I have a small utility for monitoring Core Audio listener notifications on audio devices and streams using wildcard settings, e.g.:
Notification for DEVICE object (63) at Wed Jan 13 04:27:49 2016
kAudioDevicePropertyVolumeScalar ('volm'), scope: kAudioDevicePropertyScopeOutput, element: 2
kAudioDevicePropertyVolumeDecibels ('vold'), scope: kAudioDevicePropertyScopeOutput, element: 2
Unknown ('vmvc'), scope: kAudioDevicePropertyScopeOutput, element: 0
Unknown ('vmbc'), scope: kAudioDevicePropertyScopeOutput, element: 0
The question is about the two unknown notifications with FourCC codes ‘vmvc’ and ‘vmbc’, above. They are not defined anywhere in the Core Audio headers, can anyone tell me what they are and what the “kAudioDeviceProperty…” name is for them?
They seem to be sent every time the volume is changed for a channel along with the scalar and dB ones.
Regards,
Tim.
From AudioServices.h
CF_ENUM(AudioObjectPropertySelector)
{
kAudioHardwareServiceProperty_ServiceRestarted = 'srst',
kAudioHardwareServiceDeviceProperty_VirtualMasterVolume = 'vmvc',
kAudioHardwareServiceDeviceProperty_VirtualMasterBalance = 'vmbc'
};
regards,
edward
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