VC 关闭应用程序发出的声音

BOOL  SetMute( BOOL  bMute)
{
    HMIXER hMixer;
    MIXERCONTROL mxc;
    MIXERLINE mxl;
    MIXERLINECONTROLS mxlc;
    MIXERCONTROLDETAILS mxcd;
    MIXERCONTROLDETAILS_SIGNED volStruct;
    MMRESULT mmr;

    //Sound Setting
    mmr = mixerOpen(&hMixer, 0, 0, 0, 0);
    if  (mmr != MMSYSERR_NOERROR)  return  FALSE;

    // 初始化MIXERLINE结构体.
    ZeroMemory(&mxl,  sizeof (MIXERLINE));
    mxl.cbStruct =  sizeof (MIXERLINE);

    // 指出需要获取的通道，扬声器用MIXERLINE_COMPONENTTYPE_DST_SPEAKERS
    mxl.dwComponentType = MIXERLINE_COMPONENTTYPE_DST_SPEAKERS;

    mmr = mixerGetLineInfo((HMIXEROBJ)hMixer, &mxl, MIXER_GETLINEINFOF_COMPONENTTYPE);
    if  (mmr != MMSYSERR_NOERROR)  return  FALSE;

    // 取得控制器.
    ZeroMemory(&mxlc,  sizeof (MIXERLINECONTROLS));
    mxlc.cbStruct =  sizeof (MIXERLINECONTROLS);
    mxlc.dwLineID = mxl.dwLineID;
    mxlc.dwControlType = MIXERCONTROL_CONTROLTYPE_MUTE;
    mxlc.cControls = 1;
    mxlc.cbmxctrl =  sizeof (mxc);
    mxlc.pamxctrl = &mxc;
    //mxc.cMultipleItems=0;

    ZeroMemory(&mxc,  sizeof (MIXERCONTROL));
    mxc.cbStruct =  sizeof (MIXERCONTROL);
    mmr = mixerGetLineControls((HMIXEROBJ)hMixer, &mxlc, MIXER_GETLINECONTROLSF_ONEBYTYPE);
    if  (mmr != MMSYSERR_NOERROR)  return  FALSE;

    // 初始化MIXERCONTROLDETAILS结构体
    ZeroMemory(&mxcd,  sizeof (MIXERCONTROLDETAILS));
    mxcd.cbStruct =  sizeof (MIXERCONTROLDETAILS);
    mxcd.cbDetails =  sizeof (MIXERCONTROLDETAILS_SIGNED);
    mxcd.dwControlID = mxc.dwControlID;
    mxcd.paDetails = &volStruct;
    mxcd.cChannels = 1;

    // 获得音量值
    volStruct.lValue = bMute;
    mmr = mixerSetControlDetails((HMIXEROBJ)hMixer, &mxcd, MIXER_SETCONTROLDETAILSF_VALUE);

    mixerClose(hMixer);
    return  TRUE;
}