[wdmaudiodev] Re: Positive/negative dB range in volume control

  • From: "Mike Kemp" <mjk@xxxxxxxxxxxx>
  • To: <wdmaudiodev@xxxxxxxxxxxxx>
  • Date: Fri, 8 Jul 2011 15:58:45 +0100

Every real volume control you have used stretches the top part of its range across the bulk of the physical travel. It's called the audio taper, and it's what makes it usable. So a range from +12dB to -90 will have say +12 to -12 occupying 3/4 of the physical range. You rarely want precision control below -20dB, whereas above that the ear is sensitive to less than a dB of change and its where you want fine control.


Your range of 180dB is not really a usable range, unless you are listening to butterfly sounds at Cape Canaveral and want to capture the full effect of the last shuttle launch.

You can probably search the documentation for "audio taper" if you want to see if you can alter it, but it sounds like you are doing the wrong thing so if you succeed you will probably have an unusable control.

M.


----- Original Message ----- From: Eugene Muzychenko
To: wdmaudiodev@xxxxxxxxxxxxx
Sent: Friday, July 08, 2011 3:38 PM
Subject: [wdmaudiodev] Positive/negative dB range in volume control


Hello!

Found a strange behavior of Windows volume level regulators. If a
driver returns a volume level range that crosses the zero
(-n..+n dB), Windows volume control applets (XP and Win7) make a
very uneven scale for the sliders. For example, if the range returned
is -90..+90 dB, the "0 dB" position is about 5% from the bottom
(almost a lower position). If the range is -90..+60 dB, the zero
position is a little higher (about 7%). Only with a very narrow positive
range (-90..+12 dB), the zero position is near to the center.

It looks like a "logarithm of a logarithm", i.e. a slider scale is
double-logarithmic, while it should be linear for the dB levels.

Why volume control application do such strange scaling? Maybe there is
a way to make a linear slider scale?

Regards,
Eugene


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