationEvent As AutoResetEvent = Nothing
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Private PlayNotify As Notify = Nothing
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#End Region
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#Region "Events"
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Public Event Log(ByVal Texto As String)
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#End Region
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#End Region
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#Region "Methods"
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#Region "Audio management"
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Private Sub SelectAudioDevices()
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'Audio format: 16 bit/sample, 8000 samples/second, 1 channel, PCM
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AudioFormat.BitsPerSample = 16
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AudioFormat.Channels = 1
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AudioFormat.SamplesPerSecond = 8000
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AudioFormat.FormatTag = WaveFormatTag.Pcm
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AudioFormat.BlockAlign = CShort(AudioFormat.Channels * (AudioFormat.BitsPerSample / 8))
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AudioFormat.AverageBytesPerSecond = AudioFormat.BlockAlign * AudioFormat.SamplesPerSecond
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'Select the audio input and ouput devices
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If SelectInputDevice() Then
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If Not SelectOutputDevice() Then
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MsgBox("ERROR: unable to create the audio output device")
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Close()
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Else
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AudioDevicesSelected = True
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End If
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Else
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MsgBox("Error: unable to create the audio input device")
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Close()
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End If
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End Sub
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Public Sub AudioStart(ByVal DestinationIP As String, ByVal DestinationPort As Integer, ByVal LocalPort As Integer, ByVal mMasterOrSlave As Byte)
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'Select the audio devices if not selcted yet
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If Not AudioDevicesSelected Then SelectAudioDevices()
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If Not AudioON Then
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'Initialize analyzers
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ToIPAnalyzer.Initialize()
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FromIPAnalyzer.Initialize()
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'Create the RTP Agent
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RTPAgent = New ClassRTPAgent(DestinationIP, DestinationPort, LocalPort)
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'Create the input notify engine and begin audio capture
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CreateInputNotify()
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RecordBuffer.Start(True)
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'Create the output notify engine and begin audio output
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CreateOutputNotify()
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PlayBuffer.Play(0, BufferPlayFlags.Looping)
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'Store the state
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MasterOrSlave = mMasterOrSlave
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AudioON = True
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End If
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End Sub
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Public Sub AudioStop()
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If AudioON Then
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'Dispose the event monitoring threads
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PlayThread.Abort()
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RecordThread.Abort()
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'Stop the audio capture and output
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If Not RecordBuffer Is Nothing Then
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RecordBuffer.Stop()
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End If
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If Not PlayBuffer Is Nothing Then
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PlayBuffer.Stop()
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End If
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'Dispose the RTP agent
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RTPAgent.Dispose()
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RTPAgent = Nothing
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AudioON = False
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End If
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End Sub
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#End Region
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#Region "Audio input from soundcard"
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Private Function SelectInputDevice() As Boolean
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Dim DevCol As New CaptureDevicesCollection
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Dim CaptureDeviceGuid As Guid = Guid.Empty
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'We select the first audio interface avalaible in the computer
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'In computer with more than one audio interfaces, this code may
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'be changed to select wich one to use.
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'The sound source is the choosen one by the user in the operative system.
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Try
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CaptureDeviceGuid = DevCol(0).DriverGuid
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RecordDevice = New Capture(CaptureDeviceGuid)
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Catch
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End Try
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Return Not (RecordDevice Is Nothing)
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End Function
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Private Sub CreateInputNotify()
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'Creates the input object to read data from the PC audio card.
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Dim Desc As New CaptureBufferDescription()
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Dim i As Integer
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'If it is already created, dispose it and create again
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If Not RecordNotify Is Nothing Then
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RecordNotify.Dispose()
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RecordNotify = Nothing
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End If
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If Not RecordBuffer Is Nothing Then
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RecordBuffer.Dispose()
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RecordBuffer = Nothing
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End If
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'We want to be advised each time a audio packet of PCMAudioPacket
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'bytes is ready to be read. Tis size must be multiple of AudioFormat.BlockAlign
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RecordNotifySize = PCMAudioPacketLength
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RecordNotifySize -= RecordNotifySize Mod AudioFormat.BlockAlign
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'The total buffer size must be the product of the RecordNotifySize by the
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'number of notifications we want
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RecordBufferSize = RecordNotifySize * NumberRecordNotifications
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'Buffer creation
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Desc.BufferBytes = RecordBufferSize
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Desc.Format = AudioFormat
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Desc.WaveMapped = True
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Try
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RecordBuffer = New CaptureBuffer(Desc, RecordDevice)
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Catch e As Exception
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MsgBox("ERROR opening audio device.", MsgBoxStyle.Critical)
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Close()
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End Try
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RecordNextOffset = 0
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If Nothing Is RecordBuffer Then
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MsgBox("ERROR opening audio device.", MsgBoxStyle.Critical)
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Close()
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End If
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'This object will indicate when an audio packet is ready to be read from
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'the audio card
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RecordNotificationEvent = New AutoResetEvent(False)
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'We configure the object RecordPositionNotify to indicate the postitions of the buffer
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'that must signal an event when reached
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For i = 0 To NumberRecordNotifications - 1
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'Position of the buffer
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RecordPositionNotify(i).Offset = RecordNotifySize * (i + 1) - 1
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'Handler to the event generator object
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RecordPositionNotify(i).EventNotifyHandle = RecordNotificationEvent.SafeWaitHandle.DangerousGetHandle
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Next i
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'Tell DirectSound when to notify the app. The notification will come in the from
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'of signaled events that are handled in the notify thread.
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RecordNotify = New Notify(RecordBuffer)
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RecordNotify.SetNotificationPositions(RecordPositionNotify, NumberRecordNotifications)
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'Create a thread to monitor the notify events
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RecordThread = New Thread(New ThreadStart(AddressOf InputProcess))
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RecordThread.Start()
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End Sub
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Private Sub InputProcess()
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'Monitoring thread for the audio input events
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While True
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'Wait until a new audio packet is ready
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If RecordNotificationEvent.WaitOne(1000, True) Then
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ReadAudio()
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Else
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RaiseEvent Log("Timeout waiting for audio input from PC")
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End If
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End While
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End Sub
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Private Sub ReadAudio()
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'We enter here each 20 miliseconds to read a new audio packet
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'from the PC audio card
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'Packet to be read
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Dim ReadPacket(AudioSamplesPerPacket) As Short
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'Pointers to read the DirectSound buffer
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Dim ReadPos As Integer
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Dim CapturePos As Integer
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Dim LockSize As Integer
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'If recordBuffer is not created then do nothing
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If RecordBuffer Is Nothing Then
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Return
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End If
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RecordBuffer.GetCurrentPosition(CapturePos, ReadPos)
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LockSize = ReadPos - RecordNextOffset
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If LockSize < 0 Then
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LockSize += RecordBufferSize
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End If
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'Block align lock size so that we are always write on a boundary
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LockSize -= LockSize Mod RecordNotifySize
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If 0 = LockSize Then
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Return
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End If
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'Read the capture buffer.
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Try
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'If we must send tone instead real audio, get the packet from the tone generation window
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'If ToneON Then
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'ToneWindow.ToneGenerator.OutputPacket(ReadPacket, AudioSamplesPerPacket)
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'Else
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'The same with the Chirp tone
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'If ChirpON Then
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'ChirpWindow.ChirpGenerator.OutputPacket(ReadPacket, AudioSamplesPerPacket)
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'Else
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'Actual read from the PC audio card
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ReadPacket = RecordBuffer.Read(RecordNextOffset, GetType(Short), LockFlag.None, LockSize)
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'End If
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'End If
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'RTP packet send
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RTPAgent.SendAudioPacket(ReadPacket)
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Catch e As Exception
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RaiseEvent Log("Error in audio input" + e.ToString)
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End Try
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'Signal analyzer update
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''''''' ToIPAnalyzer.NewAudioPacket(ReadPacket, AudioSamplesPerPacket)
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' Move the capture offset along
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RecordNextOffset += ReadPacket.Length
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RecordNextOffset = RecordNextOffset Mod RecordBufferSize ' Circular buffer
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End Sub
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#End Region
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#Region "Audio output to soundcard"
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Private Function SelectOutputDevice() As Boolean
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Dim DevCol As New Microsoft.DirectX.DirectSound.DevicesCollection()
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Dim DeviceGuid As Guid
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'We select the first audio interface avalaible in the computer
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'In computer with more than one audio interfaces, this code may
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'be changed to select wich one to use.
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Try
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DeviceGuid = DevCol(0).DriverGuid
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PlayDevice = New Microsoft.DirectX.DirectSound.Device(DeviceGuid)
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Catch
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End Try
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If Not PlayDevice Is Nothing Then
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PlayDevice.SetCooperativeLevel(Me, CooperativeLevel.Priority)
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End If
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Return Not (PlayDevice Is Nothing)
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End Function
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Private Sub CreateOutputNotify()
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'Creates the output system to send data to the PC audio card
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Dim Desc As New Microsoft.DirectX.DirectSound.BufferDescription()
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Dim Silencio As Byte()
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Dim i As Integer
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'If it is already created, dispose it and create again
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If Not PlayNotify Is Nothing Then
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PlayNotify.Dispose()
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PlayNotify = Nothing
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End If
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If Not PlayBuffer Is Nothing Then
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PlayBuffer.Dispose()
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PlayBuffer = Nothing
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End If
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'We want to be advised each time buffer of PCMAudioPacket
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'bytes is ready to be written. Tis size must be multiple of AudioFormat.BlockAlign
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PlayNotifySize = PCMAudioPacketLength
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PlayNotifySize -= PlayNotifySize Mod AudioFormat.BlockAlign
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'The total buffer size must be the product of the RecordNotifySize by the
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'number of notifications we want
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PlayBufferSize = RecordNotifySize * NumberPlayNotifications
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'Create the output buffer with the same format than the input one
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Desc.Format = RecordBuffer.Format
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Desc.BufferBytes = PlayBufferSize
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Desc.ControlPositionNotify = True
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Desc.CanGetCurrentPosition = True
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If PlayBuffer Is Nothing Then
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PlayBuffer = New Microsoft.DirectX.DirectSound.SecondaryBuffer(Desc, PlayDevice)
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End If
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'Fill the buffer with silience
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ReDim Silencio(PlayBufferSize - 1)
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For i = 0 To PlayBufferSize - 1
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Silencio(i) = 0
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Next
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PlayBuffer.Write(0, Silencio, LockFlag.None)
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'This object will indicate when an audio packet is needed to be written to
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'the audio card
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PlayNotificationEvent = New AutoResetEvent(False)
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'We configure the object RecordPositionNotify to indicate the postitions of the buffer
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'that must signal an event when reached
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For i = 0 To NumberPlayNotifications - 1
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PlayPositionNotify(i).Offset = PlayNotifySize * i + PlayNotifySize - 1
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PlayPositionNotify(i).EventNotifyHandle = PlayNotificationEvent.SafeWaitHandle.DangerousGetHandle
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Next i
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PlayNotify = New Notify(PlayBuffer)
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'Tell DirectSound when to notify the app. The notification will come in the from
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'of signaled events that are handled in the notify thread.
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PlayNotify.SetNotificationPositions(PlayPositionNotify, NumberPlayNotifications)
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'Create a thread to monitor the notify events
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PlayThread = New Thread(New ThreadStart(AddressOf OutputProcess))
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PlayThread.Start()
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End Sub
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Private Sub OutputProcess()
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'Monitoring thread for the audio output events
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While True
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'Wait until a new audio packet is needed
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If PlayNotificationEvent.WaitOne(1000, True) Then
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OutputAudio()
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Else
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RaiseEvent Log("Timeout waiting for audio output to PC")
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End If
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End While
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End Sub
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Private Sub OutputAudio()
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'Each 20 miliseconsd we must send a new audio packet to the
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'PC audio card
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Dim ReceivedPacket(AudioSamplesPerPacket) As Short
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Dim WritePos As Integer
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Dim PlayPos As Integer
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Dim LockSize As Integer
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'If PlayBuffer is not created yet, do nothing
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If PlayBuffer Is Nothing Then
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Return
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End If
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'Get the writting position in the buffer
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PlayBuffer.GetCurrentPosition(PlayPos, WritePos)
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LockSize = WritePos - PlayNextOffset
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If LockSize < 0 Then
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LockSize += PlayBufferSize
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End If
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' Block align lock size so that we are always write on a boundary
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LockSize -= LockSize Mod PlayNotifySize
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If 0 = LockSize Then
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Return
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End If
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'Get a new audio packet from the RTP agent (i.e. from the E301 module)
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ReceivedPacket = RTPAgent.ReceivedAudioPacket
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'If we have to send the audio to the PC sound card, copy this packet to the
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'play buffer. Else, the silent play buffer continues playing.
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'If Not ChkSilent.Checked Then
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PlayBuffer.Write(PlayNextOffset, ReceivedPacket, LockFlag.None)
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'End If
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'Update the signal analyzer
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FromIPAnalyzer.NewAudioPacket(ReceivedPacket, AudioSamplesPerPacket)
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' Move the capture offset along
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PlayNextOffset += PCMAudioPacketLength
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PlayNextOffset = PlayNextOffset Mod PlayBufferSize ' Circular buffer
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End Sub
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#End Region
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#Region "Form and controls behaviour"
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Private Sub ChkSilent_CheckedChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles ChkSilent.CheckedChanged
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'Sometimes, can be usefull to not send the actual audio to the PC audio system.
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'If you send to the E301 the output of the PC wave mixer, the same output
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'you are hearing, sending the real incoming audio to the PC will make a loop.
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'With this utility you can break the loop and allows you to send easily any audio
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'you can hear in the PC to the sos phone (music etc.)
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Dim i As Integer
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Dim Silence As Byte()
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If ChkSilent.Checked Then
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If Not PlayBuffer Is Nothing Then
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'Clear the play buffer
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ReDim Silence(PlayBufferSize - 1)
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For i = 0 To PlayBufferSize - 1
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Silence(i) = 0
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Next
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PlayBuffer.Write(0, Silence, LockFlag.None)
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End If
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End If
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End Sub
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Private Sub MainForm_Closing(ByVal sender As Object, ByVal e As System.ComponentModel.CancelEventArgs) Handles MyBase.Closing
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If Not RecordNotificationEvent Is Nothing Then
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RecordNotificationEvent.Set()
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End If
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If Not PlayNotificationEvent Is Nothing Then
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PlayNotificationEvent.Set()
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End If
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AudioStop()
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End Sub
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Private Sub ToneWindow_FormClosing(ByVal sender As Object, ByVal e As System.Windows.Forms.FormClosingEventArgs) Handles ToneWindow.FormClosing
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ToneON = False
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BtnTone.Enabled = True
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BtnChirp.Enabled = True
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End Sub
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Private Sub BtnTone_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles BtnTone.Click
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BtnTone.Enabled = False
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BtnChirp.Enabled = False
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ToneWindow = New frmTone
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ToneON = True
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ToneWindow.Show()
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End Sub
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Private Sub BtnChirp_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles BtnChirp.Click
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BtnTone.Enabled = False
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BtnChirp.Enabled = False
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ChirpWindow = New frmChirp
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ChirpON = True
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ChirpWindow.Show()
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End Sub
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Private Sub ChirpWindow_FormClosing(ByVal sender As Object, ByVal e As System.Windows.Forms.FormClosingEventArgs) Handles ChirpWindow.FormClosing
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ChirpON = False
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BtnTone.Enabled = True
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BtnChirp.Enabled = True
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End Sub
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#End Region
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#End Region
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Public Sub New()
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' Llamada necesaria para el Diseñador de Windows Forms.
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InitializeComponent()
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' Agregue cualquier inicialización después de la llamada a InitializeComponent().
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'Hide()
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End Sub
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Private Sub GroupBox1_Enter(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles GroupBox1.Enter
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End Sub
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End Class
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