the csound orchestra semi-colon begins a commentsemi-colon begins a comment csound ignorescsound...

The Csound OrchestraThe Csound OrchestraThe Csound OrchestraThe Csound Orchestra

• semi-colon begins a comment semi-colon begins a comment • Csound ignoresCsound ignores

• everything on the line after the semi-colon everything on the line after the semi-colon • blank lines blank lines

• instr 1 — gives instrument number instr 1 — gives instrument number • first line of instrument designfirst line of instrument design

Assembly Language-Style SyntaxAssembly Language-Style SyntaxAssembly Language-Style SyntaxAssembly Language-Style Syntax

• each line of instrument — one operation each line of instrument — one operation • result variable — left column result variable — left column

• except with operations such as except with operations such as outout which do not which do not have a resulthave a result

• the operation (an "opcode") — second column the operation (an "opcode") — second column • tells Csound which unit generator to usetells Csound which unit generator to use

• one or more arguments — third column one or more arguments — third column

resultresult opcodeopcode argument1, argument2, ... argument1, argument2, ...

outout signalsignal

Initial VariablesInitial VariablesInitial VariablesInitial Variables• begin with the letter "i" begin with the letter "i" • ifreqifreq and and iwtnumiwtnum are initial variables are initial variables • set their values at the beginning of each note set their values at the beginning of each note

— they are single numbers — they are single numbers • remain constant for the note duration — BUT remain constant for the note duration — BUT

• additional statements can revise them additional statements can revise them • example: multiplying iamp by .5 cuts the example: multiplying iamp by .5 cuts the

amplitude in halfamplitude in half

iampiamp == p4p4

iampiamp == iamp * .5 iamp * .5

Initial VariablesInitial VariablesInitial VariablesInitial Variables• iampiamp — constant representing the maximum — constant representing the maximum

amplitude of note (value from parameter amplitude of note (value from parameter field 4 in the score) field 4 in the score)

• ifreqifreq — the frequency of the note (p5) — the frequency of the note (p5) • iattackiattack — the attack time in seconds (p6) — the attack time in seconds (p6) • idecayidecay — the decay time (p7) — the decay time (p7) • isustainisustain — sustain time — duration — sustain time — duration

between attack and decay between attack and decay • isustainisustain definition must come after definition must come after iattackiattack

and and idecayidecay

Amplitude EnvelopesAmplitude EnvelopesAmplitude EnvelopesAmplitude Envelopes

• can fade the waveform incan fade the waveform in• time-varying scalers that allow waveforms time-varying scalers that allow waveforms

to fade in or out and vary in overall to fade in or out and vary in overall amplitudeamplitude

amplitude envelope

ampenvampenv linseglinseg 0,idur,iamp0,idur,iamp


• Output signal in first .1 seconds:Output signal in first .1 seconds:


• [i:80][i:80] Output signal over full note duration: Output signal over full note duration:


• [i:81] [i:81] add decay to the envelope to control add decay to the envelope to control how the note fades out how the note fades out

ampenvampenv linseglinseg 0,iattack,iamp,idecay,00,iattack,iamp,idecay,0

0

iamp

iattack idecay

Audio Rate VariablesAudio Rate VariablesAudio Rate VariablesAudio Rate Variables

• [i:82] [i:82] ampenvampenv — amplitude envelope — amplitude envelope controlling how the note fades in and out controlling how the note fades in and out • linseglinseg arguments — line segment breakpoints arguments — line segment breakpoints • shaped by attack and decay time values in shaped by attack and decay time values in

Csound scoreCsound score

ampenvampenv linseglinseg 0,iattack,iamp,isustain,iamp,idecay,00,iattack,iamp,isustain,iamp,idecay,0

0

iamp

iattack isustain idecay


; amplitude envelope and signal:; amplitude envelope and signal:ampenvampenv linseglinseg 0,iattack,1,isustain,1,idecay,0,1,00,iattack,1,isustain,1,idecay,0,1,0asigasig oscilioscili iamp, ifreq, iwave iamp, ifreq, iwave ; generate signal; generate signal

outout asig * ampenvasig * ampenv ; output signal; output signalendinendin ; end of instrument; end of instrument

• oscilioscili statement generates the output signal statement generates the output signal ((asigasig) ) • first argument — amplitude (first argument — amplitude (iampiamp) ) • second argument — frequency (second argument — frequency (ifreqifreq) ) • third argument — wavetable number (1) third argument — wavetable number (1)

• outout writes asig to the soundfile writes asig to the soundfile • endinendin turns off the instrument design turns off the instrument design

oscilioscilioscilioscili• a basic Csound unit generator which performs a basic Csound unit generator which performs

wavetable lookupwavetable lookup• arguments: arguments:

• xampxamp — the note's maximum amplitude — the note's maximum amplitude • xfreqxfreq — frequency — frequency • iwtnumiwtnum — wavetable number — wavetable number • example: example:

asigasig oscilioscili ampenv, ifreq, iwtnum ampenv, ifreq, iwtnum

• first letter of each result or argument name first letter of each result or argument name • specifies whether the variable remains constant or specifies whether the variable remains constant or

varies over timevaries over time

Audio Rate VariablesAudio Rate VariablesAudio Rate VariablesAudio Rate Variables• change every sampling period change every sampling period • always begin with the letter "a" always begin with the letter "a" • made of many numbers — used for time-made of many numbers — used for time-

varying variables such as signals and varying variables such as signals and envelopes envelopes • the result the result ampenvampenv in the example is an audio rate in the example is an audio rate

variable:variable:

ampenv linseg 0, iattack, iamp, isustain, iamp, idecay, 0ampenv linseg 0, iattack, iamp, isustain, iamp, idecay, 0

0

iamp

iattack isustain idecay

Control Rate VariablesControl Rate VariablesControl Rate VariablesControl Rate Variables• change once every control period change once every control period • always begin with "k" always begin with "k"

• change more slowly than audio rate variables change more slowly than audio rate variables • control rate usually about 1/10 of audio ratecontrol rate usually about 1/10 of audio rate

• not as precise as audio rate variables, but can not as precise as audio rate variables, but can efficiently represent slowly varying functions such efficiently represent slowly varying functions such as some amplitude envelopesas some amplitude envelopes

• Not as common in recent years with improved CPU Not as common in recent years with improved CPU speeds. Now many Csound user only use audio speeds. Now many Csound user only use audio rate variables for time-varying variables. rate variables for time-varying variables.

kfreq =kfreq = ifreq + kvibifreq + kvib

The Csound OrchestraThe Csound OrchestraThe Csound OrchestraThe Csound Orchestra;sinewave.orc;sinewave.orc ; name of orchestra; name of orchestrasr=22050sr=22050 ; sampling rate; sampling ratekr=2205kr=2205 ; control rate; control rateksmps=10ksmps=10 ; samples/control per.; samples/control per.nchnls=1nchnls=1 ; 1 channel playback; 1 channel playback;-----------------------------------------------------;-----------------------------------------------------instr 1instr 1 ; beginning of instr.; beginning of instr.iduridur == p3p3 ; duration; duration iampiamp == p4p4 ; maximum amplitude; maximum amplitude ifreqifreq == p5p5 ; frequency in Hertz; frequency in Hertziattackiattack == p6p6 ; attack time dur.; attack time dur.idecayidecay == p7p7 ; decay time dur.; decay time dur.isustainisustain == idur - iattack - idecay idur - iattack - idecay ; remaining dur.; remaining dur.iwaveiwave == 11 ; use wavetable 1; use wavetable 1

continued on following slide ...


; amplitude envelope and signal:; amplitude envelope and signal:

ampenvampenv linseglinseg 0, iattack, 1, isustain, 1, idecay, 00, iattack, 1, isustain, 1, idecay, 0

asigasig oscilioscili iamp, ifreq, iwave iamp, ifreq, iwave ; generate signal; generate signal

outout asig * ampenvasig * ampenv ; output signal; output signal

endinendin ; end of instrument; end of instrument

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