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 -----Original Message----- From: wdmaudiodev-bounce@xxxxxxxxxxxxx [mailto:wdmaudiodev-bounce@xxxxxxxxxxxxx] On Behalf Of Robert Bielik Sent: Friday, April 22, 2011 3:53 AM To: wdmaudiodev@xxxxxxxxxxxxx Subject: [wdmaudiodev] Re: Setting KSPROPERTY_AUDIO_VOLUMELEVEL Frank Yerrace skrev 2011-04-21 20:45: > Note that certain so-called "scalar" volume APIs already have a taper built > into them. Unfortunately this isn't always clear in the docs or from the > function names. Specifically, > IAudioEndpointVolume::SetMasterVolumeLevelScalar has a taper, allowing a UI > developer to simply map the 0..1 range directly to physical travel in his UI. Interesting. Would it be to much to ask for the taper parameters ? Note that I cannot rely on IAudioEndpointVolume as my implementation must work from XP onwards. Regards, /Rob ****************** WDMAUDIODEV addresses: Post message: mailto:wdmaudiodev@xxxxxxxxxxxxx Subscribe: mailto:wdmaudiodev-request@xxxxxxxxxxxxx?subject=subscribe Unsubscribe: mailto:wdmaudiodev-request@xxxxxxxxxxxxx?subject=unsubscribe Moderator: mailto:wdmaudiodev-moderators@xxxxxxxxxxxxx URL to WDMAUDIODEV page: http://www.wdmaudiodev.com/ ****************** WDMAUDIODEV addresses: Post message: mailto:wdmaudiodev@xxxxxxxxxxxxx Subscribe: mailto:wdmaudiodev-request@xxxxxxxxxxxxx?subject=subscribe Unsubscribe: mailto:wdmaudiodev-request@xxxxxxxxxxxxx?subject=unsubscribe Moderator: mailto:wdmaudiodev-moderators@xxxxxxxxxxxxx URL to WDMAUDIODEV page: http://www.wdmaudiodev.com/ ****************** WDMAUDIODEV addresses: Post message: mailto:wdmaudiodev@xxxxxxxxxxxxx Subscribe: mailto:wdmaudiodev-request@xxxxxxxxxxxxx?subject=subscribe Unsubscribe: mailto:wdmaudiodev-request@xxxxxxxxxxxxx?subject=unsubscribe Moderator: mailto:wdmaudiodev-moderators@xxxxxxxxxxxxx URL to WDMAUDIODEV page: http://www.wdmaudiodev.com/