Locate and position the current Audacity source code, and clear a variety of old junk out of the way into junk-branches

plug-ins/delay.ny

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+;nyquist plug-in
+;version 3
+;type process
+;categories "http://lv2plug.in/ns/lv2core#DelayPlugin"
+;name "Delay..."
+;action "Performing Delay Effect..."
+;info "by Roger Dannenberg, modified by David R. Sky\nReleased under terms of the GNU General Public License Version 2 \nDelay type: 'bouncing ball' makes the echoes occur increasingly close\ntogether (faster); 'reverse bouncing ball' makes them occur increasingly far\napart (slower). In either bouncing ball effect, delay time is not time between\nechoes but the * maximum * delay time in bounces.\nApplying delay can cause clipping (distortion), especially when reducing the\ndecay value and using more echoes. It's normally best to use Effect > Amplify\nto set the peak amplitude to -6 dB before using delay.     
+
+;control delay-type "Delay type" choice "regular,bouncing ball,reverse bouncing ball" 0
+;control decay "Decay amount [dB; negative value increases volume]" real "" 6 -1 24
+;control delay "Delay time [seconds]" real "" 0.5 0 5
+;control shift "Pitch change per echo [semitones; negative value = lower, 0 is off]" real "" 0 -2 2
+;control count "Number of echoes" int "" 5 1 30
+
+; Delay by Roger B. Dannenberg
+; modified by David R. Sky October 2007, 
+; adding negative decay values, which gives delay effect
+; increasing volume with each delay; and adding
+; bouncing ball and reverse bouncing ball delay effects
+; and pitch [semitone] change with each echo.
+; modified by Richard Ash January 2008, removing all 
+; normalization functions. 
+
+; Note by Roger Dannenberg: this effect will use up memory proportional to
+; delay * count, since that many samples must be buffered
+; before the first block is freed.
+
+; initialize empty error message
+(setf error-msg "")
+
+
+; check function: returns 1 on error
+(defun check (arg min max)
+(if (and (>= arg min) (<= arg max))
+0 1))
+
+
+; checking for erroneous user-input values:
+(setf error-msg (if (= (check decay -1 24) 0)
+error-msg 
+(strcat error-msg 
+(format nil "Decay value '~a' outside valid range -1.0 to 24.0 dB. 
+" decay))))
+
+(setf error-msg (if (= (check delay 0 5) 0)
+error-msg 
+(strcat error-msg 
+(format nil "Delay value '~a' outside valid range 0.0 to 5.0 seconds. 
+" delay))))
+
+(setf error-msg (if (= (check shift -2 2) 0)
+error-msg 
+(strcat error-msg 
+(format nil "Pitch change value '~a' outside valid range -2.0 to 2.0 semitones. 
+" shift))))
+
+(setf error-msg (if (= (check count 1 30) 0)
+error-msg 
+(strcat error-msg 
+(format nil "Number of echoes '~a' outside valid range 1 to 30 echoes. 
+" count))))
+; finished error-checking
+
+; if error-msg is longer than 0 characters,
+; prepend opening message
+(setf error-msg (if (> (length error-msg) 0)
+(strcat "Error -\n\nYou have input at least one invalid value:
+" error-msg)
+error-msg))
+
+(cond ; 1
+((> (length error-msg) 0)
+(format nil "~a" error-msg))
+
+(t ; no input errors, perform delay
+
+; convert shift value to a value the Nyquist code understands
+(setf shift (expt 0.5 (/ shift 12.0)))
+
+; for bouncing ball effects, set delay time to delay time/count
+(setf delay (if (> delay-type 0)
+(/ delay count) delay))
+
+
+
+; function to stretch audio 
+(defun change (sound shift)
+(if (arrayp sound)
+(vector
+(force-srate 44100 (stretch-abs shift (sound (aref sound 0))))
+(force-srate 44100 (stretch-abs shift (sound (aref sound 1)))))
+(force-srate 44100 (stretch-abs shift (sound sound)))))
+
+
+(cond ; 2
+((= delay-type 0) ; regular delay
+; delay function
+(defun delays (s decay delay count shift)
+  (if (= count 0) (cue s)
+	 (sim (cue s)
+			(loud decay (at delay (delays (change s shift) 
+decay delay (- count 1) shift))))))
+
+(stretch-abs 1 (delays s (- 0 decay) delay count shift)))
+
+
+((= delay-type 1) ; bouncing ball delay
+; bouncing ball delay function
+(defun bounces (s decay delay count shift)
+  (if (= count 0) (cue s)
+      (sim (cue s)
+               (loud decay (at (mult delay count) 
+(bounces (change s shift) decay delay 
+(- count 1) shift)))))) 
+
+(stretch-abs 1 (bounces s (- 0 decay) delay count shift)))
+
+
+((= delay-type 2) ; reverse bouncing ball delay
+; reverse bouncing ball delay function
+(defun revbounces (s decay delay count revcount shift)
+  (if (= count 0) (cue s)
+      (sim (cue s)
+               (loud decay (at (mult delay (- revcount count))
+(revbounces (change s shift) decay delay 
+(- count 1 ) revcount shift)))))) 
+
+(setf revcount (1+ count))
+(stretch-abs 1 (revbounces s (- 0 decay) delay count revcount shift)))
+) ; end cond2, different delay effect choices
+) ; end cond1 t
+) ; end cond 1