repeat a chirp/silence sequence with decreasing time length

Programming and Development Nyquist
1

Hi all
My first post here. Hope it is the right place to post.

I use audacity 2.2.2 on opensuse 15.1 workstation. Audacity is from stock opensuse repos.

My aim is to generate a sequence of chirps say from 50 to 1kHz followed by silence, both of the same duration. It should be followed by the same chirp/silence sequence, but the duration should be decreased by say 0.025 seconds. I would the sequence to be repeated until the duration is about 0.2 seconds. Manually It would require about 400 generate cycles. I was hoping this could be solved by scripting and/or macros.
I do C++ and bash programming regularly. So I am looking for some initial support to get me going.

Hope someone can jump in
Greez chris

2

This can be scripted using Audacity’s built-in scripting language “Nyquist” (https://manual.audacityteam.org/man/nyquist.html)

This code work in the “Nyquist Prompt” (https://manual.audacityteam.org/man/nyquist_prompt.html):

;version 4
;type generate

(setf dur 1.0) ;initial chirp duration
(setf min-dur 0.2)
(setf decrease-dur-by 0.025)
(setf initial-hz 50)
(setf final-hz 1000)
(setf initial-amp 0.8)
(setf final-amp 0.1)

(defun chirp (hz0 hz1 g0 g1 dur)
  (mult (hzosc (pwlv hz0 dur hz1))
        (pwlv g0 dur g1)))

(defun make-chirp (dur)
  (seq (chirp initial-hz
              final-hz
              initial-amp
              final-amp
              dur)
       (s-rest dur)))

(let ((output (s-rest 0)))
  (do* ((d dur (- d decrease-dur-by))
        (time 0 (+ time (* 2 d))))
       ((< d min-dur) output)
    (setf output
        (sim output
             (at time (cue (make-chirp d)))))))

In Nyquist, functions are called in the form: (function-name list-of-arguments).
To see how the code works, look up each of the function names in the Nyquist manual index: https://www.cs.cmu.edu/~rbd/doc/nyquist/indx.html

3

Steve
Just a short THANK YOU: Great!!! Got to learn nyquist!
Greez
chris

4

I’ve moved this topic to the Nyquist forum.
If you have further questions about Nyquist, this is the forum board to post your questions.

5

Steve
Perfect, thank you. adjusted your script and now I have exactly what I wanted. So big thx! I will start learning nyqist this weekend. I feel it is very powerful. I showed it to a colleague of mine. He is a music producer and has lots of weird ideas :slight_smile:.

Greez
chris

6

You’re welcome, and congratulations on modifying it to suit your needs.

It is :smiley:


Nyquist is fantastic for trying out weird ideas - I do that all the time :laughing: