Description

This subroutine generates functions of different windows. These windows are usually used for spectrum analysis or for grain envelopes.

Syntax

f # time size 20 window max [opt]

Initialization

size -- number of points in the table. Must be a power of 2 ( + 1).

window -- Type of window to generate:

max -- For negative p4 this will be the absolute value at window peak point. If p4 is positive or p4 is negative and p6 is missing the table will be post-rescaled to a maximum value of 1.

opt -- Optional argument required by the Gaussian window and the Kaiser window.

Examples

f       1       0       1024    20      5

This creates a function which contains a 4 - term Blackman - Harris window with maximum value of 1.

f       1       0       1024    -20     2       456

This creates a function that contains a Hanning window with a maximum value of 456.

f       1       0       1024    -20     1

This creates a function that contains a Hamming window with a maximum value of 1.

f       1       0       1024    20      7       1       2

This creates a function that contains a Kaiser window with a maximum value of 1. The extra argument specifies how "open" the window is, for example a value of 0 results in a rectangular window and a value of 10 in a Hamming like window.

f       1       0       1024    20      6       1       2

This creates a function that contains a Gaussian window with a maximum value of 1. The extra argument specifies how broad the window is, as the standard deviation of the curve; in this example the s.d. is 2. The default value is 1.

For all diagrams, see Window Functions

Here is an example of the GEN20 routine. It uses the file gen20.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 gen20.wav -W ;;; for file output any platform 
</CsOptions>
<CsInstruments>
 

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

instr 1 

insnd   = 10 				;"fox.wav"
ibasfrq = 44100 / ftlen(insnd)		;use original sample rate of insnd file 

kamp   expseg .001, p3/2, .7, p3/2, .8	;envelope
kpitch line ibasfrq, p3, ibasfrq * .8 
kdens  line 600, p3, 10 
kaoff  line 0, p3, .1
kpoff  line 0, p3, ibasfrq * .5 
kgdur  line .04, p3, .001		;shorten duration of grain during note
imaxgdur =  .5 
igfn = p4 				;different windows
asigL  grain kamp, kpitch, kdens, kaoff, kpoff, kgdur, insnd, igfn, imaxgdur, 0.0 
asigR  grain kamp, kpitch, kdens, kaoff, kpoff, kgdur, insnd, igfn, imaxgdur, 0.0 
       outs asigL, asigR

endin 
</CsInstruments>
<CsScore>
 
f1  0 512  20 2		;Hanning window 
f2  0 512  20 6 1	;Gaussian window 
f10 0 16384 1 "fox.wav" 0 0 0 

i1 0 5 1		;use Hanning window 
i1 + 5 2		;use Gaussian window
e 
</CsScore>
</CsoundSynthesizer>

These are the diagrams of the waveforms of the GEN20 routines, as used in the example:

f 1 0 512 20 2 - Hanning window

f 2 0 512 20 6 1 - Gaussian window

Credits

New in Csound version 3.2

Optional argument to Gaussian added in 5.10