/usr/share/audacity/plug-ins/delay.ny is in audacity-data 2.0.5-1ubuntu3.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 | ;nyquist plug-in
;version 3
;type process
;categories "http://lv2plug.in/ns/lv2core#DelayPlugin"
;name "Delay..."
;action "Applying Delay Effect..."
;; by Steve Daulton, July 2012.
;; based on 'Delay' by David R. Sky
;; Released under terms of the GNU General Public License version 2:
;; http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
;;
;; For information about writing and modifying Nyquist plug-ins:
;; http://wiki.audacityteam.org/wiki/Nyquist_Plug-ins_Reference
;control delay-type "Delay type" choice "regular,bouncing ball,reverse bouncing ball" 0
;control dgain "Delay level per echo (dB)" real "" -6 -30 1
;control delay "Delay time (seconds)" real "" 0.3 0 5
;control pitch-type "Pitch change effect" choice "Pitch/Tempo,LQ Pitch Shift" 0
;control shift "Pitch change per echo (semitones)" real "" 0 -2 2
;control number "Number of echoes" int "" 5 1 30
;control constrain "Allow duration to change" choice "Yes,No" 0
;; The default pitch shift effect is a simple resampling,
;; so both pitch and tempo of the delayed audio will change
;; [as in Audacity's Change Speed effect].
;; LQ Pitch Shift (Low Quality) changes the pitch without
;; changing the tempo, but the sound quality is not very good
;; and tends to cause a short echo effect which can be quite
;; noticeable on percussive sounds though may be acceptable
;; on other sounds.
(setf err "") ; initialise error message
(defun err-chk (arg min max)
(if (or (< arg min) (> arg max))
T nil))
(when (err-chk number 1 50)(setq err (format nil
"Number of echoes '~a' outside valid range 1 to 50.~%~a"
number err)))
(when (err-chk shift -12 12)(setq err (format nil
"Pitch change '~a' outside valid range -12 to +12 semitones.~%~a"
shift err)))
(when (err-chk delay 0 10)(setq err (format nil
"Delay time '~a' outside valid range 0 to 10 seconds.~%~a"
delay err)))
(when (err-chk dgain -30 6)(setq err (format nil
"Delay level '~a' outside valid range -30 to +6 dB.~%~a"
dgain err)))
;;; anti-alias low pass filter
(defun lp-wall (sig freq)
(do ((count 0 (1+ count))
(freq (* 0.94 freq)))
((= count 10) sig)
(setf sig (lowpass8 sig freq))))
;;; Change speed
(defun change-speed (sig shift)
(if (= shift 0) ; no pitch shift
sig
(let ((ratio (expt 0.5 (/ shift 12.0)))) ; shift value as frequency ratio
(force-srate *sound-srate*
(stretch-abs ratio (sound sig))))))
;;; pitch shift audio
(defun p-shift (sig shift)
(if (= shift 0) ; no pitch shift
sig
(let ((sig (force-srate 44100 sig)) ; pitshift quality best at 44100
; anti-alias filter frequency
(minrate (* 0.5 (min *sound-srate* 44100)))
(ratio (expt 0.5 (/ shift -12.0)))) ; shift value as frequency ratio
(force-srate *sound-srate* ; convert back to correct rate
(progv '(*sound-srate*) (list 44100) ; pitshift requires rates to match
(cond
((> shift 5) ; reduce aliasing
(pitshift (lp-wall sig (/ minrate ratio)) ratio 1))
((< shift -2)
(pitshift (hp sig 20) ratio 1)) ; reduce sub-sonic frequencies
(T (pitshift sig ratio 1))))))))
;;; apply effects to echo
(defun modify (sig num gain shift p-type)
(let ((gain (db-to-linear (* num gain)))
(shift (* num shift)))
(if (= p-type 0)
(mult gain (change-speed sig shift))
(mult gain (p-shift sig shift)))))
;;; compute echoes
(defun delays (sound gain delay shift num type mod)
(let ((echo (s-rest 0)))
(do ((count 1 (1+ count))
(dly 0))
((> count num)(sim echo sound))
(setq dly
(case type
(0 (+ dly delay))
(1 (+ dly (* delay (- (1+ num) count))))
(2 (+ dly (* delay count)))))
(setf echo (sim
(at 0 (cue echo))
(at-abs dly
(cue (modify sound count gain shift mod))))))))
(defun constrain-abs (sig dur)
(extract-abs 0 dur (cue sig)))
;;; return errors or process
(if (> (length err) 0)
(format nil "Error.~%~a" err) ; return error
(let* ((delay (if (= delay-type 0) delay (/ delay number)))
(output
(multichan-expand #'delays
s dgain delay shift number delay-type pitch-type)))
(if (= constrain 1)
(multichan-expand #'constrain-abs output (get-duration 1))
output)))
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