Bug 1275 - No preview in Spectral edit effects

Introduces a new type 'spectral' t Nyquist plug-ins

plug-ins/SpectralEditShelves.ny

@@ -1,6 +1,6 @@
 ;nyquist plug-in
 ;version 4
-;type process
+;type process spectral
 ;preview linear
 ;name "Spectral edit shelves..."
 ;action "Filtering..."
@@ -9,35 +9,31 @@
 
 
 ;; SpectralEditShelves.ny by Paul Licameli, November 2014.
-;; Updated to version 4 by Steve Daulton November 2014.
+;; Updated by Steve Daulton 2014 / 2015.
 ;; Released under terms of the GNU General Public License version 2:
 ;; http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
 
 ;control control-gain "Gain (dB)" real "" 0 -24 24
 
-(setf control-gain (min 24 (max -24 control-gain))) ; excessive settings may crash
-
 (defmacro validate (hz)
-"Ensure frequency is below Nyquist"
-  `(setf ,hz (max 0 (min (/ *sound-srate* 2.0) ,hz))))
+"If frequency is above Nyquist, don't use it"
+  `(if (or (>= ,hz (/ *sound-srate* 2.0))
+           (<= ,hz 0))
+        (setf ,hz nil)))
 
 (defun mid-shelf (sig lf hf gain)
   "Combines high shelf and low shelf filters"
-  (let* ((invg (- gain)))
+  (let ((invg (- gain)))
     (scale (db-to-linear gain)
            (eq-highshelf (eq-lowshelf sig lf invg)
                          hf invg))))
 
 (defun wet (sig gain f0 f1)
+  "Apply appropriate filter"
   (cond
-   ((not f0) (eq-lowshelf sig (validate f1) gain))
-   ((not f1) (eq-highshelf sig (validate f0) gain))
-   (t
-    (validate f0)
-    (validate f1)
-    (when (= f0 f1)
-      (throw 'error-message "Please select a frequency range."))
-    (mid-shelf sig f0 f1 gain))))
+    ((not f0) (eq-lowshelf sig f1 gain))
+    ((not f1) (eq-highshelf sig f0 gain))
+    (t (mid-shelf sig f0 f1 gain))))
 
 (defun result (sig)
   (let*
@@ -51,24 +47,26 @@
        (breakpoints (list t1 1.0 t2 1.0 tn))
        (env (snd-pwl 0.0 rate breakpoints)))
     (cond
-      ((not (or f0 f1))
+      ((not (or f0 f1)) ; This should never happen for a 'spectral' effect.
           (throw 'error-message (format nil "~aPlease select frequencies." p-err)))
-      ; shelf is above Nyquist frequency so do nothing
-      ((and f0 (>= f0 (/ *sound-srate* 2.0))) nil)
-      (T (sum (prod env (wet sig control-gain f0 f1))
-              (prod (diff 1.0 env) sig))))))
-
-;; Frequency selection must be between 0 Hz and Nyquist.
-(if (and (get '*selection* 'low-hz)
-         (<= (get '*selection* 'low-hz) 0))
-    (remprop '*selection* 'low-hz))
-(if (and (get '*selection* 'high-hz)
-         (>= (get '*selection* 'high-hz)(/ *sound-srate* 2)))
-    (remprop '*selection* 'high-hz))
+      ((and f0 (>= f0 (/ *sound-srate* 2.0)))
+          ; Shelf is above Nyquist frequency so do nothing.
+          nil)
+      ((and f0 f1 (= f0 f1))
+          (throw 'error-message
+            (format nil "~aBandwidth is zero (the upper and lower~%~
+                         frequencies are both ~a Hz).~%~
+                         Please select a frequency range."
+                    p-err f0)))
+      (T  (if f0 (validate f0))
+          (if f1 (validate f1))
+          (if (not (or f0 f1))  ; 'validate' may return nil
+              nil               ; Do nothing
+              (sum (prod env (wet sig control-gain f0 f1))
+                  (prod (diff 1.0 env) sig)))))))
 
 (catch 'error-message
-  (setf p-err "")
-  (if (= control-gain 0)		; Allow dry preview
-      "Gain is zero. Nothing to do."
-    (multichan-expand #'result *track*)))
-
+  (setf p-err "Error.\n")
+  (if (= control-gain 0)
+      nil ; Do nothing
+      (multichan-expand #'result *track*)))