关于音量控制的问题

Question

怎样编程才能达到这样的效果：无论怎样调音量图标里volume的滑杆，系统音量只能限定在指定的一个范围内？即改变系统最大音量值

Answer 1

看看《windows 程序设计》第二十二章 里面有详细的关于这方面的东东/

Answer 2

你看一下下面这篇文章，应该帮助会很大的：
http://asp.6to23.com/nowcan/tech/cb_volume.htm

Answer 3

你看看这里有：Audio Mixer Functions are a set of functions that control the routing of audio lines to a destination device for playing or recording. They can also control volume and other effects.http://www.codeproject.com/audio/admixer.asp?target=volume%7Csound

Answer 4

多写个判断就可以了啊：const long m_vconstMax=4000;
const long m_vconstMin=-4000;
long m_valume= volumeEdit.GetVolume ();if(m_valume>m_vconstMax)
{
    m_valume=m_vconstMax;
}if( m_valume<m_vconstMin)
{
    m_valume=m_vconstMin
} 
  
    MyWinamp.Pause ();     MyWinamp.SetVolume(m_valume); 
 
    MyWinamp.Run (); 

Answer 5

给焦急等待的人的福音，两个函数一看就明白了：
(要include "mmsystem.h"和link "winmm.lib")void CVolumeDlg::SetVolume( const DWORD dwVolume )
{
    MMRESULT                        result;
    HMIXER                          hMixer;
    MIXERLINE                       ml   = {0};
    MIXERLINECONTROLS               mlc  = {0};
    MIXERCONTROL                    mc   = {0};
    MIXERCONTROLDETAILS             mcd  = {0};
    MIXERCONTROLDETAILS_UNSIGNED    mcdu = {0};
    // get a handle to the mixer device
    result = mixerOpen(&hMixer, MIXER_OBJECTF_MIXER, 0, 0, 0);
    if (MMSYSERR_NOERROR == result)
    {
        ml.cbStruct        = sizeof(MIXERLINE);
        ml.dwComponentType = MIXERLINE_COMPONENTTYPE_DST_SPEAKERS;        // get the speaker line of the mixer device
        result = mixerGetLineInfo((HMIXEROBJ) hMixer, &ml, MIXER_GETLINEINFOF_COMPONENTTYPE);
        if (MMSYSERR_NOERROR == result)
        {
            mlc.cbStruct      = sizeof(MIXERLINECONTROLS);
            mlc.dwLineID      = ml.dwLineID;
            mlc.dwControlType = MIXERCONTROL_CONTROLTYPE_VOLUME;
            mlc.cControls     = 1;
            mlc.pamxctrl      = &mc;
            mlc.cbmxctrl      = sizeof(MIXERCONTROL);            // get the volume controls associated with the speaker line
            result = mixerGetLineControls((HMIXEROBJ) hMixer, &mlc, MIXER_GETLINECONTROLSF_ONEBYTYPE);
            if (MMSYSERR_NOERROR == result)
            {
                mcdu.dwValue    = dwVolume;                mcd.cbStruct    = sizeof(MIXERCONTROLDETAILS);
                mcd.hwndOwner   = 0;
                mcd.dwControlID = mc.dwControlID;
                mcd.paDetails   = &mcdu;
                mcd.cbDetails   = sizeof(MIXERCONTROLDETAILS_UNSIGNED);
                mcd.cChannels   = 1;                // set the volume
                result = mixerSetControlDetails((HMIXEROBJ) hMixer, &mcd, MIXER_SETCONTROLDETAILSF_VALUE);
                if (MMSYSERR_NOERROR == result)
                    AfxMessageBox("Volume changed!");
                else
                    AfxMessageBox("mixerSetControlDetails() failed");
            }
            else
                AfxMessageBox("mixerGetLineControls() failed");
        }
        else
            AfxMessageBox("mixerGetLineInfo() failed");
    
        mixerClose(hMixer);
    }
    else
        AfxMessageBox("mixerOpen() failed");
}//====================================================================DWORD CVolumeDlg::GetVolume( void )
{
    DWORD                           dwVolume = -1;
    MMRESULT                        result;
    HMIXER                          hMixer;
    MIXERLINE                       ml   = {0};
    MIXERLINECONTROLS               mlc  = {0};
    MIXERCONTROL                    mc   = {0};
    MIXERCONTROLDETAILS             mcd  = {0};
    MIXERCONTROLDETAILS_UNSIGNED    mcdu = {0};
    // get a handle to the mixer device
    result = mixerOpen(&hMixer, 0, 0, 0, MIXER_OBJECTF_HMIXER);
    if (MMSYSERR_NOERROR == result)
    {
        ml.cbStruct        = sizeof(MIXERLINE);
        ml.dwComponentType = MIXERLINE_COMPONENTTYPE_DST_SPEAKERS;        // get the speaker line of the mixer device
        result = mixerGetLineInfo((HMIXEROBJ) hMixer, &ml, MIXER_GETLINEINFOF_COMPONENTTYPE);
        if (MMSYSERR_NOERROR == result)
        {
            mlc.cbStruct      = sizeof(MIXERLINECONTROLS);
            mlc.dwLineID      = ml.dwLineID;
            mlc.dwControlType = MIXERCONTROL_CONTROLTYPE_VOLUME;
            mlc.cControls     = 1;
            mlc.pamxctrl      = &mc;
            mlc.cbmxctrl      = sizeof(MIXERCONTROL);            // get the volume controls associated with the speaker line
            result = mixerGetLineControls((HMIXEROBJ) hMixer, &mlc, MIXER_GETLINECONTROLSF_ONEBYTYPE);
            if (MMSYSERR_NOERROR == result)
            {
                mcd.cbStruct    = sizeof(MIXERCONTROLDETAILS);
                mcd.hwndOwner   = 0;
                mcd.dwControlID = mc.dwControlID;
                mcd.paDetails   = &mcdu;
                mcd.cbDetails   = sizeof(MIXERCONTROLDETAILS_UNSIGNED);
                mcd.cChannels   = 1;                // get the volume
                result = mixerGetControlDetails((HMIXEROBJ) hMixer, &mcd, MIXER_SETCONTROLDETAILSF_VALUE);
                if (MMSYSERR_NOERROR == result)
                    dwVolume = mcdu.dwValue;
                else
                    AfxMessageBox("mixerGetControlDetails() failed");
            }
            else
                AfxMessageBox("mixerGetLineControls() failed");
        }
        else
            AfxMessageBox("mixerGetLineInfo() failed");
    
        mixerClose(hMixer);
    }
    else
        AfxMessageBox("mixerOpen() failed");    return (dwVolume);
}