Re: [CM] portamento

[bil]

I think in the context of sound synthesis, portamento
is a glissando between two notes.  It would be interesting
to get a vocal or violin recording of someone using
portamento, and try to imitate it -- I think you'll
also need an amplitude envelope.  Seashore wrote about
it, saying something like "it starts below the first
note and overshoots its target", if I remember right.
You might also need to change the timbre en route.

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[CM] portamento

[James Hearon]

Hi,
I'm trying to come up with an approach to portamento note phrasing.  Best I've 
been able to do is work with gliss.  I'm wondering if this is on the right 
track for how this is usually handled?

Regards,
Jim

(definstrument (myport start-time duration frequency start-freq end-freq 
(amp-env '(0 0 1 1 2 1 3 0)) sampling-rate)
  (let* ((beg (floor (* start-time sampling-rate)))
(end (+ beg (floor (* duration sampling-rate
(sine-wave (make-oscil :frequency frequency))
(ampf (make-env amp-env :duration duration :scaler 1.0))
(frqf (make-env '(0 0 1 1) :scaler (hz->radians (- end-freq start-freq)) 
:duration duration :base 0.67))
 )
 (do ((i beg (+ i 1)))
 ((= i end))
 (outa i (* (env ampf) (oscil sine-wave (env frqf) )))
 (outb i (* (env ampf) (oscil sine-wave (env frqf) )))
 )))

(with-sound (:srate 48000 :channels 2 :header-type mus-riff  :play #t)
  (myport 0 1 300 300 400 '(0 1 1 .3) 48000)
  (myport 2 1.5 400 400 300 '(0 .3 1 .3) 48000)
)
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