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首页 - 经验之谈 - 用VB做多媒体程序播放程序
发表评论(0)作者:不详, 平台:VB6.0+Win98, 阅读:9895, 日期:2001-05-06
用VB做多媒体程序播放程序

作者:TrueZq 中国软件开发中心



 已经有好多朋友问过诸如:
“如何播放Avi、Wave、midi文件”、:
“谁知道用api播放avi,mpg的详细方法?要可以设定将图像放置到设定的窗体中”、
“如何同时播放两个Wav文件”
的问题,其实用一个类模块就一切搞定,不需要什么控件之类的东西,下面这个类模块(不知从哪里找来的),我研究后将它修改得更好用了,将下面这个类模块存为Mmedia.cls
注释:----------------------------------------------------
Option Explicit

注释:--------------TrueZq 最新更新2001-01-12---------------------
注释:文件名: MMedia.cls
注释:说明: : 一个多媒体类,能播放Avi、Wave、Midi文件
注释:用法:
注释:Dim Multimedia As New Mmedia
注释:Multimedia.mmOpen "c:\test.wav"
注释:Multimedia.mmPlay
注释:!记住:在程序结束时,一定要用Set Multimedia=nothing释放资源!!!
注释:-----------------------------------------------------

注释: -=-=-=- 属性 -=-=-=-
注释: sFilename 当前的文件名
注释: nLength 文件长度(只读)
注释: nPosition 当前位置
注释: sStatus 当前状态(只读)
注释: bWait True/False.决定是否等待播放完

注释: -=-=-=- 方法 -=-=-=-=-
注释: mmOpen <Filename> 打开要播放的文件
注释: mmClose 关闭当前文件
注释: mmPause 暂停
注释: mmStop 停止 停止后可以跳到开始再次播放
注释: mmSeek <Position> Seeks to a position in the file
注释: mmPlay 播放

注释:--------------------------------------------------------------

Private sAlias As String 注释:别名
注释:Private hWnd As Long
Private sFilename As String 注释: 当前的文件名
Private nLength As Single 注释: 文件长度

Private nPosition As Single 注释: 当前位置
Private sStatus As String 注释: 当前状态
Private bWait As Boolean 注释: 决定是否等待播放完
Const WS_CHILD = &H40000000
注释:------------ API 声明 -------------
Private Declare Function mciSendString Lib "winmm.dll" _
Alias "mciSendStringA" (ByVal lpstrCommand As String, _
ByVal lpstrReturnString As String, ByVal uReturnLength As Long, _
ByVal hwndCallback As Long) As Long

注释:Private Declare Function GetActiveWindow Lib "USER32" () As Integer

注释:当sTheFile是一个Avi文件时,参数hWnd指定动画在哪里播放
注释:若hWnd=0,则新开一个窗口播放动画。
注释:如果听不到Midi音乐,请在Windows下用媒体播放器测试一下。
注释:文件名不能带空格
Public Sub mmOpen(ByVal sTheFile As String, Optional hWnd As Long = 0)

Dim nReturn As Long
Dim sType As String 注释:文件类型
Static nNum As Integer

If sAlias <> "" Then 注释:关闭开始打开的文件
mmClose
End If

If (Dir(sTheFile) = "") Then 注释:判断是否是一个存在的文件
sFilename = "文件" & sTheFile & " 不存在!"
Exit Sub
Else
sFilename = sTheFile
注释: nNum = nNum + 1
End If
注释: Stop
sAlias = sFilename 注释:用文件名作别名,避免别名冲突!
注释: 判断文件类型
Select Case UCase$(Right$(sTheFile, 3))
Case "WAV"
sType = "Waveaudio"
Case "AVI"
sType = "AviVideo"

Case "MID"
sType = "Sequencer"
Case Else
注释: 未知文件格式,退出。
Exit Sub
End Select

If sType = "AviVideo" And hWnd > 0 Then
nReturn = mciSendString("open " & sTheFile & " ALIAS " & sAlias _
& " TYPE AVIVideo parent " & hWnd & " style " & LTrim$(Str$(WS_CHILD)), 0&, 0, 0)
Else
nReturn = mciSendString("Open " & sTheFile & " ALIAS " & sAlias _
& " TYPE " & sType, "", 0, 0)
End If

End Sub

注释:关闭当前打开的多媒体文件
Public Sub mmClose()
Dim nReturn As Long

注释:如果没有文件打开,则退出
If sAlias = "" Then Exit Sub

nReturn = mciSendString("Close " & sAlias, "", 0, 0)
sAlias = ""
sFilename = ""

End Sub

注释:暂停
Public Sub mmPause()

Dim nReturn As Long

If sAlias = "" Then
Exit Sub
ElseIf Status = "paused" Then 注释:如果先前已经暂停了,则解除暂停
mmPlay
Else
nReturn = mciSendString("Pause " & sAlias, "", 0, 0)
End If
注释:nPosition = Position
End Sub

注释:播放
Public Sub mmPlay()

Dim nReturn As Long

If sAlias = "" Then
Exit Sub
ElseIf Position = Length Then 注释:如果已经到末尾
mmSeek 0 注释:跳到开始处
End If


If bWait Then
nReturn = mciSendString("Play " & sAlias & " wait", "", 0, 0)
Else
nReturn = mciSendString("Play " & sAlias, "", 0, 0)
End If
End Sub

注释:停止
注释:停止后跳到开始,以便再次播放
Public Sub mmStop()

Dim nReturn As Long

If sAlias = "" Then Exit Sub

nReturn = mciSendString("Stop " & sAlias, "", 0, 0)
mmSeek 0 注释:跳到开始位置
End Sub

注释:跳到指定的位置,并且处于暂停状态
注释:当nPosition的值>Length 或者nPosition<0时,将忽略这次操作
Public Sub mmSeek(ByVal nPosition As Single)

Dim nReturn As Long
nReturn = mciSendString("Seek " & sAlias & " to " & nPosition, "", 0, 0)

End Sub

注释:方法Filename返回当前打开的文件名
Property Get filename() As String
filename = sFilename
End Property

注释:指定要播放的文件名,然后将它打开
注释:对于需要指定容器的Avi文件,不要以这种方式打开。
Property Let filename(ByVal sTheFile As String)

mmOpen sTheFile
End Property

注释:读取属性Wait的值
注释:Msgbox Multimedia.Wait
Property Get Wait() As Boolean
Wait = bWait
End Property

注释:设置等待属性
注释:用法:Multimedia.Wait=True
Property Let Wait(bWaitValue As Boolean)

bWait = bWaitValue
End Property

注释:获得长度值
Property Get Length() As Single

Dim nReturn As Long, nLength As Integer

Dim sLength As String * 255

If sAlias = "" Then
Length = 0
Exit Property
End If

nReturn = mciSendString("Status " & sAlias & " length", sLength, 255, 0)
nLength = InStr(sLength, Chr$(0))
Length = Val(Left$(sLength, nLength - 1))
End Property

Property Let Position(ByVal nPosition As Single)
mmSeek nPosition
End Property

注释:获取当前位置
Property Get Position() As Single

Dim nReturn As Integer, nLength As Integer

Dim sPosition As String * 255

If sAlias = "" Then Exit Property


nReturn = mciSendString("Status " & sAlias & " position", sPosition, 255, 0)
nLength = InStr(sPosition, Chr$(0))
Position = Val(Left$(sPosition, nLength - 1))

End Property

注释:当前打开文件的状态
注释:有以下几种:playing paused stopped
Property Get Status() As String

Dim nReturn As Integer, nLength As Integer
Dim sStatus As String * 255


If sAlias = "" Then Exit Property

nReturn = mciSendString("Status " & sAlias & " mode", sStatus, 255, 0)

nLength = InStr(sStatus, Chr$(0))
Status = Left$(sStatus, nLength - 1)

End Property

注释:从头开始播放
Public Sub mmRestart()
Dim nReturn As Long

If sAlias = "" Then Exit Sub

mmSeek 0
mmPlay
End Sub

注释:类的初始化
Private Sub Class_Initialize()
注释: sAlias = "" 注释:别名初值为空
End Sub

注释:关闭打开的多媒体设备
注释:当该类的对象所在的窗体(或模块)卸载时,自动调用该过程
Private Sub Class_Terminate()
mmClose
End Sub
注释:----------------------------------------------------
[用法]
1、
比如要在窗体上播放一个动画,只需3个语句就搞定。
Dim MmAvi As New Mmedia
MmAvi.mmOpen "G:\resource\Avi\Test.avi", Me.hWnd
MmAvi.mmPlay

2、循环播放
Private Sub Timer1_Timer()
Dim S As String
S = "当前文件:" & MmAvi.filename & vbCrLf & "当前位置:" & MmAvi.Position _
& "总长度:" & MmAvi.Length & "当前状态:" & MmAvi.Status
Label1.Caption = S
If MmAvi.Status = "stopped" Then MmAvi.mmRestart
End sub

3、同时播放几个文件(类型可以相同、可以不同)
在Form1中加入Private MmWave(1) As New Mmedia
在需要播放的地方加上:
MmWave(0).mmOpen "G:\resource\wave\m16.wav"
MmWave(1).mmOpen "G:\resource\wave\Welcom98.wav"
MmWave(0).mmPlay
MmWave(1).mmPlay
4、将动画放入一个圆形区域播放

Dim hr As Long
Dim usew&, useh&
Dim MmAvi As New Mmedia

usew& = Frame1.Width / Screen.TwipsPerPixelX
useh& = Frame1.Height / Screen.TwipsPerPixelY
usew = useh
hr& = CreateEllipticRgn(0, 0, usew, useh)
Call SetWindowRgn(Frame1.hWnd, hr, True)
MmAvi.mmOpen "G:\resource\Avi\start.avi", Frame1.hWnd
MmAvi.mmPlay
………………………………