79 lines
2.7 KiB
Common Lisp
79 lines
2.7 KiB
Common Lisp
$nyquist plug-in
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$version 4
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$type process spectral
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$preview linear
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$name (_ "Spectral edit shelves")
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$manpage "Spectral_edit_shelves"
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$action (_ "Filtering...")
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$author (_ "Paul Licameli")
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$release 2.3.0
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$copyright (_ "Released under terms of the GNU General Public License version 2")
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;; SpectralEditShelves.ny by Paul Licameli, November 2014.
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;; Updated by Steve Daulton 2014 / 2015.
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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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;; For information about writing and modifying Nyquist plug-ins:
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;; https://wiki.audacityteam.org/wiki/Nyquist_Plug-ins_Reference
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$control control-gain (_ "Gain (dB)") real "" 0 -24 24
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(defmacro validate (hz)
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"If frequency is above Nyquist, don't use it"
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`(if (or (>= ,hz (/ *sound-srate* 2.0))
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(<= ,hz 0))
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(setf ,hz nil)))
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(defun mid-shelf (sig lf hf gain)
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"Combines high shelf and low shelf filters"
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(let ((invg (- gain)))
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(scale (db-to-linear gain)
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(eq-highshelf (eq-lowshelf sig lf invg)
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hf invg))))
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(defun wet (sig gain f0 f1)
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"Apply appropriate filter"
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(cond
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((not f0) (eq-lowshelf sig f1 gain))
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((not f1) (eq-highshelf sig f0 gain))
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(t (mid-shelf sig f0 f1 gain))))
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(defun result (sig)
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(let*
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((f0 (get '*selection* 'low-hz))
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(f1 (get '*selection* 'high-hz))
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(tn (truncate len))
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(rate (snd-srate sig))
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(transition (truncate (* 0.01 rate))) ; 10 ms
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(t1 (min transition (/ tn 2))) ; fade in length (samples)
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(t2 (max (- tn transition) (/ tn 2))) ; length before fade out (samples)
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(breakpoints (list t1 1.0 t2 1.0 tn))
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(env (snd-pwl 0.0 rate breakpoints)))
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(cond
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((not (or f0 f1)) ; This should never happen for a 'spectral' effect.
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(throw 'error-message (format nil (_ "~aPlease select frequencies.") p-err)))
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((and f0 (>= f0 (/ *sound-srate* 2.0)))
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; Shelf is above Nyquist frequency so do nothing.
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nil)
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((and f0 f1 (= f0 f1))
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(throw 'error-message
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(format nil (_ "~aBandwidth is zero (the upper and lower~%~
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frequencies are both ~a Hz).~%~
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Please select a frequency range.")
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p-err f0)))
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(T (if f0 (validate f0))
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(if f1 (validate f1))
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(if (not (or f0 f1)) ; 'validate' may return nil
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nil ; Do nothing
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(sum (prod env (wet sig control-gain f0 f1))
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(prod (diff 1.0 env) sig)))))))
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(catch 'error-message
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(setf p-err (format nil (_ "Error.~%")))
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(if (= control-gain 0)
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nil ; Do nothing
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(multichan-expand #'result *track*)))
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