[LAD] Half-OT: Fader mapping - was - Ardour MIDI tracer

[Clemens Ladisch]

Len Ovens wrote:
> On Thu, 21 Aug 2014, John Rigg wrote:
>> ... faders with a roughly logarithmic taper (no VCAs).
>
> Which log? I would think .5 db for the same amount of movement the
> entire fader length would be logarithmic (log 10).

For a fader from -INF to zero, alsamixer uses dB = 6000 * log10(pos),
where pos is 0...1:
<http://git.alsa-project.org/?p=alsa-utils.git;a=blob;hb=HEAD;f=alsamixer/volume_mapping.c>


Regards,
Clemens