50 lines
1.9 KiB
Scheme
50 lines
1.9 KiB
Scheme
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;; (Packfft chain bufsize frombin tobin zeroothers magsphases)
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;; Pack separate demand-rate fft bin streams into an fft chain buffer
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;; Takes a length-prefixed array of magnitudes and phases, and packs
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;; them into an fft buffer ready for transforming back into
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;; time-domain audio using Ifft.
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;; Most people won't need to use this directly - instead, use
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;; pvcollect, pvcalc, or pvcalc2.
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;; The input data is magsphases, which should be a flat array
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;; containing magnitude and phase of all bins in ascending order.
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;; e.g. [mag0, phase0, mag1, phase1, mag2, phase2, ... magN, phaseN]
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;; This input is typically demand-rate.
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;; This is technically similar to demand or duty in that it calls
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;; demand-rate UGens further up the graph to process the values,
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;; eventually calling Unpackfft. These two ends of the process must in
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;; most cases see the same chain...! Otherwise behaviour is undefined
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;; and, who knows, possibly unpleasant.
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;; frombin and tobin allow you to fill the supplied data only into a
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;; subset of the fft bins (i.e. a single delimited frequency band),
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;; set zeroothers to 1 to zero all the magnitudes outside this band
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;; (otherwise they stay intact).
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;; For usage examples, see Unpackfft, but also pvcollect, pvcalc,
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;; pvcalc2.
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;; Here's an unusual example which uses Packfft without using
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;; Unpackfft first - essentially creating our fft data from scratch.
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(with-sc3
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(lambda (fd)
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(send fd (b-alloc 10 512 1))))
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(let* ((n 100)
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(n* (enum-from-to 1 n))
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(m1 (map (lambda (_) (range (f-sin-osc kr (exp-rand 0.1 1) 0) 0 1)) n*))
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(square (lambda (a) (* a a)))
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(m2 (map mul m1 (map square (iota n 1.0 (- (/ 1.0 n))))))
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(i (map (lambda (_) (lf-pulse kr (pow 2 (i-rand -3 5)) 0 0.3)) n*))
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(m3 (map mul m2 i))
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(p (replicate n 0.0))
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(c1 (fft* 10 (f-sin-osc ar 440 0)))
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(c2 (pack-fft c1 512 0 (- n 1) 1 (packfft-data m3 p)))
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(s (ifft* c2)))
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(audition (out 0 (mce2 s s))))
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