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# adsynt

adsynt -- Performs additive synthesis with an arbitrary number of partials, not necessarily harmonic.

## Description

Performs additive synthesis with an arbitrary number of partials, not necessarily harmonic.

## Syntax

ar adsynt kamp, kcps, iwfn, ifreqfn, iampfn, icnt [, iphs]

## Initialization

iwfn -- 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.

## Performance

kamp -- 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.

## Examples

Here is an example of the adsynt opcode. It uses the files adsynt.orc and adsynt.sco. These 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.

Example 1. Example of the adsynt opcode.

    /* adsynt.orc */
    ; Initialize the global variables.
    sr = 44100
    kr = 4410
    ksmps = 10
    nchnls = 1

    ; Generate a sinewave table.
    giwave ftgen 1, 0, 1024, 10, 1
    ; Generate two empty tables for adsynt.
    gifrqs ftgen 2, 0, 32, 7, 0, 32, 0
    ; A table for freqency and amp parameters.
    giamps ftgen 3, 0, 32, 7, 0, 32, 0

    ; Generates parameters at init time
    instr 1
      ; Generate 10 voices.
      icnt = 10
      ; Init loop index.
      index = 0

    ; Loop only executed at init time.
    loop:
      ; Define non-harmonic partials.
      ifreq pow index + 1, 1.5
      ; Define amplitudes.
      iamp = 1 / (index+1)
      ; Write to tables.
      tableiw ifreq, index, gifrqs
      ; Used by adsynt.
      tableiw iamp, index, giamps

      index = index + 1
      ; Do loop/
      if (index < icnt) igoto loop

      asig adsynt 5000, 150, giwave, gifrqs, giamps, icnt
      out asig
    endin

    ; Generates parameters every k-cycle.
    instr 2
      ; Generate 10 voices.
      icnt = 10
      ; Reset loop index.
      kindex = 0

    ; Loop executed every k-cycle.
    loop:
      ; Generate lfo for frequencies.
      kspeed  pow kindex + 1, 1.6
      ; Individual phase for each voice.
      kphas phasorbnk kspeed * 0.7, kindex, icnt
      klfo table kphas, giwave, 1
      ; Arbitrary parameter twiddling...
      kdepth pow 1.4, kindex
      kfreq pow kindex + 1, 1.5
      kfreq = kfreq + klfo*0.006*kdepth

      ; Write freqs to table for adsynt.
      tablew kfreq, kindex, gifrqs

      ; Generate lfo for amplitudes.
      kspeed  pow kindex + 1, 0.8
      ; Individual phase for each voice.
      kphas phasorbnk kspeed*0.13, kindex, icnt, 2
      klfo table kphas, giwave, 1
      ; Arbitrary parameter twiddling...
      kamp pow 1 / (kindex + 1), 0.4
      kamp = kamp * (0.3+0.35*(klfo+1))

      ; Write amps to table for adsynt.
      tablew kamp, kindex, giamps

      kindex = kindex + 1
      ; Do loop.
      if (kindex < icnt) kgoto loop

      asig adsynt 5000, 150, giwave, gifrqs, giamps, icnt
      out asig
    endin
    /* adsynt.orc */

    /* adsynt.sco */
    ; Play Instrument #1 for 2.5 seconds.
    i 1 0 2.5
    ; Play Instrument #2 for 2.5 seconds.
    i 2 3 2.5
    e
    /* adsynt.sco */

## Credits

Author: Peter Neubäcker
Munich, Germany
August, 1999

New in Csound version 3.58

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