To pile onto Frank's comment, the taper algorithm for XP RTM, XP SP2 and Win7
are all different (I don't remember if Vista and Win7 have different tapers).
The IAudioEndpointVolume::SetMasterVolumeLeveldB API is guaranteed to *not*
apply a taper; it's the only API (other than directly setting
KSPROPERTY_AUDIO_VOLUMELEVEL directly) which is guaranteed not to apply a
taper. And of course that assumes that the audio driver isn't applying its own
taper (unfortunately we've found external drivers which do that).
Larry
-----Original Message-----
From: wdmaudiodev-bounce@xxxxxxxxxxxxx
[mailto:wdmaudiodev-bounce@xxxxxxxxxxxxx] On Behalf Of Frank Yerrace
Sent: Friday, April 22, 2011 3:54 PM
To: wdmaudiodev@xxxxxxxxxxxxx
Subject: [wdmaudiodev] Re: Setting KSPROPERTY_AUDIO_VOLUMELEVEL
Since the "feel" of a taper is a somewhat subjective thing, and there's
possibility of tweaks/adjustments/improvements in this in different releases of Windows,
the taper function is not documented. Otherwise apps might start taking dependencies on
it and eventually cause compatibility challenges.
Frank Yerrace
Microsoft Corporation
