stuttering / noise when using amp(float volume) continously

[trackme518]

Hi,
I am getting noticeable glitches / noise when using amp(float volume) continuously. Example with custom Envelope function - code below. Tested on Linux Mint.

import processing.sound.*;
AmpplitudeEnvelope env;
Track track;

void setup(){
 frameRate(1000);
 JSONObject json = new JSONObject();
 json.setFloat("attack", 0.8);
 json.setFloat("sustain", 0.9);
 json.setFloat("release", 1.2);
 json.setFloat("level", 0.8);

 track = new Track( new SoundFile(this, "zvonkohra.wav") );
 track.sample.loop();

 env = new AmpplitudeEnvelope(json);
}

void draw(){
 env.update();
}

void mousePressed(){
 env.reset();
}


class Track{
 SoundFile sample;
 Track(SoundFile fil){
 sample = fil;
 }
}
//custom envelopes class - i want to operate on existing samples + let them play
class AmpplitudeEnvelope{
 float attack; //in seconds
 float sustain;
 float release;
 float level;//between 0-1
 Track audiotrack = null; //reference to existing track with SoundFile object
 long started = 0;//when we start attack
 int state = 0;//0=attack,1=sustain,2=release,3=ended
 float amplitude = 0.0;

 AmpplitudeEnvelope(JSONObject json){
 this.attack = json.getFloat("attack");
 this.sustain = json.getFloat("sustain");
 this.release = json.getFloat("release");
 this.level = json.getFloat("level");
 this.audiotrack = track;

 }

 void reset(){
 started = millis();
 amplitude = 0.0; //start silent
 println("envelope triggered");
 }

 void update(){

 float delta = (millis()-started)/1000.0;
 //println(delta);
 if ( delta<attack){//attack
 state = 0;
 amplitude = map( delta, 0, attack, 0, level);//where we are at current curve for volume change
 } else if ( delta>attack && delta<attack+sustain){//sustain
 state = 1;
 amplitude = level;
 } else if ( delta>attack+sustain && delta<attack+sustain+release ){//release
 state = 2;
 amplitude = map( (delta-attack-sustain), 0, release, level, 0);//where we are at current curve for volume change
 } else if ( delta>attack+sustain+release ){
 state = 3; //finished
 amplitude = 0.0;
 }
 //----
 if (this.audiotrack!=null){
 if ( this.audiotrack.sample != null){
 this.audiotrack.sample.amp(amplitude);
 //println(this.amplitude);
 }
 }
 //----
 }
}

[kevinstadler]

I wonder if this is issue is specific to Linux Mint? I just tried your sketch on MacOS and it sounds perfectly fine. I think it should also be possible to call the built-in Env envelope functionality on a looping SoundFile, I wonder if that would make a difference for performance/stuttering.