[wdmaudiodev] Re: USB Audio specification - feature unit question
- From: Matthew van Eerde <Matthew.van.Eerde@xxxxxxxxxxxxx>
- To: "wdmaudiodev@xxxxxxxxxxxxx" <wdmaudiodev@xxxxxxxxxxxxx>
- Date: Mon, 10 Sep 2012 15:47:35 +0000
Windows will inject a software mute control if the driver does not provide a
hardware mute control.
If you look at the filter nodes in KS Studio you can tell whether the driver
is exposing a hardware mute, or you can call
IAudioEndpointVolume::QueryHardwareSupport from an app.
From: wdmaudiodev-bounce@xxxxxxxxxxxxx
[mailto:wdmaudiodev-bounce@xxxxxxxxxxxxx] On Behalf Of Bartosik Lukasz-ALB045
Sent: Monday, September 10, 2012 6:01 AM
To: wdmaudiodev@xxxxxxxxxxxxx
Subject: [wdmaudiodev] USB Audio specification - feature unit question
Hello,
I've got a question related to behavior of feature unit in Windows 7.
I have a feature unit which supports only volume control for master channel:
===>Audio Control Feature Unit Descriptor<===
bLength: 0x09
bDescriptorType: 0x24
bDescriptorSubtype: 0x06
bUnitID: 0x06
bSourceID: 0x05
bControlSize: 0x01
bmaControls[0]:
02
bmaControls[1]:
00
iFeature: 0x00
And when I go to "Levels" tab in properties for that audio device the volume
slider is there,
however there is also mute control enabled even though configuration of feature
unit advertised support for volume only.
Any clues why mute control is not disabled ?
Thanks,
Lukasz
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