UInt32 size;

    AudioDeviceID outputDevice;

    AudioHardwareGetProperty(kAudioHardwarePropertyDefaultOutputDevice,

                                              &size,

                                              &outputDevice);

bool CAAudioHardwareDevice::HasProperty(

    UInt32 inChannel,

    CAAudioHardwareDeviceSectionID inSection,

    AudioHardwarePropertyID inPropertyID) const

{

    OSStatus theError = AudioDeviceGetPropertyInfo(mAudioDeviceID,

            inChannel, inSection, inPropertyID, NULL, NULL);

    return theError == 0;

}

bool CAAudioHardwareDevice::PropertyIsSettable(

    UInt32 inChannel,

    CAAudioHardwareDeviceSectionID inSection,

    AudioHardwarePropertyID inPropertyID) const

{

    Boolean isWritable = false;

    OSStatus theError = AudioDeviceGetPropertyInfo(mAudioDeviceID, inChannel,

        inSection, inPropertyID, NULL, &isWritable);

    ThrowIfError(theError, CAException(theError),

        "CAAudioHardwareDevice::PropertyIsSettable: got "

        "an error getting info about a property");

    return isWritable != 0;

}

bool CAAudioHardwareDevice::HasVolumeControl(

    UInt32 inChannel,

    CAAudioHardwareDeviceSectionID inSection) const

{

    return HasProperty(inChannel, inSection, kAudioDevicePropertyVolumeScalar);

}

bool CAAudioHardwareDevice::VolumeControlIsSettable(

    UInt32 inChannel,

    CAAudioHardwareDeviceSectionID inSection) const

{

    return PropertyIsSettable(inChannel, inSection, kAudioDevicePropertyVolumeScalar);

}

AudioDeviceSetProperty(theDevice,

                         NULL, //time stamp not needed

                         0, //channel 0 is master channel

                         false,  //for an output device

                         kAudioDevicePropertyVolumeScalar,

                         sizeof(Float32),

                         &theValue );