Csound has a default system for instrument triggering via midi. Provided a midi keyboard has been connected and the appropriate commmand line flags for midi input have been set (see configuring midi for further information) or the appropriate settings have been made in QuteCsound's configuration menu, then midi notes received on midi channel 1 will trigger instrument 1, notes on channel 2 will trigger instrument 2 and so on. Instruments will turn on and off in sympathy with notes being pressed and released on the midi keyboard and Csound will correctly unravel polyphonic layering and turn on and off only the correct layer of the same instrument begin played. Midi activated notes can be thought of as 'held' notes, similar to notes activated in the score with a negative duration (p3). Midi activated notes will sustain indefinitely as long as the performance time will allow until a corresponding note off has been received - this is unless this infinite p3 duration is overwritten within the instrument itself by p3 begin explicitly defined.
The following example confirms this default mapping of midi channels to instruments. You will need a midi keyboard that allows you to change the midi channel on which it is transmmitting. Besides a written confirmation to the console of which instrument is begin triggered, there is an audible confirmation in that instrument 1 plays single pulses, instrument 2 plays sets of two pulses and instrument 3 plays sets of three pulses. The example does not go beyond three instruments. If notes are received on midi channel 4 and above, because corresonding instruments do not exist, notes on any of these channels will be directed to instrument 1.
EXAMPLE 07B01_MidiInstrTrigger.csd
<CsoundSynthesizer>
<CsOptions>
-Ma -odac -m0
;activates all midi devices, real time sound output, and suppress note printings
</CsOptions>
<CsInstruments>
sr = 44100
ksmps = 32
nchnls = 1
0dbfs = 1
gisine ftgen 0,0,2^12,10,1
instr 1 ; 1 impulse (midi channel 1)
prints "instrument/midi channel: %d%n",p1 ; print instrument number to terminal
reset: ; label 'reset'
timout 0, 1, impulse ; jump to 'impulse' for 1 second
reinit reset ; reninitialise pass from 'reset'
impulse: ; label 'impulse'
aenv expon 1, 0.3, 0.0001 ; a short percussive envelope
aSig poscil aenv, 500, gisine ; audio oscillator
out aSig ; audio to output
endin
instr 2 ; 2 impulses (midi channel 2)
prints "instrument/midi channel: %d%n",p1
reset:
timout 0, 1, impulse
reinit reset
impulse:
aenv expon 1, 0.3, 0.0001
aSig poscil aenv, 500, gisine
a2 delay aSig, 0.15 ; short delay adds another impulse
out aSig+a2 ; mix two impulses at output
endin
instr 3 ; 3 impulses (midi channel 3)
prints "instrument/midi channel: %d%n",p1
reset:
timout 0, 1, impulse
reinit reset
impulse:
aenv expon 1, 0.3, 0.0001
aSig poscil aenv, 500, gisine
a2 delay aSig, 0.15 ; delay adds a 2nd impulse
a3 delay a2, 0.15 ; delay adds a 3rd impulse
out aSig+a2+a3 ; mix the three impulses at output
endin
</CsInstruments>
<CsScore>
f 0 300
e
</CsScore>
<CsoundSynthesizer>
We can use the massign opcode, which is used just after the header statement, to explicitly map midi channels to specific instruments and thereby overrule Csound's default mappings. massign takes two input arguments, the first defines the midi channel to be redirected and the second defines which instrument it should be directed to. The following example is identical to the previous one except that the massign statements near the top of the orchestra jumbles up the default mappings. Midi notes on channel 1 will be mapped to instrument 3, notes on channel 2 to instrument 1 and notes on channel 3 to instrument 2. Undefined channel mappings will be mapped according to the default arrangement and once again midi notes on channels for which an instrument does not exist will be mapped to instrument 1.
EXAMPLE 07B02_massign.csd
<CsoundSynthesizer>
<CsOptions>
-Ma -odac -m0
; activate all midi devices, real time sound output, and suppress note printing
</CsOptions>
<CsInstruments>
; Example by Iain McCurdy
sr = 44100
ksmps = 32
nchnls = 1
0dbfs = 1
gisine ftgen 0,0,2^12,10,1
massign 1,3 ; channel 1 notes directed to instr 3
massign 2,1 ; channel 2 notes directed to instr 1
massign 3,2 ; channel 3 notes directed to instr 2
instr 1 ; 1 impulse (midi channel 1)
iChn midichn ; discern what midi channel
prints "channel:%d%tinstrument: %d%n",iChn,p1 ; print instr num and midi channel
reset: ; label 'reset'
timout 0, 1, impulse ; jump to 'impulse' for 1 second
reinit reset ; reninitialize pass from 'reset'
impulse: ; label 'impulse'
aenv expon 1, 0.3, 0.0001 ; a short percussive envelope
aSig poscil aenv, 500, gisine ; audio oscillator
out aSig ; send audio to output
endin
instr 2 ; 2 impulses (midi channel 2)
iChn midichn
prints "channel:%d%tinstrument: %d%n",iChn,p1
reset:
timout 0, 1, impulse
reinit reset
impulse:
aenv expon 1, 0.3, 0.0001
aSig poscil aenv, 500, gisine
a2 delay aSig, 0.15 ; delay generates a 2nd impulse
out aSig+a2 ; mix two impulses at the output
endin
instr 3 ; 3 impulses (midi channel 3)
iChn midichn
prints "channel:%d%tinstrument: %d%n",iChn,p1
reset:
timout 0, 1, impulse
reinit reset
impulse:
aenv expon 1, 0.3, 0.0001
aSig poscil aenv, 500, gisine
a2 delay aSig, 0.15 ; delay generates a 2nd impulse
a3 delay a2, 0.15 ; delay generates a 3rd impulse
out aSig+a2+a3 ; mix three impulses at output
endin
</CsInstruments>
<CsScore>
f 0 300
e
</CsScore>
<CsoundSynthesizer>
massign also has a couple of additional functions that may come in useful. A channel number of zero is interpreted as meaning 'any'. The following instruction will map notes on any and all channels to instrument 1.
massign 0,1
An instrument number of zero is interpreted as meaning 'none' so the following instruction will instruct Csound to ignore triggering for notes received on all channels.
massign 0,0
The above feature is useful when we want to scan midi data from an already active instrument using the midiin opcode, as we did in EXAMPLE 0701.csd.
Csound's event/event_i opcode (see the Triggering Instrument Events chapter) makes it possible to trigger any other instrument from a midi-triggered one. As you can assign a fractional number to an instrument, you can distinguish the single instances from each other. Below is an example of using fractional instrument numbers.
EXAMPLE 07B03_MidiTriggerChain.csd
<CsoundSynthesizer>
<CsOptions>
-Ma
</CsOptions>
<CsInstruments>
;Example by Joachim Heintz, using code of Victor Lazzarini
sr = 44100
ksmps = 32
nchnls = 1
0dbfs = 1
massign 0, 1 ;assign all incoming midi to instr 1
instr 1 ;global midi instrument, calling instr 2.cc.nnn
;(c=channel, n=note number)
inote notnum ;get midi note number
ichn midichn ;get midi channel
instrnum = 2 + ichn/100 + inote/100000 ;make fractional instr number
; -- call with indefinite duration
event_i "i", instrnum, 0, -1, ichn, inote
kend release ;get a "1" if instrument is turned off
if kend == 1 then
event "i", -instrnum, 0, 1 ;then turn this instance off
endif
endin
instr 2
ichn = int(frac(p1)*100)
inote = round(frac(frac(p1)*100)*1000)
prints "instr %f: ichn = %f, inote = %f%n", p1, ichn, inote
printks "instr %f playing!%n", 1, p1
endin
</CsInstruments>
<CsScore>
f 0 36000
e
</CsScore>
</CsoundSynthesizer>
This example merely demonstrates a technique for passing information about MIDI channel and note number from the directly triggered instrument to a sub-instrument. A practical application for this would be for creating keygroups - triggering different instruments by playing in different regions of the keyboard. In this case you could change just the line:
instrnum = 2 + ichn/100 + inote/100000
to this:
if inote < 48 then instrnum = 2 elseif inote < 72 then instrnum = 3 else instrnum = 4 endif instrnum = instrnum + ichn/100 + inote/100000
In this case for any key below C3 instrument 2 will be called, for any key between C3 and B4 instrument 3, and for any higher key instrument 4.
Using this multiple triggering you are also able to trigger more than one instrument at the same time (which is not possible using the massign opcode). Here is an example using a user defined opcode (see the UDO chapter of this manual):
EXAMPLE 07B04_MidiMultiTrigg.csd
<CsoundSynthesizer>
<CsOptions>
-Ma
</CsOptions>
<CsInstruments>
;Example by Joachim Heintz, using code of Victor Lazzarini
sr = 44100
ksmps = 32
nchnls = 1
0dbfs = 1
massign 0, 1 ;assign all incoming midi to instr 1
giInstrs ftgen 0, 0, -5, -2, 2, 3, 4, 10, 100 ;instruments to be triggered
opcode MidiTrig, 0, io
;triggers the first inum instruments in the function table ifn by a midi event,
; with fractional numbers containing channel and note number information
; -- if inum=0 or not given, all instrument numbers in ifn are triggered
ifn, inum xin
inum = (inum == 0 ? ftlen(ifn) : inum)
inote notnum
ichn midichn
iturnon = 0
turnon:
iinstrnum tab_i iturnon, ifn
if iinstrnum > 0 then
ifracnum = iinstrnum + ichn/100 + inote/100000
event_i "i", ifracnum, 0, -1
endif
loop_lt iturnon, 1, inum, turnon
kend release
if kend == 1 then
kturnoff = 0
turnoff:
kinstrnum tab kturnoff, ifn
if kinstrnum > 0 then
kfracnum = kinstrnum + ichn/100 + inote/100000
event "i", -kfracnum, 0, 1
loop_lt kturnoff, 1, inum, turnoff
endif
endif
endop
instr 1 ;global midi instrument
; -- trigger the first two instruments in the giInstrs table
MidiTrig giInstrs, 2
endin
instr 2
ichn = int(frac(p1)*100)
inote = round(frac(frac(p1)*100)*1000)
prints "instr %f: ichn = %f, inote = %f%n", p1, ichn, inote
printks "instr %f playing!%n", 1, p1
endin
instr 3
ichn = int(frac(p1)*100)
inote = round(frac(frac(p1)*100)*1000)
prints "instr %f: ichn = %f, inote = %f%n", p1, ichn, inote
printks "instr %f playing!%n", 1, p1
endin
</CsInstruments>
<CsScore>
f 0 36000
e
</CsScore>
</CsoundSynthesizer>
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