WaveOutWrite
Aus API-Wiki
Version vom 5. November 2016, 22:11 Uhr von Jochen Wierum (Diskussion | Beiträge)
Die druckbare Version wird nicht mehr unterstützt und kann Darstellungsfehler aufweisen. Bitte aktualisiere deine Browser-Lesezeichen und verwende stattdessen die Standard-Druckfunktion des Browsers.
Die API-Funktion waveOutWrite weißt das Ausgabegerät an, den übergebenen Audiobuffer abzuspielen.
">
Declare Function waveOutWrite lib "winmm.dll" _
Alias "waveOutWrite" ( _
ByVal hWaveOut As Long, _
ByRef lpWaveOutHdr As WAVEHDR, _
ByVal uSize As Long) As Long
Parameter
hWaveOut
- Handle des Devices zu dem der Buffer hinzugefügt werden soll. Siehe waveOutOpen.
lpWaveOutHdr
- Zeiger auf die WAVEHDR Struktur des Buffers. Die Struktur muss mittels waveOutPrepareHeader vorbereitet worden sein.
uSize
- Grösse der übergebenen WAVEHDR Struktur.
Rückgabe(n)
0 bei Erfolg, ansonsten Fehlercode.
Beispiel
In diesem Beispiel wird ein Gerät zur Ausgabe von 16 Bit 44.1kHz Mono Audiodaten geöffnet, zwei Buffer werden reserviert und in diesen werden Testdaten generiert. Schlussendlich werden die beiden Buffer ausgegeben und das Device wieder geschlossen.
">
'Module1
Option Explicit
Private Declare Function waveOutOpen Lib "winmm.dll" (hWaveOut As Long, _
ByVal uDeviceID As Long, Format As Any, ByVal dwCallback As Long, _
ByVal dwInstance As Long, ByVal dwFlags As Long) As Long
Private Declare Function waveOutPrepareHeader Lib "winmm.dll" ( _
ByVal hWaveOut As Long, lpWaveInHdr As Any, ByVal uSize As Long) As Long
Private Declare Function waveOutUnprepareHeader Lib "winmm.dll" ( _
ByVal hWaveOut As Long, lpWaveInHdr As Any, ByVal uSize As Long) As Long
Private Declare Function waveOutClose Lib "winmm.dll" (ByVal hWaveOut As Long) As Long
Private Declare Function waveOutWrite Lib "winmm.dll" (ByVal hWaveOut As Long, _
ByRef lpWaveOutHdr As WAVEHDR, ByVal uSize As Long) As Long
Private Type WAVEFORMATEX
wFormatTag As Integer
nChannels As Integer
nSamplesPerSec As Long
nAvgBytesPerSec As Long
nBlockAlign As Integer
wBitsPerSample As Integer
cbSize As Integer
End Type
Private Type WAVEHDR
lpData As Long
dwBufferLength As Long
dwBytesRecorded As Long
dwUser As Long
dwFlags As Long
dwLoops As Long
lpNext As Long
Reserved As Long
End Type
Private Const WAVE_FORMAT_PCM As Long = 1
Private Const CALLBACK_FUNCTION As Long = &H30000
Private Const INVALID_HANDLE_VALUE As Long = -1
Private Const WOM_DONE As Long = &H3BD
Private hDevice As Long
Private udtBuffer1Hdr As WAVEHDR
Private btWaveOutBuffer1() As Byte
Private udtBuffer2Hdr As WAVEHDR
Private btWaveOutBuffer2() As Byte
Private lBufferFinished As Long
Public Sub TestAudioOutput()
If OpenOutputDevice(0) Then
CreateTestData
If Not waveOutWrite(hDevice, udtBuffer1Hdr, LenB(udtBuffer1Hdr)) = 0 Then
'error
ElseIf Not waveOutWrite(hDevice, udtBuffer2Hdr, LenB(udtBuffer2Hdr)) = 0 Then
'error
End If
Do While lBufferFinished <> 0
'warten bis beide Buffer abgespielt wurden
Loop
CloseOutputDevice
Else
Debug.Print "Kann Gerät 0 nicht öffnen!"
End If
End Sub
Private Sub CreateTestData()
'Diese Funktion erstellt zwei verschiedene Wellenformen in den beiden Buffern
'damit ein Unterschied hörbar ist.
Dim x As Long
Dim lSample As Long
'Sägezahn Schwingung in Buffer 1:
lSample = 0
For x = 0 To UBound(btWaveOutBuffer1) Step 2
lSample = lSample + 5
If lSample > 32767 Then
lSample = 0
End If
btWaveOutBuffer1(x) = (lSample And &HFF00&) \ &H100
btWaveOutBuffer1(x + 1) = lSample And &HFF&
Next
'Sägezahn Schwingung in Buffer 2:
lSample = 0
For x = 0 To UBound(btWaveOutBuffer2) Step 2
lSample = lSample + 8
If lSample > 32767 Then
lSample = 0
End If
btWaveOutBuffer2(x) = (lSample And &HFF00&) \ &H100
btWaveOutBuffer2(x + 1) = lSample And &HFF&
Next
End Sub
Public Function OpenOutputDevice(DevID As Long) As Boolean
Dim udtWaveFormat As WAVEFORMATEX
'Definition des abzuspielenden Formats:
With udtWaveFormat
.cbSize = 0
.wFormatTag = WAVE_FORMAT_PCM 'wave format
.nChannels = 1 'mono
.nSamplesPerSec = 44100 '44.1 kHz
.wBitsPerSample = 16 '16 Bits pro Sample
.nBlockAlign = .nChannels * .wBitsPerSample / 8
.nAvgBytesPerSec = .nSamplesPerSec * .nBlockAlign
End With
If waveOutOpen(hDevice, DevID, udtWaveFormat, AddressOf CallBack, 0, CALLBACK_FUNCTION) <> 0 Then
'Failed
hDevice = INVALID_HANDLE_VALUE
Else
'Device erfolgreich geöffnet, jetzt zwei buffer, jeweils 1/4 sekunde
'16 bit audio reservieren:
ReDim btWaveOutBuffer1(udtWaveFormat.nSamplesPerSec * udtWaveFormat.nBlockAlign * 0.25 - 1)
ReDim btWaveOutBuffer2(udtWaveFormat.nSamplesPerSec * udtWaveFormat.nBlockAlign * 0.25 - 1)
With udtBuffer1Hdr
.lpData = VarPtr(btWaveOutBuffer1(0))
.dwBufferLength = UBound(btWaveOutBuffer1) + 1
.dwUser = 1
End With
With udtBuffer2Hdr
.lpData = VarPtr(btWaveOutBuffer2(0))
.dwBufferLength = UBound(btWaveOutBuffer2) + 1
.dwUser = 2
End With
If waveOutPrepareHeader(hDevice, udtBuffer1Hdr, LenB(udtBuffer1Hdr)) Or _
waveOutPrepareHeader(hDevice, udtBuffer2Hdr, LenB(udtBuffer2Hdr)) <> 0 Then
CloseOutputDevice
Else
lBufferFinished = 3
OpenOutputDevice = True
End If
End If
End Function
Public Function CloseOutputDevice()
If hDevice <> INVALID_HANDLE_VALUE Then
waveOutUnprepareHeader hDevice, udtBuffer1Hdr, LenB(udtBuffer1Hdr)
waveOutUnprepareHeader hDevice, udtBuffer2Hdr, LenB(udtBuffer2Hdr)
waveOutClose hDevice
hDevice = INVALID_HANDLE_VALUE
End If
End Function
Private Sub CallBack(ByVal hDev As Long, ByVal uMsg As Long, dwInstance As Long, _
dwParam1 As WAVEHDR, dwParam2 As Long)
'Achtung: innerhalb der Callback Funktion dürfen nur wenige Funktionen und API Calls erfolgen!
'MSDN:
'Applications should not call any system-defined functions from inside a callback function,
'except for EnterCriticalSection, LeaveCriticalSection, midiOutLongMsg, midiOutShortMsg,
'OutputDebugString, PostMessage, PostThreadMessage, SetEvent, timeGetSystemTime, timeGetTime,
'timeKillEvent, and timeSetEvent. Calling other wave functions will cause deadlock.
'
'Zu bedenken ist auch, dass viele VB Funktionen ihrerseits im Hintergrund APIs aufrufen und dies
'die Limitierungen verletzen könnte. Ein Zuwiederhandeln zeigt sich meist erst in der kompilierten
'EXE (Absturz) wohingegen der Code in der IDE fehlerfrei läuft!
If uMsg = WOM_DONE Then
lBufferFinished = lBufferFinished And (Not dwParam1.dwUser)
End If
End Sub
Quelle(n)
- MSDN US-Libary