我做的MCI音频，在音量大小遇到难题！大哥大姐们来帮帮我（急）

[LoginOn]

如题
我在Create的时候已经给了设备名称为 myMedia

调节音量时我用的是 mciSendString("setaudio myMedia volume to 2",NULL,0,NULL);

最后音量也不变哦！

我是第一次用MCI，已经弄了半天了，这个问题也没解决！
来救命~~~~~~~

[wanbotang]

它能认识你那个字符串吗？你用的是控件还是API啊？

[LoginOn]

我用的是API
我用mciSendString已经实现了 播放。暂停等操作了

但是一用个这个字符串，就提示“驱动程序无法识别指定的命令”

[wanbotang]

别人的代码，看看吧

Option Explicit

Private hmem As Long

Const MMSYSERR_NOERROR = 0
Const MAXPNAMELEN = 32
Const MIXER_LONG_NAME_CHARS = 64
Const MIXER_SHORT_NAME_CHARS = 16
Const MIXER_GETLINEINFOF_COMPONENTTYPE = &H3&
Const MIXER_GETCONTROLDETAILSF_VALUE = &H0&
Const MIXER_SETCONTROLDETAILSF_VALUE = &H0&
Const MIXER_GETLINECONTROLSF_ONEBYTYPE = &H2&
Const MIXERLINE_COMPONENTTYPE_DST_FIRST = &H0&
Const MIXERLINE_COMPONENTTYPE_SRC_FIRST = &H1000&
Const MIXERLINE_COMPONENTTYPE_DST_SPEAKERS = _
(MIXERLINE_COMPONENTTYPE_DST_FIRST + 4)
Const MIXERLINE_COMPONENTTYPE_SRC_MICROPHONE = _
(MIXERLINE_COMPONENTTYPE_SRC_FIRST + 3)
Const MIXERLINE_COMPONENTTYPE_SRC_LINE = _
(MIXERLINE_COMPONENTTYPE_SRC_FIRST + 2)
Const MIXERCONTROL_CT_CLASS_FADER = &H50000000
Const MIXERCONTROL_CT_UNITS_UNSIGNED = &H30000
Const MIXERCONTROL_CONTROLTYPE_FADER = _
(MIXERCONTROL_CT_CLASS_FADER Or _
MIXERCONTROL_CT_UNITS_UNSIGNED)
Const MIXERCONTROL_CONTROLTYPE_VOLUME = _
(MIXERCONTROL_CONTROLTYPE_FADER + 1)

Private Type MIXERCONTROLDETAILS
cbStruct As Long
dwControlID As Long
cChannels As Long
item As Long
cbDetails As Long
paDetails As Long
End Type

Private Type MIXERCONTROLDETAILS_UNSIGNED
dwValue As Long
End Type

[wanbotang]

Private Type MIXERCONTROL
cbStruct As Long
dwControlID As Long
dwControlType As Long
fdwControl As Long
cMultipleItems As Long
szShortName As String * MIXER_SHORT_NAME_CHARS
szName As String * MIXER_LONG_NAME_CHARS
lMinimum As Long
lMaximum As Long
reserved(10) As Long
End Type

Private Type MIXERLINECONTROLS
cbStruct As Long
dwLineID As Long
dwControl As Long
cControls As Long
cbmxctrl As Long
pamxctrl As Long
End Type

Private Type MIXERLINE
cbStruct As Long
dwDestination As Long
dwSource As Long
dwLineID As Long
fdwLine As Long
dwUser As Long
dwComponentType As Long
cChannels As Long
cConnections As Long
cControls As Long
szShortName As String * MIXER_SHORT_NAME_CHARS
szName As String * MIXER_LONG_NAME_CHARS
dwType As Long
dwDeviceID As Long
wMid As Integer
wPid As Integer
vDriverVersion As Long
szPname As String * MAXPNAMELEN
End Type
'
'Allocates the specified number of bytes from the heap.
Private Declare Function GlobalAlloc Lib "kernel32" (ByVal wFlags As Long, _
ByVal dwBytes As Long) As Long
'
'Locks a global memory object and returns a pointer to the
' first byte of the object's memory block. The memory block
' associated with a locked object cannot be moved or discarded.
Private Declare Function GlobalLock Lib "kernel32" (ByVal hmem As Long) As Long
'
'Frees the specified global memory object and invalidates its handle.
Private Declare Function GlobalFree Lib "kernel32" (ByVal hmem As Long) As Long
'
Private Declare Sub CopyPtrFromStruct Lib "kernel32" Alias "RtlMoveMemory" _
(ByVal ptr As Long, struct As Any, ByVal cb As Long)

Private Declare Sub CopyStructFromPtr Lib "kernel32" Alias "RtlMoveMemory" _
(struct As Any, ByVal ptr As Long, ByVal cb As Long)
'
'Opens a specified mixer device and ensures that the device
' will not be removed until the application closes the handle.
Private Declare Function mixerOpen Lib "winmm.dll" _
(phmx As Long, ByVal uMxId As Long, ByVal dwCallback As Long, _
ByVal dwInstance As Long, ByVal fdwOpen As Long) As Long
'
'Sets properties of a single control associated with an audio line.
Private Declare Function mixerSetControlDetails Lib "winmm.dll" _
(ByVal hmxobj As Long, pmxcd As MIXERCONTROLDETAILS, _
ByVal fdwDetails As Long) As Long
'
'Retrieves information about a specific line of a mixer device.
Private Declare Function mixerGetLineInfo Lib "winmm.dll" _
Alias "mixerGetLineInfoA" (ByVal hmxobj As Long, _
pmxl As MIXERLINE, ByVal fdwInfo As Long) As Long
'
'Retrieves one or more controls associated with an audio line.
Private Declare Function mixerGetLineControls Lib "winmm.dll" _
Alias "mixerGetLineControlsA" (ByVal hmxobj As Long, _
pmxlc As MIXERLINECONTROLS, ByVal fdwControls As Long) As Long

Private hmixer As Long
Private volCtrl As MIXERCONTROL ' Waveout volume control.
Private micCtrl As MIXERCONTROL ' Microphone volume control.
'
'Local variable to save properties
Private mvarprMicVolume As Long 'Local copy
Private mvarprMicMaxVolume As Long 'Local copy
Private mvarprMicMinVolume As Long 'Local copy
Private mvarprSpeakerVolume As Long 'Local copy
Private mvarprSpeakerMaxVolume As Long 'Local copy
Private mvarprSpeakerMinVolume As Long 'Local copy
Private mvarprMixerErr As Long 'Local copy

Private Function fGetVolumeControl(ByVal hmixer As Long, _
ByVal componentType As Long, ByVal ctrlType As Long, _
ByRef mxc As MIXERCONTROL) As Boolean
'
' This function attempts to obtain a mixer control.
'
Dim mxlc As MIXERLINECONTROLS
Dim mxl As MIXERLINE
Dim hmem As Long
Dim rc As Long

mxl.cbStruct = Len(mxl)
mxl.dwComponentType = componentType
'
' Get a line corresponding to the component type.
'
rc = mixerGetLineInfo(hmixer, mxl, MIXER_GETLINEINFOF_COMPONENTTYPE)
If MMSYSERR_NOERROR = rc Then
With mxlc
.cbStruct = Len(mxlc)
.dwLineID = mxl.dwLineID
.dwControl = ctrlType
.cControls = 1
.cbmxctrl = Len(mxc)
End With
'
' Allocate a buffer for the control.
'
hmem = GlobalAlloc(&H40, Len(mxc))
mxlc.pamxctrl = GlobalLock(hmem)
mxc.cbStruct = Len(mxc)
'
' Get the control.
'
rc = mixerGetLineControls(hmixer, mxlc, MIXER_GETLINECONTROLSF_ONEBYTYPE)
If MMSYSERR_NOERROR = rc Then
fGetVolumeControl = True
'
' Copy the control into the destination structure.
'
Call CopyStructFromPtr(mxc, mxlc.pamxctrl, Len(mxc))
Else
fGetVolumeControl = False
End If
Call GlobalFree(hmem)
Exit Function
End If
fGetVolumeControl = False
End Function

[wanbotang]

Private Function fSetVolumeControl(ByVal hmixer As Long, _
mxc As MIXERCONTROL, ByVal volume As Long) As Boolean
'
' This function sets the value for a volume control.
'
Dim rc As Long
Dim mxcd As MIXERCONTROLDETAILS
Dim vol As MIXERCONTROLDETAILS_UNSIGNED

With mxcd
.item = 0
.dwControlID = mxc.dwControlID
.cbStruct = Len(mxcd)
.cbDetails = Len(vol)
End With
'
' Allocate a buffer for the control value buffer.
'
hmem = GlobalAlloc(&H40, Len(vol))
mxcd.paDetails = GlobalLock(hmem)
mxcd.cChannels = 1
vol.dwValue = volume
'
' Copy the data into the control value buffer.
'
Call CopyPtrFromStruct(mxcd.paDetails, vol, Len(vol))
'
' Set the control value.
'
rc = mixerSetControlDetails(hmixer, mxcd, MIXER_SETCONTROLDETAILSF_VALUE)
Call GlobalFree(hmem)

If MMSYSERR_NOERROR = rc Then
fSetVolumeControl = True
Else
fSetVolumeControl = False
End If
End Function

Public Function meOpenMixer() As Long
Dim rc As Long
Dim bOK As Boolean
'
' Open the mixer with deviceID 0.
'
rc = mixerOpen(hmixer, 0, 0, 0, 0)
mvarprMixerErr = rc
If MMSYSERR_NOERROR <> rc Then
MsgBox "Could not open the mixer.", vbCritical, "Volume Control"
Exit Function
End If
'
' Get the waveout volume control.
'
bOK = fGetVolumeControl(hmixer, _
MIXERLINE_COMPONENTTYPE_DST_SPEAKERS, _
MIXERCONTROL_CONTROLTYPE_VOLUME, volCtrl)
'
' If the function successfully gets the volume control,
' the maximum and minimum values are specified by
' lMaximum and lMinimum.
'
If bOK Then
mvarprSpeakerMaxVolume = volCtrl.lMaximum
mvarprSpeakerMinVolume = volCtrl.lMinimum
End If
'
' Get the microphone volume control.
'
bOK = fGetVolumeControl(hmixer, _
MIXERLINE_COMPONENTTYPE_SRC_MICROPHONE, _
MIXERCONTROL_CONTROLTYPE_VOLUME, micCtrl)

If bOK Then
mvarprMicMaxVolume = micCtrl.lMaximum
mvarprMicMinVolume = micCtrl.lMinimum
End If
End Function

Public Property Get prMixerErr() As Long
prMixerErr = mvarprMixerErr
End Property

Public Property Get prSpeakerMinVolume() As Long
prSpeakerMinVolume = mvarprSpeakerMinVolume
End Property

Public Property Get prSpeakerMaxVolume() As Long
prSpeakerMaxVolume = mvarprSpeakerMaxVolume
End Property

Public Property Let prSpeakerVolume(ByVal vData As Long)
mvarprSpeakerVolume = vData
Call fSetVolumeControl(hmixer, volCtrl, vData)
End Property

Public Property Get prSpeakerVolume() As Long
prSpeakerVolume = mvarprSpeakerVolume
End Property

Public Property Get prMicMinVolume() As Long
prMicMinVolume = mvarprMicMinVolume
End Property

Public Property Get prMicMaxVolume() As Long
prMicMaxVolume = mvarprMicMaxVolume
End Property

Public Property Let prMicVolume(ByVal vData As Long)
mvarprMicVolume = vData
Call fSetVolumeControl(hmixer, micCtrl, vData)
End Property

Public Property Get prMicVolume() As Long
prMicVolume = mvarprMicVolume
End Property

<到这里完>

[LoginOn]

呵呵 你这个好象是用mixer实现的音频。有些不相符
不过还是谢谢了
今天晚上再等等看有没有好些的答案。下班了，明天来结贴！

THANKS

[LoginOn]

大哥大姐们一定要不吝赐教啊！！！

[homezj]

setaudio命令不是所有设备都会支持的，要看你播放的是什么内容，典型例子：它对Midi音乐就是无效的，但可用midiOutSetVolume调节

[LoginOn]

来了！
我播放的是.WAV文件 是不是设备对.wav的文件setaudio命令也不支持呢！

[homezj]

应该不能用在WAV文件上吧，我印象中setaudio只可用于Digital-video and VCR devices，它只是修改解码播放设备的音量，如Mp3、Wma等，不会改变系统音量，这些文件解码后基本都是WAV输出，所以它们还可能通过系统音量做二次调节，WAV文件是直接输出的，没有解码过程，只能通过改变系统音量来调节。

[homezj]

我的理解：利用MCI-API播放的软件只是一个功能外壳而已，根本称不上为播放器。能叫做的媒体播放器的软件，都是自己解码自已控制音频流输出最后才交给系统进行混音，而且很多一般都是支持或仅采用DirectSound方式输出音频，音量控制是独立于系统的也就很正常，前面说的setaudio命令，本质上也是调用相关设备的这种功能而已。

[LoginOn]

恩 这样就明白多了！我再想办法实现
结贴

[LoginOn]

哦！这样我就清楚多了
但是.wav文件如何控制音量大小呢？只能控制系统的音量？我用waveoutsetvolume倒是可以弄音量大小。这个只是修改系统的波形，如果象mediaplayer那样的音量大小调节是怎么实现的呢？
马上就结贴，大哥们再帮帮小弟我。

[whupyf]

但是我实验了一下.发现了问题.设置系统音量可以,但是不能获得系统音量