pvstrace

Process a PV stream by retaining only the N bins with the highest amplitude, zeroing the others.

Syntax

fsig pvstrace fsigin, kn
fsig, kBins[] pvstrace fsigin, kn [, isort, imin, imax]

Initialization

isort -- if nonzero, sort the reported bins in kBins by decreasing amplitude, optional (default 0, off).

imin, imax -- if nonzero, search between a min and max value (default 0, no min or max).

Performance

fsig -- output pv stream

kBins[] -- an array of size fftsize/2 + 1 values, whose first N values report the kn bin numbers retained by pvstrace. Other locations are set to 0. It can be sorted or unsorted.

fsigin -- input pv stream

kn -- number of bins to be retained

Warning

It is unsafe to use the same f-variable for both input and output of pvs opcodes. Using the same one might lead to undefined behavior on some opcodes. Use a different one on the left and right sides of the opcode.

Examples

Here is an example of the use of the pvstrace opcode. It uses the file pvstrace.csd.

<CsoundSynthesizer>
<CsOptions>
; Select audio/midi flags here according to platform
-odac  ;;;realtime audio out
;-iadc    ;;;uncomment -iadc if realtime audio input is needed too
; For Non-realtime ouput leave only the line below:
; -o pvstrace.wav -W ;;; for file output any platform
</CsOptions>
<CsInstruments>

sr = 44100
ksmps = 32
nchnls = 2
0dbfs  = 1

instr 1

kn = p4
asig  diskin2   "drumsMlp.wav", 1
fsig  pvsanal   asig, 1024, 256, 1024, 1; analyse it
ftps  pvstrace   fsig, kn               ; keep kn bins
atps  pvsynth   ftps                    ; synthesise it
      outs      atps, atps

endin
</CsInstruments>
<CsScore>

i1 0 2  5
i1 + 2  10
i1 + 2  20
i1 + 2  40
i1 + 2  80
i1 + 2  160
e
</CsScore>
</CsoundSynthesizer>

See also

Tools for Real-time Spectral Processing (pvs opcodes)

Credits

Author: Victor Lazzarini
2017

New plugin in version 6.09