[wdmaudiodev] Re: Setting KSPROPERTY_AUDIO_VOLUMELEVEL
- From: Frank Yerrace <Frank.Yerrace@xxxxxxxxxxxxx>
- To: "wdmaudiodev@xxxxxxxxxxxxx" <wdmaudiodev@xxxxxxxxxxxxx>
- Date: Wed, 20 Apr 2011 17:04:54 +0000
To emphasize Matt's point, please implement your driver's volume controls
correctly. The definition of the property values for
KSPROPERTY_AUDIO_VOLUMELEVEL is clearly defined in
http://msdn.microsoft.com/en-us/library/ff537309(VS.85).aspx. Please don't
deviate from that.
I don't know much about your product, but a volume control that with a range of
-91dB to +3dB isn't real useful in most *typical* PC environments, and could
give the perception that much of the physical "travel" of the control has no
affect. Is there a reason you want your volume control to have such a large
range.
Frank Yerrace
Microsoft Corporation
-----Original Message-----
From: wdmaudiodev-bounce@xxxxxxxxxxxxx
[mailto:wdmaudiodev-bounce@xxxxxxxxxxxxx] On Behalf Of Matthew van Eerde
Sent: Wednesday, April 20, 2011 9:40 AM
To: wdmaudiodev@xxxxxxxxxxxxx
Subject: [wdmaudiodev] Re: Setting KSPROPERTY_AUDIO_VOLUMELEVEL
The assumption baked in to the design is that the dB stepping values exposed by
the driver are accurate; if that's not the case all of the complicated volume
processing that goes on above the driver is a game of blind-man's-buff.
Specifically, if you go from step #X to step #(X+3) and the steps are 1.5 dB
apart, there should be a perceived volume change of 4.5 dB. This should hold
true whether X is the bottom step, or the third step from the top, or any step
in the middle.
It sounds like this is not the case on any of the three devices you tried.
Can you run dxdiag on the three systems in question, "Save All Information",
and send the resulting dxdiag.txt files to me directly (off-list?)
matthew.van.eerde@xxxxxxxxxxxxx
-----Original Message-----
From: wdmaudiodev-bounce@xxxxxxxxxxxxx
[mailto:wdmaudiodev-bounce@xxxxxxxxxxxxx] On Behalf Of Robert Bielik
Sent: Wednesday, April 20, 2011 9:18 AM
To: wdmaudiodev@xxxxxxxxxxxxx
Subject: [wdmaudiodev] Re: Setting KSPROPERTY_AUDIO_VOLUMELEVEL
Matthew van Eerde skrev 2011-04-20 18:03:
>
> There are several ways to interpret a "v" in [0, 1] scale, with very
> different effects:
>
I agree, but for me the only "sensible" interpretation is that I map v [0,1]
linearly to [SignedMinimum, SignedMaximum] , i.e.
0.5 maps to (SignedMaximum + SignedMinimum)/2. But the perceived result is
anything but "linear-in-dB". This is what I'm confused about.
Maybe its a driver thing, but 3 different devices show the same behavior.
Anyway, I did a mapping of v [0,1] to v_s [0,1] where v_s = exp(log(v)/3.0) and
v = pow(v_s, 3.0) and that seems to work quite satisfactorily, so I'll go with
that for now.
Regards,
/Rob
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