VB中使用DirectX库的简明教程(4)

 四、 DirectSound

　　DirectSound类对象是DirectX中播放、捕捉数字声音对象并且对声音在虚拟的三维控件内进行定位。

　　它主要包括以下的几个对象：

DirectSound
DirectSoundBuffer
DirectSound3DBuffer
Direct3DsoundListner
DirectSoundCapture
DirectSoundCaptureBuffer

　　DirectSound对象和DirectSoundCapture对象是DirectSound类对象的基本对象，DirectSound对象是音频播放基本对象，而DirectSoundCapture对象是音频捕捉基本对象。利用DirectX7对象的DirectSoundCreate方法和DirectSoundCaptureCreate方法可以分别建立DirectSound对象和DirectSoundCapture对象。

　　DirectSoundBuffer对象和DirectSound3Dbuffer是音频播放缓冲对象，顾名思义，前者是音频播放对象，而后者是三维音频播放对象。Direct3DSoundListner对象用于设置播放三维音频时收听者所处的位置。

　　下面通过一个程序来介绍DirectSound的应用，这个程序可以利用DirectSound3DBuffer播放文件并可以动态的设置声音位置。首先建立一个工程文件，在其中加入DirectX7说明库，然后在Form1中加入一个PictureBox控件和两个CommandButton控件。将Picture1的Width和Height属性都设置为3000。将Picture1的Scale属性设置为3-Pixel。保存工程文件，并在工程所在的目录下放置一个名为 Demo.wav 的声音文件。在Form1的代码窗口加入以下代码：

Dim m_dx As New DirectX7

Dim m_ds As DirectSound
Dim m_dsBuffer As DirectSoundBuffer
Dim m_ds3dBuffer As DirectSound3DBuffer
Dim m_dsPrimaryBuffer As DirectSoundBuffer
Dim m_dsListener As DirectSound3DListener
Dim m_pos As D3DVECTOR

Sub DrawPositions()
Dim X As Integer
Dim z As Integer

Picture1.Cls

'以黑色圈标出收听者所在的位置
Picture1.Circle (Picture1.ScaleWidth / 2, Picture1.ScaleHeight / 2), 4

'以红色圈标出声音所在的位置
X = CInt(m_pos.X) + Picture1.ScaleWidth / 2
z = CInt(m_pos.z) + Picture1.ScaleHeight / 2
Picture1.Circle (X, z), 4, RGB(255, 0, 0)
End Sub

Sub Load(sFile As String)
Dim bufferDesc1 As DSBUFFERDESC
Dim waveFormat1 As WAVEFORMATEX

'设置将建立的DirectSoundBuffer对象的属性
bufferDesc1.lFlags = (DSBCAPS_CTRL3D Or DSBCAPS_CTRLFREQUENCY Or _
DSBCAPS_CTRLPAN Or DSBCAPS_CTRLVOLUME) Or DSBCAPS_STATIC
'建立DirectSoundBuffer对象
Set m_dsBuffer = m_ds.CreateSoundBufferFromFile(sFile, bufferDesc1, _
waveFormat1)
'设置DirectSoundBuffer对象的声音（0为最大）
m_dsBuffer.SetVolume 0
'设置DirectSoundBuffer对象
Set m_ds3dBuffer = m_dsBuffer.GetDirectSound3DBuffer

'设置DirectSoundBuffer对象的播放方向属性
m_ds3dBuffer.SetConeOrientation 1, 1, 1, DS3D_IMMEDIATE
m_ds3dBuffer.SetConeAngles DS3D_MINCONEANGLE, 100, DS3D_IMMEDIATE
m_ds3dBuffer.SetConeOutsideVolume -100, DS3D_IMMEDIATE

'设置DirectSoundBuffer对象的播放位置属性
m_ds3dBuffer.SetPosition m_pos.X / 50, 0, m_pos.z / 50, DS3D_IMMEDIATE
End Sub

Sub UpdatePosition(X As Single, z As Single)
m_pos.X = X - Picture1.ScaleWidth / 2
m_pos.z = z - Picture1.ScaleHeight / 2

DrawPositions

If m_ds3dBuffer Is Nothing Then Exit Sub
'重新设置DirectSoundBuffer对象的播放位置属性
m_ds3dBuffer.SetPosition m_pos.X / 50, 0, m_pos.z / 50, DS3D_IMMEDIATE
End Sub

Private Sub Command1_Click()
If m_dsBuffer Is Nothing Then
Call Load(App.Path + "/demo.wav")
End If
'循环播放声音文件
m_dsBuffer.Play 1
End Sub

Private Sub Command2_Click()
If m_dsBuffer Is Nothing Then Exit Sub
m_dsBuffer.Stop
m_dsBuffer.SetCurrentPosition 0
End Sub

Private Sub Form_Load()
Dim i As Integer

Command1.Caption = "播放"
Command2.Caption = "停止"
Me.Show
DoEvents
On Local Error Resume Next
'建立DirectSound对象
Set m_ds = m_dx.DirectSoundCreate(vbNullString)

If Err.Number <> 0 Then
MsgBox "无法佳丽DirectSound对象，请查看声卡或驱动程序是否安装正确"
End
End If
'设置DirectSound对象的协作模式
m_ds.SetCooperativeLevel Me.hWnd, DSSCL_PRIORITY

Dim primDesc As DSBUFFERDESC, format As WAVEFORMATEX

primDesc.lFlags = DSBCAPS_CTRL3D Or DSBCAPS_PRIMARYBUFFER
'建立主声音缓冲对象
Set m_dsPrimaryBuffer = m_ds.CreateSoundBuffer(primDesc, format)
'建立DirectSound3DListener对象
Set m_dsListener = m_dsPrimaryBuffer.GetDirectSound3DListener()

m_pos.X = 10: m_pos.z = 50
UpdatePosition m_pos.X, m_pos.z
End Sub

Private Sub Picture1_MouseDown(Button As Integer, Shift As Integer, X As Single, Y As Single)
If Button = 1 Then
UpdatePosition X, Y
End If
End Sub

Private Sub Picture1_Paint()
DrawPositions
End Sub
　　运行程序，在PictureBox中回出现一个黑色和一个红色的小圆圈。黑色的代表虚拟的收听者的位置，红色的代表音源的位置。点击"播放"按钮即可以播放Demo.wav文件，你可以点击PictureBox中的不同位置来设置音源的位置，然后再听一下声音发生的改变，在本人的爱机上安装的只是普通双声道声卡，所以效果不是很明显，有高档多声道声卡的朋友可以使用上面的程序感受一下你的声卡的三维效果。

　　五、 DirectMusic

　　同DirectSound类对象不同，DirectMusic类对象负责控制对于音乐数据进行播放（象一个MIDI文件）。

　　DirectMusic对象类主要包括以下对象：

DirectMusicLoader
DirectMusicPerformance
DirectMusicSegment

DirectMusicLoader对象负责装载音乐数据文件，利用DirectX7对象的
DirectMusicLoaderCreate方法可以建立一个DirectMusicLoader对象。
DirectMusicSegment对象描述了一个音乐片断
DirectMusicPerformance对象负责对音乐数据回放进行全面控制。它可以定位音乐数据输出通道、播放音乐片断、发送消息、处理事件、获取音乐数据的相关信息等。利用DirectX7的DirectMusicPerformanceCreate方法可以建立一个DirectMusicPerformance对象。

　　下面是一个具体的利用DirectMusic类对象播放音乐数据文件的范例程序。首先建立一个新的工程文件，加入DirectX7说明库，然后在Form1中加入4个CommandButton控件，3个Label控件，一个CommonDialog控件和一个Timer控件。然后在Form1德代码窗口中加入以下代码：

Option Explicit

Private Declare Sub Sleep Lib "kernel32" (ByVal lMilliseconds As Long)

Dim objDX As New DirectX7
Dim objDMLoader As DirectMusicLoader
Dim objDMPerf As DirectMusicPerformance
Dim objDMSeg As DirectMusicSegment
Dim objDMSegSt As DirectMusicSegmentState
Dim DTimesig As DMUS_TIMESIGNATURE
Dim portcaps As DMUS_PORTCAPS

Dim lTimePassed As Long
Dim lMTime As Long
Dim lTempo, GetStartTime, Offset As Long
Dim ElapsedTime2 As Long
Dim ElapsedTime, sAllTime As String
Dim fIsPaused As Boolean
Sub GetTimePassed()
Dim min As Integer
Dim a As Single

'首先确定objDMSegSt以及objDMPerf是否有效
If objDMSegSt Is Nothing Or objDMPerf Is Nothing Then
Exit Sub
End If


'处于播放状态
If objDMPerf.IsPlaying(Nothing, objDMSegSt) = True Then
'获得以秒计算的播放时间
ElapsedTime2 = ((((objDMPerf.GetMusicTime() - (objDMSegSt.GetStartTime() _
- Offset)) / 768) * 60) / lTempo)

'获得分钟
min = 0
a = ElapsedTime2 - 60
Do While a >= 0
min = min + 1
a = a - 60
Loop
ElapsedTime = Format(min, "00") & ":" & Format(Abs((ElapsedTime2 - (min * 60))), "00.0")
Else
If fIsPaused Then
Else
ElapsedTime = "00:00.0"
End If
End If
End Sub
Private Sub Command1_Click()
Set objDMLoader = Nothing
Set objDMLoader = objDX.DirectMusicLoaderCreate

CommonDialog1.Filter = "MIDI Files (*.mid)|*.mid" ' Set filters
CommonDialog1.InitDir = App.Path
CommonDialog1.ShowOpen

If Dir$(CommonDialog1.FileName) <> "" Then
Me.Caption = CommonDialog1.FileName
'读入MIDI文件
Set objDMSeg = objDMLoader.LoadSegment(CommonDialog1.FileName)

'获得MIDI文件的播放时间
lMTime = objDMPerf.GetMusicTime()
'播放一定程度的MIDI文件以获取文件信息
Call objDMPerf.PlaySegment(objDMSeg, 0, lMTime + 2000)

'获取MIDI播放速度
lTempo = objDMPerf.GetTempo(lMTime + 2000, 0)
Label2.Caption = "MIDI速度" + Format(lTempo, "00.00")

'获得MIDI节拍信息
Call objDMPerf.GetTimeSig(lMTime + 2000, 0, DTimesig)
Label3.Caption = "MIDI节拍" & DTimesig.beatsPerMeasure & "/" & DTimesig.beat

Dim a, Minutes, mtlength As Long
'获得MIDI播放长度
mtlength = (((objDMSeg.GetLength() / 768) * 60) / lTempo)

Minutes = 0
a = mtlength - 60
Do While a > 0
Minutes = Minutes + 1
a = a - 60
Loop
Label1.Caption = "MIDI播放时间" + Format(Minutes, "00") & ":" & _
Format((mtlength - (Minutes * 60)), "00.0")
sAllTime = Format(Minutes, "00") & ":" & Format((mtlength - (Minutes * 60)), "00.0")
'已经获得足够长度的MIDI文件信息，停止播放
Call objDMPerf.Stop(objDMSeg, Nothing, 0, 0)
objDMSeg.SetStandardMidiFile

Command2.Enabled = True
Else
Command2.Enabled = False
Command3.Enabled = False
Command4.Enabled = False
End If
End Sub

Private Sub Command2_Click()
Timer1.Enabled = True

If objDMSeg Is Nothing Then
MsgBox ("没有可以播放的MIDI文件，请先打开一个MIDI文件")
Exit Sub
End If

If fIsPaused Then '当前处于暂停状态
'获得暂停位置
Offset = lMTime - GetStartTime + Offset + 1
'设置开始播放点为暂停位置
Call objDMSeg.SetStartPoint(Offset)
'播放MIDI
Set objDMSegSt = objDMPerf.PlaySegment(objDMSeg, 0, 0)
fIsPaused = False
Sleep (90)
Else
Offset = 0
If objDMPerf.IsPlaying(objDMSeg, objDMSegSt) = True Then
'停止播放
Call objDMPerf.Stop(objDMSeg, objDMSegSt, 0, 0)
End If
objDMSeg.SetStartPoint (0)
Set objDMSegSt = objDMPerf.PlaySegment(objDMSeg, 0, 0)
Sleep (90)
End If
Command2.Enabled = False
Command3.Enabled = True
Command4.Enabled = True
End Sub

Private Sub Command3_Click()
On Error GoTo LocalErrors

If objDMSeg Is Nothing Then Exit Sub

If objDMPerf.IsPlaying(objDMSeg, objDMSegSt) = True Then
fIsPaused = True
'获得已经播放的长度
lMTime = objDMPerf.GetMusicTime()
GetStartTime = objDMSegSt.GetStartTime()
Call objDMPerf.Stop(objDMSeg, Nothing, 0, 0)
End If
Command2.Enabled = True
Command3.Enabled = False
Command4.Enabled = False
Exit Sub
LocalErrors:
Call Err.Raise(Err.Number, Err.Source, Err.Description)
End Sub

Private Sub Command4_Click()
If objDMSeg Is Nothing Then
Exit Sub
End If

fIsPaused = False
'停止播放MIDI文件
Call objDMPerf.Stop(objDMSeg, objDMSegSt, 0, 0)
End Sub

Private Sub Form_Load()
Me.Show

'建立DirectMusicLoader对象
Set objDMLoader = objDX.DirectMusicLoaderCreate
'建立DirectMusicPerformance对象
Set objDMPerf = objDX.DirectMusicPerformanceCreate
'初始化DirectMusicPerformance对象
objDMPerf.Init Nothing, 0
objDMPerf.SetPort -1, 80
objDMPerf.SetMasterAutoDownload (True)
objDMPerf.SetMasterVolume (-700)

Command1.Caption = "打开MIDI文件"
Command2.Caption = "播放"
Command3.Caption = "暂停"
Command4.Caption = "停止"
Command2.Enabled = False
Command3.Enabled = False
Command4.Enabled = False
Label1.Caption = ""
Label2.Caption = ""
Label3.Caption = ""
Timer1.Interval = 100
Timer1.Enabled = False
End Sub

Private Sub Form_Unload(Cancel As Integer)
Set objDMSegSt = Nothing
Set objDMSeg = Nothing
Set objDMPerf = Nothing
Set objDMLoader = Nothing
End
End Sub

Private Sub Timer1_Timer()
GetTimePassed
Label1.Caption = "MIDI播放时间：" + ElapsedTime + " 总时间：" + sAllTime
End Sub
　　运行程序，点击"打开MIDI文件"文件按钮打开一个MIDI文件，点击"播放"按钮播放文件，点击"暂停"按钮暂停播放，点击"停止"按钮停止播放。

　　上面的程序比较的简单，我就不做讲解了，大家可以自己分析。

　　由于DirectX编程是绕开了操作系统而直接对硬件进行操作，所以在编程过程中一定要比较的小心谨慎，由于Windows2000提供了对于DirectX的支持，如果有可能的化最好在Windows2000下编写，上面的程序就是我在Windows2000下编写运行调试后再在Windows98下检验的。并另外硬件对于程序的影响很大，上面的程序在你的机器上运行可能会有速度上的问题，我的机器配置是：赛扬500，128M内存，VooDoo3000, Yamaha 724声卡。