[LAD] panning thoughts
Folderol
folderol at ukfsn.org
Sat Nov 13 09:07:35 UTC 2010
On Fri, 12 Nov 2010 23:45:56 +0100
Arnold Krille <arnold at arnoldarts.de> wrote:
> On Friday 12 November 2010 17:47:08 gene heskett wrote:
> > On Friday, November 12, 2010 11:43:42 am Eric Kampman did opine:
> > > On Nov 12, 2010, at 1:40 AM, Jens M Andreasen wrote:
> > > > On Thu, 2010-11-11 at 20:22 -0800, Eric Kampman wrote:
> > > >> Since power is proportional to signal squared, this means ..
> > > >> .. L(t) = cos(t * pi / 2) and R(t) = cos((1 - t) * pi / 2)
> > > >
> > > > I think you misspelled one sin(), no?
> > >
> > > No, turns out the 2nd equation is equivalent to sin(t * pi / 2) I think.
> >
> > And is computationally less expensive if you drop the pi / 2 and use
> > pi * 0.5 as mulls cost less than divs. Or at least this is true if its not
> > handed off to an FP processor. ;-)
>
> Even faster: Use a pre-computed value of pi/2 or pi*0.5. I don't think
> compilers will already optimize such a constant part of an equation.
>
> Arnold
Why not go the whole hog and use a pre-calculated look-up table for the whole
thing?
You will only want a limited number of points, and then only from centre to one
side - the other is of course mirror image.
--
Will J Godfrey
http://www.musically.me.uk
Say you have a poem and I have a tune.
Exchange them and we can both have a poem, a tune, and a song.
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