Noob: Basic MIDI help needed

Questions
1

Hello, I really am a beginner and have just botched my way through SC for years now. I set up a really basic midi synth and get the following error:
ERROR: Message ‘at’ not understood.
Perhaps you misspelled ‘as’, or meant to call ‘at’ on another receiver?
RECEIVER:
Symbol ‘robBasic’
ARGS:
Symbol ‘freq’
Float 82.406889 791E127C 40549A0A
Symbol ‘amp’
Float 0.163800 FD8ADABA 3FC4F765
KEYWORD ARGUMENTS:
CALL STACK:
DoesNotUnderstandError:reportError
arg this =
Nil:handleError
arg this = nil
arg error =
Thread:handleError
arg this =
arg error =
Object:throw
arg this =
Object:doesNotUnderstand
arg this = ‘robBasic’
arg selector = ‘at’
arg args = [*4]
arg kwargs = [*0]
< FunctionDef in closed FunctionDef >
arg veloc = 52
arg num = 40
arg chan = 0
arg src = -898120851
MIDIMessageDispatcher:value
arg this =
arg src = -898120851
arg chan = 0
arg num = 40
arg val = 52
Meta_MIDIIn:doNoteOnAction
arg this =
arg src = -898120851
arg chan = 0
arg num = 40
arg veloc = 52
^^ ERROR: Message ‘at’ not understood.
Perhaps you misspelled ‘as’, or meant to call ‘at’ on another receiver?
RECEIVER: robBasic

The code I am using is this:
(
var notes, on, off;

MIDIClient.init;
MIDIIn.connectAll;

notes = Array.newClear(128); // array has one slot per possible MIDI note

on = MIDIFunc.noteOn({ |veloc, num, chan, src|
notes[num] = Synth(\robBasic [\freq, num.midicps,
\amp, veloc * 0.00315]);
});

off = MIDIFunc.noteOff({ |veloc, num, chan, src|
notes[num].release;
});

q = { on.free; off.free; };
)

(
SynthDef(\robBasic,{|out= 0 freq = 440 amp = 0.1 gate=1 lforate = 4.85 lfowidth= 0.5 cutoff= 2000 rq=0.5 pan = 0.0|

var pulse, filter, env;

pulse = SinOsc.ar(freq)+ LFTri.ar(freq,0.5,0.5,0.05);
pulse = pulse*(Dust.ar(100,1,0.5)*LFPar.ar(freq,0,0.5));

env = EnvGen.ar(Env.adsr(0.9,1.0,0.8,3.0),gate,doneAction:2);

//keyboard tracking filter cutoff
filter = BLowPass4.ar(pulse,(cutoff*(env.squared))+200+freq,rq);

Out.ar(out,Pan2.ar(Mix(filter)*env*amp,pan));

}).add;
)

Can anyone explain what the error means, and what the solution is; I just cannot work it out.

2

First, I’ll link a good document for understanding errors Understanding errors | SuperCollider 3.14.1 Help

So, looking at your error, you’ll see

ERROR: Message ‘at’ not understood.
Perhaps you misspelled ‘as’, or meant to call ‘at’ on another receiver?
RECEIVER:
Symbol ‘robBasic’
ARGS:
Symbol ‘freq’

So, at some point you seem to call at on robBasic - but since robBasic is a Symbol, which does not respond to at, you’ll trigger this error message.

So, this gives us the clue to look at the regions where robBasic is used - so e.g.

notes[num] = Synth(\robBasic [\freq, num.midicps,
\amp, veloc * 0.00315]);
});

brackets [ and ] are syntactic sugar for at, so we seem to have something here which matches the error: Calling at on the symbol robBasic with arguments, freq - if you look closer, you see that you are missing a , here, so the code should be Synth(\robBasic, [\freq, num.midicps,.

I haven’t checked your code beyond that, but it could be this simple.

1 Like
3

It would appear it was that simple. Thank you so much for the explanation, and solution.

4

Btw, you can get code to look like code (monospaced font, no curly quotes) by putting three backticks before and three after:

```
code here
```

→ 

code here

If you don’t do this, then sometimes other readers would have to take time to correct some characters, such as:

“if you try to run this, it’s a syntax error”.postln;

vs

"if you try to run this, it's fine".postln;

(Because, if you don’t format your code as code, the forum software will format your quote marks as typographic quotes, instead of typewriter-style straight quotes. SC doesn’t understand the former but it does understand the latter.)

hjh

1 Like