Skip to content

pvsifd

Instantaneous Frequency Distribution, magnitude and phase analysis.

The pvsifd opcode takes an input a-rate signal and performs an Instantaneous Frequency, magnitude and phase analysis, using the STFT and pvsifd (Instantaneous Frequency Distribution), as described in Lazzarini et al, "Time-stretching using the Instantaneous Frequency Distribution and Partial Tracking", Proc.of ICMC05, Barcelona. It generates two PV streaming signals, one containing the amplitudes and frequencies (a similar output to pvsanal) and another containing amplitudes and unwrapped phases.

Syntax

ffr, fphs pvsifd ain, ifftsize, ihopsize, iwintype [,iscal]

Performance

ffr -- output pv stream in AMP_FREQ format

fphs -- output pv stream in AMP_PHASE format

ifftsize -- FFT analysis size, must be power-of-two and integer multiple of the hopsize.

ihopsize -- hopsize in samples

iwintype -- window type (O: Hamming, 1: Hanning)

iscal -- amplitude scaling (defaults to 1).

⚠ 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 pvsifd opcode. It uses the file pvsifd.csd.

Example of the pvsifd opcode.
 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
<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 pvsifd.wav -W ;;; for file output any platform
</CsOptions>
<CsInstruments>

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

instr 1

ifftsize    =   p4
ihopsize    =   p5
ain     diskin2  "drumsMlp.wav", 1, 0, 1                  
fs1,fsi2 pvsifd  ain, ifftsize, ihopsize, 1             ; pvsifd analysis
fst     partials fs1, fsi2, .1, 1,3, 500        ; partial tracking
aout    resyn    fst, 1, 1.5, 500, 1            ; resynthesis (up a 5th)
        outs    aout, aout

endin
</CsInstruments>
<CsScore>
;sine
f1 0 4096 10 1
;           size    hop
i 1 0 2     2048    512  
i 1 3 2     1024    256      
e
</CsScore>
</CsoundSynthesizer>

The example above shows the pvsifd analysis feeding into partial tracking and cubic-phase additive resynthesis with pitch shifting.

See also

Tools for Real-time Spectral Processing (pvs opcodes)

Credits

Author: Victor Lazzarini
June 2005

New plugin in version 5

November 2004.