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https://github.com/cookiengineer/audacity
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42 lines
1.3 KiB
Common Lisp
42 lines
1.3 KiB
Common Lisp
;nyquist plug-in
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;version 1
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;type process
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;categories "http://lv2plug.in/ns/lv2core#MixerPlugin"
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;name "Studio Fade Out"
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;action "Applying Fade..."
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;; StudioFadeOut.ny by Steve Daulton December 2012.
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;; Released under terms of the GNU General Public License version 2:
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;; http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
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;;
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;; Produce a smooth and musical sounding fade out.
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;; Applies a sinusoidal fade out with a progressive low-pass
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;; filter from full spectrum at start to 100 Hz at end.
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;;
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;; For information about writing and modifying Nyquist plug-ins:
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;; http://wiki.audacityteam.org/wiki/Nyquist_Plug-ins_Reference
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;;; sweeping low pass filter
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(defun filter (sig dur)
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(abs-env
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;; cross-fade the filter
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(let* ((nyq-hz (/ *sound-srate* 2))
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(f-out (r-cos (min (/ dur 2.0) 0.5)))
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(f-in (diff (snd-const 1 0 *sound-srate* dur) f-out)))
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(sim
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(mult f-out sig)
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(mult f-in (lp sig (pwlv nyq-hz dur 100)))))))
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;;; raised cosine
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(defun r-cos (dur)
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(abs-env
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(mult 0.5
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(sum 1
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(osc (hz-to-step (/ (* dur 2))) dur *table* 90)))))
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(let ((dur (get-duration 1)))
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(cond
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((< len 3) "Selection too short.\nIt must be more than 2 samples.")
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((< dur 0.2) (mult s (r-cos dur)))
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(t (mult (filter s dur)(r-cos dur)))))
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