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Diffstat (limited to 'lib/reverse.lsp')
| -rw-r--r-- | lib/reverse.lsp | 117 |
1 files changed, 117 insertions, 0 deletions
diff --git a/lib/reverse.lsp b/lib/reverse.lsp new file mode 100644 index 0000000..f2f8e3a --- /dev/null +++ b/lib/reverse.lsp @@ -0,0 +1,117 @@ +;; reverse.lsp -- reverse sounds and files +;; + +(setf *max-reverse-samples* 25000000) ;; about 100MB of memory +(setf *reverse-blocksize* 10000) ;; how many to reverse at a time + +(defun s-reverse (snd) (multichan-expand #'nyq:s-reverse snd)) + +(defun nyq:s-reverse (snd) + (let ((now (local-to-global 0))) + (setf len (snd-length snd *max-reverse-samples*)) + (cond ((= len *max-reverse-samples*) + (error + "s-reverse cannot reverse a sound longer than *max-reverse-samples*"))) + (abs-env (at-abs now (nyq:s-reverse-from snd len))))) + +(defun nyq:s-reverse-from (snd len) + (cond ((> len *reverse-blocksize*) + (seq (nyq:reverse-some-samples snd (- len *reverse-blocksize*) + *reverse-blocksize*) + (nyq:s-reverse-from snd (- len *reverse-blocksize*)))) + (t + (nyq:reverse-some-samples snd 0 len)))) + +(defun nyq:reverse-some-samples (snd offset len) + (display "reverse-some-samples" (snd-length snd 20000) offset len) + (let ((samps (snd-samples (nyq:extract-samples snd offset len) len)) + (i2 (1- len))) + (display "reverse-some-samples" (length samps)) + (dotimes (i1 (/ len 2)) + (let ((s1 (aref samps i1)) + (s2 (aref samps i2))) + (setf (aref samps i1) s2) + (setf (aref samps i2) s1) + (setf i2 (1- i2)))) + (snd-from-array (local-to-global 0) (snd-srate snd) samps))) + +(defun nyq:extract-samples (snd offset len) + (let (start stop) + (setf start (/ offset (snd-srate snd))) + (setf stop (+ start (/ len (snd-srate snd)))) + (display "nyq:extract-samples" start stop (snd-t0 snd)) + (extract-abs start stop snd))) + +;(play (s-reverse (s-read "sample.wav"))) + +(defun s-read-reverse (filename &key (time-offset 0) (srate *sound-srate*) + (dur 10000) (nchans 1) (format *default-sf-format*) + (mode *default-sf-mode*) (bits *default-sf-bits*) + (endian nil)) + (let (fsrate fdur channels rslt) + ;; first, read the sound just to get the duration and rate of the file + (setf rslt (s-read filename :time-offset time-offset :srate srate :dur dur + :nchans nchans :format format :mode mode + :bits bits :endian endian)) + (if (null rslt) (error "s-read-reverse could not open file" filename)) + (setf channels (cadr *rslt*)) + (setf *rslt* (cddddr *rslt*)) + (setf fsrate (cadr *rslt*)) + (display "s-read-reverse" filename srate channels) + (setf fdur (caddr *rslt*)) + (setf time-offset (max 0 (min fdur time-offset))) + (setf dur (max 0 (min (- fdur time-offset) dur))) + (cond ((> channels 1) + (setf rslt (make-array channels)) + (dotimes (i channels) + (setf (aref rslt i) + (nyq:s-reverse-file filename time-offset fsrate dur + channels format mode bits endian i))) + rslt) + (t (nyq:s-reverse-file filename time-offset fsrate dur + channels format mode bits endian nil))))) + + +;; nyq:s-reverse-file -- do the work of reversing one channel of a file +;; +;; if nchans > 1, chan is the channel number to read +;; +(defun nyq:s-reverse-file (filename time-offset srate dur nchans + format mode bits endian chan) + (let ((blockdur (/ *reverse-blocksize* srate))) + (if (> dur blockdur) + (seq (nyq:reverse-some-samples + (nyq:s-read-chan filename + (+ time-offset dur (- blockdur)) + srate (/ *reverse-blocksize* srate) + nchans format mode bits endian chan) + 0 *reverse-blocksize*) + (nyq:s-reverse-file filename time-offset srate (- dur blockdur) + nchans format mode bits endian chan)) + (nyq:s-read-chan filename time-offset srate dur nchans format + mode bits endian chan)))) + + +;; nyq:s-read-chan -- grab some samples from one channel of a file +;; +(defun nyq:s-read-chan (filename time-offset srate dur nchans format + mode bits endian chan) + (let (rslt) + (setf rslt + (if (= nchans 1) + (s-read filename :time-offset time-offset :srate srate + :dur dur :nchans nchans :format format :mode mode + :bits bits :endian endian) + (aref (s-read filename :time-offset time-offset :srate srate + :dur dur :nchans nchans :format format :mode mode + :bits bits :endian endian) + chan))) + (if (not rslt) (error "nyq:s-read-chan could not read part of file" filename)) + rslt)) + + +;(play (s-read-reverse "sample.wav")) +;(play (s-read-reverse "test.wav")) + + +
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