Random note delay

[thomaskyhn]

I'm a complete newbie as regards JavaScript.

 

I found a basic note delay script, which I'd like to modify to get a random note delay script.

 

function HandleMIDI(event) {
event.send();
	if (event instanceof Note) {
		event.sendAfterMilliseconds(delayTime);
	}		
}

var delayTime;
var PluginParameters = [
{name:'Delay Time', type:'lin', unit:'ms',
minValue:0, maxValue:1200, defaultValue:1, numberOfSteps:120},
]

function ParameterChanged(param, value) {
var timeInMilliseconds = value;
if (param == 0) delayTime = timeInMilliseconds;	
};

 

I tried out this, but it's not working:

 

function HandleMIDI(event) {
event.send();
	if (event instanceof Note) {
		event.sendAfterMilliseconds(delayTime);
	}
}

var delayTime;
var PluginParameters = [
{name:'Random Delay', type:'lin', unit:'ms',
minValue:0, maxValue:12000, defaultValue:1, numberOfSteps:120},
]

function ParameterChanged(param, value) {
var delayTime = Math.random() * ((GetParameter("Random Delay")) * 10000);
};

 

Perhaps someone here would be able to point me in the right direction.

[Unheardofski]

You need a min value and a max value for Math.random.

 

example:

function delayTime(min,max) {
	return Math.floor(Math.random() * (max - min + 1)) + min;
}

 

Here's a fix:

 

 function HandleMIDI(event) {
	event.send();
	if (event instanceof Note) {
		event.sendAfterMilliseconds(randomDelay(0, delayTime));
	}
}

var delayTime = 0;
var PluginParameters = [{
	name: 'Random Delay',
	type: 'lin',
	unit: 'ms',
	minValue: 0,
	maxValue: 1200,
	defaultValue: 1,
	numberOfSteps: 120
}, ]

	function ParameterChanged(param, value) {
		delayTime = value;
	};

function randomDelay(min, max) {
	return Math.floor(Math.random() * (max - min + 1)) + min;
}

[thomaskyhn]

Thanks for your help!

 

If I wanted to leave out the initial note and only have the delay, what part would I need to change? As I understand, the second line – "event.send();" – lets the initial note pass through untouched, but just deleting that part doesn't seem to work.

[Eric Cardenas]

Use:

event.trace();

[thomaskyhn]

Replacing

event.send();

with

eventTrace();

gives me this output:

 

Exception calling HandleMIDI() function:

[JS Exception] TypeError: event.Trace is not a function. (In 'event.Trace()', 'event.Trace' is undefined) line:2

 

Do I need to put it somewhere else?

[Eric Cardenas]

Sorry...

 

I edited my post it's:

 

   event.trace();

[Unheardofski]

Actually you should keep track of the generated delay and assign it to the note off as well. Otherwise you can end up sending note off before note on.

[thomaskyhn]

Sorry...

 

I edited my post it's:

 

   event.trace();

Thanks! It works now.

[thomaskyhn]

Actually you should keep track of the generated delay and assign it to the note off as well. Otherwise you can end up sending note off before note on.

That makes sense.

[Eric Cardenas]

Actually you should keep track of the generated delay and assign it to the note off as well. Otherwise you can end up sending note off before note on.

 

Thanks Unheardofski.

How do you do that exactly. I've wondered about this myself?

[thomaskyhn]

I tried this, but it doesn't work as intended:

 

 function HandleMIDI(event) {
event.trace();
   if (event instanceof NoteOn) {
      event.sendAfterMilliseconds(randomDelay(0, delayTime));
   }
   else if (event instanceof NoteOff ) {
      event.sendAfterMilliseconds(randomDelay(0, delayTime));
   }  
}

 

I assume that rather than apply the same random delay to both events, it randomizes them individually.

[Unheardofski]

a bit swamped can't explain right now, this is how I'd do the whole thing from scratch - but there is no ONE correct way

 

 

var PluginParameters = [];
var noteDelay = [];
for (var i = 0; i < 128; i++) {
noteDelay[i] = 0;
}
var keep = 0;
var maxDelay = 0;

createParam('Random delay max ms', 'lin', 0, 0, 1200, 0, 1200, 'ms');
createParam('Keep original note? ', 'menu', ['Off', 'On '],0,1,0);

function ParameterChanged(p,v){
p ? keep = v : maxDelay = v;
}
function HandleMIDI(e){
if(e instanceof Note){
e instanceof NoteOn ? e.delay = randomDelay(0, maxDelay):e.delay = noteDelay[e.pitch];
e instanceof NoteOn ? noteDelay[e.pitch] = e.delay:false;
keep ? e.send():false;
e.sendAfterMilliseconds([e.delay]);
}
else
e.send();
}

function createParam(n, t, vs, miv, mav, def, nos, unit) {
	PluginParameters.push({
		name: n,
		type: t,
		valueStrings: vs,
		minValue: miv,
		maxValue: mav,
		defaultValue: def,
		numberOfSteps: nos,
		unit: unit
	});
}
function randomDelay(min, max) {
	return Math.floor(Math.random() * (max - min + 1)) + min;
}

[Eric Cardenas]

Thank you so much!

[thomaskyhn]

Thanks!!

[Unheardofski]

You'r welcome guys. Here are some comments to help grasp the script

 

We declare our global variables here, noteDelay is an Array which we also initialise by looping with one 'spot' for each midi note. We also add a variable for the option of keeping the original note or not:

var PluginParameters = [];
var noteDelay = [];
for (var i = 0; i < 128; i++) {
  noteDelay[i] = 0;
}
var keep = 0;
var maxDelay = 0;

 

I've made this simple function instead of having to type out each 'Param push' - function itself is closer to the bottom of the script:

createParam('Random delay max ms', 'lin', 0, 0, 1200, 0, 1200, 'ms');
createParam('Keep original note? ', 'menu', ['Off', 'On '],0,1,0);

 

Since we only have two parameters we can use a ternary operator to save space and not have to type a novel. This basically means in plain speak. "p (param) exists? (1 will return true, 0 returns false - so if the function receives parameter 1 this is true, if parameter 0 its false) if yes keep equals the value, if no maxDelay equals the value.

function ParameterChanged(p,v){
p ? keep = v : maxDelay = v;
}

 

We use a standard if operator to separate note events from non-note events.

Then I went with ternary again - note how you can use false if you only want to use it for one outcome.

So we first check if its note on or off. If on we get the delay from the random delay function***. If off we get it from the array (note ons send it to the array in the next line) by getting the element that corresponds to the note pitch.

***Here's the neat part; even though a MIDI event normally doesn't have a delay property, we can create it by simply declaring it.

Then if we have a note on we store the delay value in the noteDelay array.

Next we check the keep variable, if its 1 we send the note unchanged.

Finally we send our delayed note regardless if note on or off.

The function ends with sending any non note event.

function HandleMIDI(e){
if(e instanceof Note){
e instanceof NoteOn ? e.delay = randomDelay(0, maxDelay):e.delay = noteDelay[e.pitch];
e instanceof NoteOn ? noteDelay[e.pitch] = e.delay:false;
keep ? e.send():false;
//e.sendAfterMilliseconds([e.delay]); //Noticed this looks weird. Should probably be:
e.sendAfterMilliseconds(e.delay);
}
else
e.send();
}

This is a good link to understand the Math functions: http://www.w3schools.com/jsref/jsref_obj_math.asp

function randomDelay(min, max) {
   return Math.floor(Math.random() * (max - min + 1)) + min;
}

[thomaskyhn]

Is there a simple way to modify this script in order to get a random note length effect?

[Unheardofski]

made some small additions to achieve this.

 

var PluginParameters = [];
var noteDelay = [];
for (var i = 0; i < 128; i++) {
  noteDelay[i] = 0;
}
var keep = 0;
var maxDelay = 0;
var min_len = 0;
var max_len = 0;

createParam('Random delay max ms', 'lin', 0, 0, 1200, 0, 1200, 'ms');
createParam('Min note length ms', 'lin', 0, 0, 1200, 0, 1200, 'ms');
createParam('Max note length ms', 'lin', 0, 0, 1200, 0, 1200, 'ms');
createParam('Keep original note? ', 'menu', ['Off', 'On '],0,1,0);

function ParameterChanged(p,v){
p == 0 ? maxDelay = v :false;
p == 1 ? min_len = v: false;
p == 2 ? max_len = v : false;
p == 3 ? keep = v : false;
}
function HandleMIDI(e){
if(e instanceof Note){
e instanceof NoteOn ? e.delay = randomDelay(0, maxDelay):e.delay = noteDelay[e.pitch] + randomDelay(min_len,max_len);
e instanceof NoteOn ? noteDelay[e.pitch] = e.delay:false;
keep ? e.send():false;
e.sendAfterMilliseconds(e.delay);
}
else
e.send();
}

  function createParam(n, t, vs, miv, mav, def, nos, unit) {
     PluginParameters.push({
        name: n,
        type: t,
        valueStrings: vs,
        minValue: miv,
        maxValue: mav,
        defaultValue: def,
        numberOfSteps: nos,
        unit: unit
     });
  }
function randomDelay(min, max) {
   return Math.floor(Math.random() * (max - min + 1)) + min;
}

[thomaskyhn]

made some small additions to achieve this.

Thanks so much!