semi-random music generator

Android Processing

rsylv

in Android Processing • 1 year ago

Hi,

I'm attempting to write a semi-random auto-play music generator for Android based on the below code which is causing some unpredictable timing. I'm wondering if there's a more efficient/clever way to do this?

void zTrigger() {
float r = random(40);
if (r >= 0 && r <= 4) {
chord1();
}
if (r >= 5 && r <= 7) {
chord2();
}
if (r >= 8 && r <= 10) {
chord 3();
}
if (r >= 11 && r <= 14) {
chord4();
}
if (r >= 15 && r <= 18) {
chord5();
}
if (r >= 19 && r <= 22) {
chord6();
}
if (r >= 23 && r <= 24) {
chord7();
}
}

The chord functions are being triggered by the following code in draw which ads a simple beat. The beat plays reasonably in time on it's own but when I add the zTrigger function I get some unintended skipping in timing every 5-10secs.

if (zMode) {
fill(200,0,0);
ellipse(60,190,20,20);
//8th Note Beat
if (millis() - sTime3 >= (tempoTime/2)) {
percussion3();
sTime3 = millis();
//1/4 note beat
if (millis() - sTime >= (tempoTime)) {
percussion1();
zTrigger();
sTime = millis();
}
}
}

Replies(3)

PhiLho

Re: semi-random music generator

1 year ago

void zTrigger() {
float r = random(40);
if (r < 4) {
chord1();
} else if (r < 7) {
chord2();
} else if (r < 10) {
chord 3();
} else {
// etc.
} else if (r < 24) {
chord7();
}
}

You were leaving holes in the tests (since r is a float, it can be between 4 and 5, for example), and although it is probably imperceptible in time, there is no need to check for the next ranges once one is found.
You don't manage r above 24, too, not sure if that's intended.

rsylv

Re: semi-random music generator

1 year ago

Of course! Forgot I was dealing with a float there. I was purposely not handling r above 24 to leave space where a chord isn't played occasionally.

This explains a few things and it's working better now, although the timing does still falter a little, as if millis() is reading a little inconsistently or maybe there's some background process going on I need to look into.

thanks again.

PhiLho

Re: semi-random music generator

1 year ago

Yes, Java isn't real time, and multi-process systems doesn't ease real time generation.
Moreover, Processing probably calls your code only 60 times per seconds (by default), so indeed you can miss some ms in the process. You can try and increase the frame rate to see if there is an improvement.

Honestly, my improvement is on the readability / reduced (typing) work side, not on the time efficiency one. And well, also if not missing the intervals is important, on such side too...