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;nyquist plug-in
;version 1
;type analyze
;categories "http://lv2plug.in/ns/lv2core#AnalyserPlugin"
;name "Sound Finder..."
;action "Finding sound..."
;info "Adds region labels for areas of sound according to the specified level\nand duration of surrounding silence. If too many labels are produced,\nincrease the silence level and duration; if too few are produced,\nreduce the level and duration."
;author "Jeremy R. Brown"
;copyright "Released under terms of the GNU General Public License version 2"
;; by Jeremy R. Brown (http://www.jeremy-brown.com/)
;; based on the Silence Finder script by Alex S. Brown (http://www.alexsbrown.com)
;; Released under terms of the GNU General Public License version 2:
;; http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
;control sil-lev "Treat audio below this level as silence [ -dB]" real "" 26 0 100
;control sil-dur "Minimum duration of silence between sounds [seconds]" real "" 1.0 0.1 5.0
;control labelbeforedur "Label starting point [seconds before sound starts]" real "" 0.1 0.0 1.0
;control labelafterdur "Label ending point [seconds after sound ends]" real "" 0.1 0.0 1.0
;control finallabel "Add a label at the end of the track? [No=0, Yes=1]" int "" 0 0 1
;30Dec09: couple of changes made to default control values by Gale Andrews
;Create a function to make the sum the two channels if they are stereo
(defun mono-s (s-in) (if (arrayp s-in) (snd-add (aref s-in 0) (aref s-in 1))
s-in))
;Create a function to reduce the sample rate and prepare the signal for
;analysis. RMS is good to monitor volume the way humans hear it, but is not
;available in Audacity. Used a peak-calculating function instead.
;NOTE: this is the place to add any processing to improve the quality of the
;signal. Noise filters could improve the quality of matches for noisy signals.
;PERFORMANCE vs. ACCURACY
;Reducing the samples per second should improve the performance and decrease
;the accuracy of the labels. Increasing the samples per second will do the
;opposite. The more samples checked, the longer it takes. The more samples
;checked, the more precisely the program can place the silence labels.
;my-srate-ratio determines the number of samples in my-s. Set the number after (snd-srate s)
;higher to increase the number of samples.
(defun my-s (s-in)
(setq my-srate-ratio (truncate (/ (snd-srate (mono-s s-in)) 100)))
(snd-avg (mono-s s-in) my-srate-ratio my-srate-ratio OP-PEAK)
)
;Set the silence threshold level (convert it to a linear form)
(setq thres (db-to-linear (* -1 sil-lev)))
;Store the sample rate of the sound
(setq s1-srate (snd-srate (my-s s)))
;Initialize the variable that will hold the length of the sound.
;Do not calculate it now with snd-length, because it would waste memory.
;We will calculate it later.
(setq s1-length 0)
;Initialize the silence counter
(setq sil-c 0)
;Initialize the labels variable
(setq l NIL)
;Convert the silence duration in seconds to a length in samples
(setq sil-length (* sil-dur s1-srate))
;Set the sound-start marker to -1, indicating no sound has been found yet
(setq sound-start -1)
(setq silence-start -1)
;Set the flag that says we are looking for the start of a sound (as opposed to the start of a silence)
(setq sound-search 1)
;Set the counter that counts sounds
(setq sound-count 0)
(setq label-string "")
;Define a function to add new items to the list of labels
(defun add-label (l-starttime l-endtime l-text)
(setq l (cons (list l-starttime l-endtime l-text) l))
)
;The main working part of the program, it counts
;the number of sequential samples with volume under
;the threshold. It adds to a list of markers every time
;there is a longer period of silence than the silence
;duration amount.
;It runs through a loop, adding to the list of markers (l)
;each time it finds silence.
(let (s1) ;Define s1 as a local variable to allow efficient memory use
; Get the sample into s1, then free s to save memory
(setq s1 (my-s s))
(setq s nil)
;Capture the result of this "do" loop, because we need the sound's length
;in samples.
(setq s1-length
;Keep repeating, incrementing the counter and getting another sample
;each time through the loop.
(do ((n 1 (+ n 1)) (v (snd-fetch s1) (setq v (snd-fetch s1))))
;Exit when we run out of samples (v is nil) and return the number of
;samples processed (n)
((not v) n)
;Start the execution part of the do loop
;if found silence, increment the silence counter; if silence-start is not already > -1, set the start of silence to the current sample number (n)
(if (< v thres)
(progn
(setq sil-c (+ sil-c 1))
(if (= silence-start -1) (setq silence-start n))
)
)
;if found sound, and sound-search is 1, mark the start of the sound and change sound-search to 0 (look for silence next)
(if (and (>= v thres) (= sound-search 1))
(progn
(setq sound-search 0)
(setq sound-start n)
(setq sound-count (1+ sound-count))
)
)
;if found silence, and silence-counter is long enough, and sound-search is 0, and sound-start is not -1, and silence-start is not -1, that indicates the end of a sound (for which we have already found the beginning), which we should now label
(if (and (< v thres) (= sound-search 0) (/= sound-start -1) (> sil-c sil-length) (/= silence-start -1))
(progn
(setq sound-search 1)
(setq sil-c 0)
;Create the label text
(setq label-string (strcat label-string (format nil "~A" sound-count)))
(add-label (- (/ sound-start s1-srate) labelbeforedur) (+ (/ silence-start s1-srate) labelafterdur) label-string)
(setq label-string "")
(setq silence-start -1)
)
)
;if found sound, reset the silence-counter and silence-start
(if (>= v thres)
(progn
(setq sil-c 0)
(setq silence-start -1)
)
)
)
)
)
;if we're still looking for the end of a sound at the end of the file, end the sound at the end of the file
(if (= sound-search 0)
(progn
(setq label-string (strcat label-string (format nil "~A" sound-count)))
(add-label (- (/ sound-start s1-srate) labelbeforedur) (/ s1-length s1-srate) label-string)
)
)
;If no sound markers were found, return a message
;Otherwise, if some sounds were found, also optionally place a label at the end of the file.
(if (null l)
(setq l "No sounds found. Try reducing the silence\nlevel and minimum silence duration.")
(if (= finallabel 1) (add-label (/ s1-length s1-srate) (/ s1-length s1-srate) "[End]"))
)
l