The Public Csound Reference Manual Version 4.10 Signal Generators: Additive Synthesis/Resynthesis Page 37-1
37 S IGNAL G ENERATORS : A DDITIVE
The Public Csound Reference Manual Version 4.10 Signal Generators: Additive Synthesis/Resynthesis Page 37-2 kfmod is a control-rate transposition factor: a value of 1 incurs no transposition, 1.5 transposes up a perfect fifth, and .5 down an octave.
The Public Csound Reference Manual Version 4.10 Signal Generators: Additive Synthesis/Resynthesis Page 37-3
37.2 a d s y n t
ar adsyntadsyntadsyntadsynt kamp, kcps, iwfn, ifreqfn, iampfn, icnt[, iphs]
D
ESCRIPTIONPerforms additive synthesis with an arbitrary number of partials, not necessarily harmonic.
I
NITIALIZATIONiwfn – table containing a waveform, usually a sine. Table values are not interpolated for performance reasons, so larger tables provide better quality.
ifreqfn – table containing frequency values for each partial. ifreqfn may contain beginning frequency values for each partial, but is usually used for generating parameters at runtime with tablew. Frequencies must be relative to kcps. Size must be at least icnt.
iampfn – table containing amplitude values for each partial. iampfn may contain beginning amplitude values for each partial, but is usually used for generating parameters at runtime with tablew. Amplitudes must be relative to kamp. Size must be at least icnt.
icnt – number of partials to be generated
iphs – initial phase of each oscillator, if iphs = -1, initialization is skipped. If iphs > 1, all phases will be initialized with a random value.
P
ERFORMANCEkamp – amplitude of note
kcps – base frequency of note. Partial frequencies will be relative to kcps.
Frequency and amplitude of each partial is given in the two tables provided. The purpose of this opcode is to have an instrument generate synthesis parameters at k-rate and write them to global parameter tables with the tablew opcode.
E
XAMPLESThese two instruments perform additive synthesis. The output of each sounds like a Tibetan bowl. The first one is static, as parameters are only generated at init-time. In the second one, parameters are continuously changed.
gifrqs ftgenftgenftgenftgen 2, 0, 32, 7, 0, 32, 0 ; generate two emty tables
; for adsynt
giamps ftgenftgenftgenftgen 3, 0, 32, 7, 0, 32, 0 ; for freqency and amp
; parameters instr
instr instr
instr 1 ; generates parameters at init time
icnt = 10 ; generate 10 voices
index = 0 ; init loop index
The Public Csound Reference Manual Version 4.10 Signal Generators: Additive Synthesis/Resynthesis Page 37-4
loop: ; loop only executed at
; init time
ifreq powpowpowpow index + 1, 1.5 ; define non-harmonic partials iamp = 1 / (index+1) ; define amplitudes
tabtab
tabtableiwleiwleiwleiw ifreq, index, gifrqs ; write to tables tableiw
tableiw tableiw
tableiw iamp, index, giamps ; used by adsynt
index = index + 1
if if if
if (index < icnt) igotoigotoigotoigoto loop ; do loop
asig adsyntadsyntadsyntadsynt 5000, 150, giwave, gifrqs, giamps, icnt outout
outout asig endin
endin endin endin
instr instr instr
instr 2 ; generates paramaters
;
;
;
; every k-cycle
icnt = 10 ; generate 10 voices
kindex = 0 ; reset loop index
loop: ; loop executed every
; k-cycle
kspeed powpowpowpow kindex + 1, 1.6 ; generate lfo for
; frequencies
kphas phasorbnk kspeed * 0.7, kindex, icnt ; individual phase for each voice
klfo tabletabletabletable kphas, giwave, 1
kdepth powpowpowpow 1.4, kindex ; arbitrary parameter twiddling...
kfreq powpowpowpow kindex + 1, 1.5
kfreq = kfreq + klfo*0.006*kdepth tablew
tablew tablew
tablew kfreq, kindex, gifrqs ; write freqs to table for
;
;
;
; adsynt
kspeed powpowpowpow kindex + 1, 0.8 ; generate lfo for amplitudes kphas phasorbnk kspeed*0.13, kindex, icnt, 2 ; individual phase for
; each voice klfo tabletabletabletable kphas, giwave, 1
kamp powpowpowpow 1 / (kindex + 1), 0.4 ; arbitrary parameter
; twiddling...
kamp = kamp * (0.3+0.35*(klfo+1))
tablew tablew tablew
tablew kamp, kindex, giamps ; write amps to table for
;
;
;
; adsyntadsyntadsyntadsynt
kindex = kindex + 1
ifif
ifif (kindex < icnt) kgotokgotokgotokgoto loop ; do loop
giwave ftgenftgenftgenftgen 1, 0, 1024, 10, 1 ; generate a sinewave
; table
asig adsyntadsyntadsyntadsynt 5000, 150, giwave, gifrqs, giamps, icnt outout
outout asig endin
endin endin endin
A
UTHORPeter Neubäcker Munich, Germany August, 1999
New in Csound version 3.58
The Public Csound Reference Manual Version 4.10 Signal Generators: Additive Synthesis/Resynthesis Page 37-5
37.3 h s b os ci l
ar hsboscilhsboscilhsboscilhsboscil kamp, ktone, kbrite, ibasfreq, iwfn, ioctfn \\
[, ioctcnt[, iphs]]
D
ESCRIPTIONAn oscillator which takes tonality and brightness as arguments, relative to a base frequency.
I
NITIALIZATIONibasfreq – base frequency to which tonality and brighness are relative iwfn – function table of the waveform, usually a sine
ioctfn – function table used for weighting the octaves, usually something like:
f1 0 1024 -19 1 0.5 270 0.5
ioctcnt – number of octaves used for brightness blending. Must be in the range 2 to 10.
Default is 3.
iphs – initial phase of the oscillator. If iphs = -1, initialization is skipped.
P
ERFORMANCEkamp – amplitude of note
ktone – cyclic tonality parameter relative to ibasfreq in logarithmic octave, range 0 to 1, values > 1 can be used, and are internally reduced to frac(ktone).
kbrite – brightness parameter relative to ibasfreq, achieved by weighting ioctcnt octaves.
It is scaled in such a way, that a value of 0 corresponds to the orignal value of ibasfreq, 1 corresponds to one octave above ibasfreq, -2 corresponds to two octaves below ibasfreq, etc. kbrite may be fractional.
hsboscil takes tonality and brightness as arguments, relative to a base frequency
(ibasfreq). Tonality is a cyclic parameter in the logarithmic octave, brightness is realized by mixing multiple weighted octaves. It is useful when tone space is understood in a concept of polar coordinates.
Making ktone a line, and kbrite a constant, produces Risset’s glissando.
Oscillator table iwfn is always read interpolated. Performance time requires about ioctcnt * oscili.
The Public Csound Reference Manual Version 4.10 Signal Generators: Additive Synthesis/Resynthesis Page 37-6
E
XAMPLESgiwave ftgenftgenftgenftgen 1, 0, 1024, 10, 1, 1, 1, 1 ; synth wave giblend ftgenftgenftgenftgen 2, 0, 1024, -19, 1, 0.5, 270, 0.5 ; blending window
instr instr instr
instr 1 ; endless glissando ktona linelinelineline 0,10,1
asig hsboscilhsboscilhsboscilhsboscil 10000, ktona, 0, 200, giwave, giblend, 5 outout
outout asig endin
endin endin endin
instr instr instr
instr 2 ; MIDI instrument: all octaves sound alike, itona octmidioctmidioctmidioctmidi ; velocity is mapped to brightness
ibrite ampmidiampmidiampmidiampmidi 3
ibase = cpsoct(6) kenv exponexponexponexpon 20000, 1, 100
asig hsboscilhsboscilhsboscilhsboscil kenv, itona, ibrite, ibase, giwave, giblend, 5 outoutoutout asig
endin endin endin endin
A
UTHORPeter Neubäcker Munich, Germany August, 1999
New in Csound version 3.58
The Public Csound Reference Manual Version 4.10 Signal Generators: FM Synthesis Page 38-1