[PlanetCCRMA] Re: sine waves in real time

[Fernando Lopez-Lezcano]

On Mon, 2007-10-15 at 15:22 -0700, Bill Schottstaedt wrote:
> > On a very recent Intel laptop running a Core Duo at 2.4GHz (I think
> > that's the speed), SuperCollider would do 500 interpolated sine
> > oscillators with a (roughly) 50% cpu load (in one of the cores).
> 
> In the Scheme version of Snd, at 44100 KHz, I get about 180 such
> sines (actually, I'm calling the sin function, not interpolating some
> table):
> 
> (with-sound (:statistics #t) 
>   (let ((gens (make-vector 180))) 
>     (do ((i 0 (1+ i)))
>         ((= i 180))
>       (vector-set! gens i (make-oscil (* 10 (1+ i)) (random (* 2 pi)))))
>     (run
>      (lambda ()
>        (do ((i 0 (1+ i)))
>            ((= i 44100))
>          (let ((sum 0.0))
>            (do ((k 0 (1+ k)))
>                ((= k 180))
>              (set! sum (+ sum (oscil (vector-ref gens k)))))
>            (outa i (* .01 sum) *output*)))))))
> 
> ;test.snd:
>   maxamp: 0.2935
>   compute time: 1.020

Wow, that's impressive. 180 directly from scheme...
I never tried Kjetil's realtime snd, that would (presumable) be faster?

-- Fernando


> 30% of the time is handling the loops and writing output, nearly all the rest
> is in the oscils, so if I were writing direct to a DAC, I'd estimate 200.
> More interesting to me is the same question with the fm-violin -- I
> think I get 53:
> 
> (with-sound (:statistics #t)
>   (do ((k 0 (1+ k)))
>       ((= k 53))
>     (fm-violin 0 1 440 .01)))
> 
> ;test.snd:
>   maxamp: 0.4320
>   compute time: 1.000
> 
> 
> In the Common Lisp (sbcl) clm, I get around 68:
> 
> (with-sound (:srate 44100 :statistics t) (do ((i 0 (1+ i))) ((= i 68)) (fm-violin 0 1 440 .01)))
> test.snd: 
>   Duration: 1.0000, Last begin time: 0.0000
>   Compute time: 0.997, Compute ratio: 1.00
>   OutA max amp: 0.559 (near 0.249 secs)
> "test.snd"
> 
> 
> and presumably the sine wave case would scale similarly.