Skip to content

grain2

Easy-to-use granular synthesis texture generator.

Generate granular synthesis textures. grain2 is simpler to use, but grain3 offers more control.

Syntax

ares grain2 kcps, kfmd, kgdur, iovrlp, kfn, iwfn [, irpow] \
            [, iseed] [, imode]

Initialization

iovrlp -- (fixed) number of overlapping grains.

iwfn -- function table containing window waveform (Use GEN20 to calculate iwfn).

irpow (optional, default=0) -- this value controls the distribution of grain frequency variation. If irpow is positive, the random distribution (x is in the range -1 to 1) is

abs(x) ^ ((1 / irpow) - 1);

for negative irpow values, it is 

(1 - abs(x)) ^ ((-1 / irpow) - 1)

Setting irpow to -1, 0, or 1 will result in uniform distribution (this is also faster to calculate). The image below shows some examples for irpow. The default value of irpow is 0.

[A graph of distributions for different values of .]
A graph of distributions for different values of .

iseed (optional, default=0) -- seed value for random number generator (positive integer in the range 1 to 2147483646 (231 - 2)). Zero or negative value seeds from current time (this is also the default).

imode (optional default=0) -- sum of the following values:

  • 8: interpolate window waveform (slower).
  • 4: do not interpolate grain waveform (fast, but lower quality).
  • 2: grain frequency is continuously modified by kcps and kfmd (by default, each grain keeps the frequency it was launched with). This may be slower at high control rates.
  • 1: skip initialization.

Performance

ares -- output signal.

kcps -- grain frequency in Hz.

kfmd -- random variation (bipolar) in grain frequency in Hz.

kgdur -- grain duration in seconds. kgdur also controls the duration of already active grains (actually the speed at which the window function is read). This behavior does not depend on the imode flags.

kfn -- function table containing grain waveform. Table number can be changed at k-rate (this is useful to select from a set of band-limited tables generated by GEN30, to avoid aliasing).

📝 Note

grain2 internally uses the same random number generator as rnd31. So reading its documentation is also recommended.

Examples

Here is an example of the grain2 opcode. It uses the file grain2.csd.

Example of the grain2 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
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
<CsoundSynthesizer>
<CsOptions>
; Select audio/midi flags here according to platform
; Audio out   Audio in    No messages
-odac           -iadc     -d     ;;;RT audio I/O
; For Non-realtime ouput leave only the line below:
; -o grain2.wav -W ;;; for file output any platform
</CsOptions>
<CsInstruments>

sr      =  48000
kr      =  750
ksmps   =  64
nchnls  =  2

/* square wave */
i_      ftgen 1, 0, 4096, 7, 1, 2048, 1, 0, -1, 2048, -1
/* window */
i_      ftgen 2, 0, 16384, 7, 0, 4096, 1, 4096, 0.3333, 8192, 0
/* sine wave */
i_      ftgen 3, 0, 1024, 10, 1
/* room parameters */
i_      ftgen 7, 0, 64, -2, 4, 50, -1, -1, -1, 11,                      \
                            1, 26.833, 0.05, 0.85, 10000, 0.8, 0.5, 2,  \
                            1,  1.753, 0.05, 0.85,  5000, 0.8, 0.5, 2,  \
                            1, 39.451, 0.05, 0.85,  7000, 0.8, 0.5, 2,  \
                            1, 33.503, 0.05, 0.85,  7000, 0.8, 0.5, 2,  \
                            1, 36.151, 0.05, 0.85,  7000, 0.8, 0.5, 2,  \
                            1, 29.633, 0.05, 0.85,  7000, 0.8, 0.5, 2

ga01  init 0

/* generate bandlimited square waves */

i0     =  0
loop1:
imaxh  =  sr / (2 * 440.0 * exp(log(2.0) * (i0 - 69) / 12))
i_     ftgen i0 + 256, 0, 4096, -30, 1, 1, imaxh
i0     =  i0 + 1
       if (i0 < 127.5) igoto loop1

       instr 1

p3     =  p3 + 0.2

/* note velocity */
iamp   =  0.0039 + p5 * p5 / 16192
/* vibrato */
kcps   oscili 1, 8, 3
kenv   linseg 0, 0.05, 0, 0.1, 1, 1, 1
/* frequency */
kcps   =  (kcps * kenv * 0.01 + 1) * 440 * exp(log(2) * (p4 - 69) / 12)
/* grain ftable */
kfn    =  int(256 + 69 + 0.5 + 12 * log(kcps / 440) / log(2))
/* grain duration */
kgdur  port 100, 0.1, 20
kgdur  =  kgdur / kcps

a1     grain2 kcps, kcps * 0.02, kgdur, 50, kfn, 2, -0.5, 22, 2
a1     butterlp a1, 3000
a2     grain2 kcps, kcps * 0.02, 4 / kcps, 50, kfn, 2, -0.5, 23, 2
a2     butterbp a2, 12000, 8000
a2     butterbp a2, 12000, 8000
aenv1  linseg 0, 0.01, 1, 1, 1
aenv2  linseg 3, 0.05, 1, 1, 1
aenv3  linseg 1, p3 - 0.2, 1, 0.07, 0, 1, 0

a1     =  aenv1 * aenv3 * (a1 + a2 * 0.7 * aenv2)

ga01   =  ga01 + a1 * 10000 * iamp

       endin

/* output instr */

       instr 81

i1     =  0.000001
aLl, aLh, aRl, aRh  spat3di ga01 + i1*i1*i1*i1, 3.0, 4.0, 0.0, 0.5, 7, 4
ga01   =  0
aLl    butterlp aLl, 800.0
aRl    butterlp aRl, 800.0

       outs aLl + aLh, aRl + aRh

       endin


</CsInstruments>
<CsScore>

t 0 60

i 1 0.0 1.3 60 127
i 1 2.0 1.3 67 127
i 1 4.0 1.3 64 112
i 1 4.0 1.3 72 112

i 81 0 6.4

e


</CsScore>
</CsoundSynthesizer>

See Also

Granular Synthesis

Credits

Author: Istvan Varga

New in version 4.15

Updated April 2002 by Istvan Varga