请问哪位大虾知道怎样控制系统中音量的大小？

Question

使用Mixer控制
电脑编程技巧与维护的2000年3月版有很详细的东东

Answer 1

用多媒体API创建，然后发送一个相关命令，到MSDN上找吧

Answer 2

在WINDOWS中有相应的API函数可供调用。叫什么MIX...的吧。

Answer 3

设置音量的程序      DWORD lr;
    MMRESULT k1;
    UINT cbmxctrls;
    HMIXER phmx;
    UINT mixID;
    MIXERLINE mxl;
    MIXERLINECONTROLS pmxlc;
    PMIXERCONTROL pmxlc1;
    MIXERCONTROLDETAILS pmxcd;
    MIXERCONTROLDETAILS_UNSIGNED  Volume;
    DWORD dSource;
    DWORD i;
    
    // Record Volume
    k1=::mixerGetID(0,&mixID,MIXER_OBJECTF_HMIXER);
    if (k1!=MMSYSERR_NOERROR)
        return;
    // MixerOpen
    k1=::mixerOpen(&phmx,mixID,NULL,NULL,MIXER_OBJECTF_HMIXER);
    if (k1!=MMSYSERR_NOERROR)
        return;
    // MixerGetLineInfo
    mxl.cbStruct=sizeof(MIXERLINE);
    mxl.dwDestination=1;
    k1=::mixerGetLineInfo(0,&mxl,MIXER_GETLINEINFOF_DESTINATION);
    if (k1!=MMSYSERR_NOERROR)
        return;
    lr=mxl.dwLineID; 
    // MixergetLineInfo
    DWORD dConnections;
    dConnections=mxl.cConnections;
    for ( dSource=0 ; dSource<=dConnections ; dSource++)
    {
      mxl.dwSource=dSource; //4
      k1=::mixerGetLineInfo(0, &mxl, MIXER_GETLINEINFOF_SOURCE);
      lr=mxl.dwLineID; 
    
      // --- MixerGetLineControls
      cbmxctrls = sizeof(*pmxlc1) * (UINT)mxl.cControls;
      pmxlc1 = (PMIXERCONTROL)LocalAlloc(LPTR, cbmxctrls);
      pmxlc.cbStruct=sizeof(pmxlc);
      pmxlc.cControls=mxl.cControls;
      pmxlc.cbmxctrl=sizeof(*pmxlc1);
      pmxlc.pamxctrl=pmxlc1;
      pmxlc.dwLineID=lr;//0;//MIXER_GETLINECONTROLSF_ONEBYID;  
      //pmxlc.dwControlType=MIXER_GETLINECONTROLSF_ONEBYTYPE;
      //pmxlc.dwControlID =13;
      k1=::mixerGetLineControls(0,&pmxlc,MIXER_GETLINECONTROLSF_ALL);//MIXER_GETLINECONTROLSF_ONEBYID);//MIXER_GETLINECONTROLSF_ONEBYID&brvbar;MIXER_OBJECTF_HMIXER);
      // MixerGetControlDetails
      /*
      for ( i=0 ; i < pmxlc.cControls ;i++)
      {
        if ( pmxlc1[i].dwControlType==MIXERCONTROL_CONTROLTYPE_MUTE)
            break;      }*/
      //6/30 volum============
      pmxcd.cbStruct=sizeof(MIXERCONTROLDETAILS);
      pmxcd.dwControlID=pmxlc1[0].dwControlID;
      pmxcd.cChannels=1;
      pmxcd.hwndOwner=0;
      pmxcd.cbDetails=sizeof(Volume);
      pmxcd.paDetails=&Volume;
      k1=::mixerGetControlDetails(0,&pmxcd,MIXER_OBJECTF_WAVEOUT);//MIXER_GETCONTROLDETAILSF_VALUE);//&brvbar;MIXER_OBJECTF_WAVEOUT);
      // MixerSetControlDetails
      Volume.dwValue=uVolume;
      //k1=::mixerGetControlDetails(0,&pmxcd,0L);//MIXER_OBJECTF_WAVEOUT) // for test
      k1=::mixerSetControlDetails(0,&pmxcd,0L);//MIXER_OBJECTF_WAVEOUT)
      
      // MixerClose
    }
    k1=::mixerClose(phmx);    // Play Volume
    k1=::mixerGetID(0,&mixID,MIXER_OBJECTF_HMIXER);
    if (k1!=MMSYSERR_NOERROR)
        return;
    // MixerOpen
    k1=::mixerOpen(&phmx,mixID,NULL,NULL,MIXER_OBJECTF_HMIXER);
    if (k1!=MMSYSERR_NOERROR)
        return;
    // MixerGetLineInfo
    mxl.cbStruct=sizeof(MIXERLINE);
    mxl.dwDestination=0;
    k1=::mixerGetLineInfo(0,&mxl,MIXER_GETLINEINFOF_DESTINATION);
    if (k1!=MMSYSERR_NOERROR)
        return;
    lr=mxl.dwLineID; 
    // --- MixerGetLineInfo
    mxl.cbStruct=sizeof(MIXERLINE);
    mxl.dwLineID=lr;
    k1=::mixerGetLineInfo(0,&mxl,MIXER_GETLINEINFOF_LINEID);
    // --- MixerGetLineControls
    cbmxctrls = sizeof(*pmxlc1) * (UINT)mxl.cControls;
    pmxlc1 = (PMIXERCONTROL)LocalAlloc(LPTR, cbmxctrls);
    pmxlc.cbStruct=sizeof(pmxlc);
    pmxlc.cControls=mxl.cControls;
    pmxlc.cbmxctrl=sizeof(*pmxlc1);
    pmxlc.pamxctrl=pmxlc1;
    pmxlc.dwLineID=lr;
    k1=::mixerGetLineControls(0,&pmxlc,MIXER_GETLINECONTROLSF_ALL);
    // MixerGetControlDetails
    for ( i=0 ; i < pmxlc.cControls ;i++)
    {
        if ( pmxlc1[i].dwControlType==MIXERCONTROL_CONTROLTYPE_VOLUME)
            break;    }
    pmxcd.cbStruct=sizeof(MIXERCONTROLDETAILS);
    pmxcd.dwControlID=pmxlc1[i].dwControlID;
    pmxcd.cChannels=1;
    pmxcd.hwndOwner=0;
    pmxcd.cbDetails=sizeof(Volume);
    pmxcd.paDetails=&Volume;
    k1=::mixerGetControlDetails(0,&pmxcd,MIXER_OBJECTF_WAVEOUT);//MIXER_GETCONTROLDETAILSF_VALUE);//&brvbar;MIXER_OBJECTF_WAVEOUT);
      // MixerSetControlDetails
    Volume.dwValue=uVolume;
    k1=::mixerSetControlDetails(0,&pmxcd,0L);//MIXER_OBJECTF_WAVEOUT)
      // MixerClose
    k1=::mixerClose(phmx);