[LAD] Presenting volume control sliders
cannam at all-day-breakfast.com
Thu May 21 19:48:33 UTC 2009
On Thu, May 21, 2009 at 8:27 PM, Lennart Poettering <mzynq at 0pointer.de> wrote:
> From reading through the ALSA drivers I know that a lot of sound card
> mixer controls usually have a much higher dB resolution near 0dB then
> the have near -90dB. Most of the time the steps they choose are very
> arbitrary however.
There is an IEC standard for this mapping in meters (IEC 60-268-18)
which works OK for faders as well if extended in a sensible way down
to -inf, particularly if you don't want to go above 0dB. It divides
the range up into several sections which are individually linear in
dB. There's code for this mapping in several places, including
base/AudioLevel.cpp in the Rosegarden source code.
A cubic mapping is also good.
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