linuxaudio.org

Excerpts from Ralf Mardorf's message of 2010-11-13 14:17:46 +0100:

quoted text
> On Sat, 2010-11-13 at 11:54 +0100, fons@kokkinizita.net wrote:

> > On Sat, Nov 13, 2010 at 09:07:35AM +0000, Folderol wrote:

> >

> > > Why not go the whole hog and use a pre-calculated look-up table for the whole

> > > thing?

> >

> > You only need to compute the L,R gains when they change.

> > Using a second order approximation such as the ones I

> > poster earlier is probably faster than a lookup table

> > in practice.

> >

> > Here's one more:

> >

> > p = panning position, 0...1

> > m = panning law control, 0...1

> >

> > q = 1 - p

> > d = m * p * q

> > L_gain = q + d

> > R_gain = p + d

> >

> > m = 0 -> -6 dB at center

> > m = 1 -> -2.5 dB at center

> >

> > This takes three additions and two multiplications, which is peanuts.

> >

> > Ciao,

>

> Thank you for your explanations Fons :).

>

> Is there a 'most common value' for the centre?

>

> I do know several analog mixing consoles from el cheapo to very

> expensive and all pan pots are ok, I can't notice an audible difference.

> I only know one very el cheapo mixing console, the Yamaha RM 602,

> http://i1.tinypic.com/6fzx1k1.jpg , where the pan pots are crappy. As a

> youngster I started with this mixer :), using the pan pot means to

> readjust the faders ;).

>

> Cheers!

>

> Ralf

One thing I wonder about is the exact value of the center. I've seen

panning in software between -1 and +1 and a center of +/- 0 where it

made a difference whether it was + or -. It's easy to get confused by

stuff like that if you're a nitpicker :)
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