ZzFX.js

/*

ZzFX - Zuper Zmall Zound Zynth v1.1.8
By Frank Force 2019
https://github.com/KilledByAPixel/ZzFX

ZzFX Features

- Tiny synth engine with 20 controllable parameters.
- Play sounds via code, no need for sound assed files!
- Compatible with most modern web browsers.
- Small code footprint, the micro version is under 1 kilobyte.
- Can produce a huge variety of sound effect types.
- Sounds can be played with a short call. zzfx(...[,,,,.1,,,,9])
- A small bit of randomness appied to sounds when played.
- Use ZZFX.GetNote to get frequencies on a standard diatonic scale.
- Sounds can be saved out as wav files for offline playback.
- No additional libraries or dependencies are required.

*/
/*

  ZzFX MIT License
  
  Copyright (c) 2019 - Frank Force
  
  Permission is hereby granted, free of charge, to any person obtaining a copy
  of this software and associated documentation files (the "Software"), to deal
  in the Software without restriction, including without limitation the rights
  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  copies of the Software, and to permit persons to whom the Software is
  furnished to do so, subject to the following conditions:
  
  The above copyright notice and this permission notice shall be included in all
  copies or substantial portions of the Software.
  
  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  SOFTWARE.
  
*/

'use strict';

// play a zzfx sound
export function zzfx(...parameters) { return ZZFX.play(...parameters) }

// zzfx object with some extra functionalty
export const ZZFX =
{
    // master volume scale
    volume: .3,
    
    // sample rate for audio
    sampleRate: 44100,
    
    // create shared audio context
    x: new (window.AudioContext || webkitAudioContext),

    // play a sound from zzfx paramerters
    play: function(...parameters)
    {
        // build samples and start sound
        return this.playSamples(this.buildSamples(...parameters));
    },

    // play an array of samples
    playSamples: function(...samples)
    {
        // create buffer and source
        const buffer = this.x.createBuffer(samples.length, samples[0].length, this.sampleRate),
            source = this.x.createBufferSource();

        samples.map((d,i)=> buffer.getChannelData(i).set(d));
        source.buffer = buffer;
        source.connect(this.x.destination);
        source.start();
        return source;
    },

    // build an array of samples
    buildSamples: function
    (
        volume = 1, 
        randomness = .05,
        frequency = 220,
        attack = 0,
        sustain = 0,
        release = .1,
        shape = 0,
        shapeCurve = 1,
        slide = 0, 
        deltaSlide = 0, 
        pitchJump = 0, 
        pitchJumpTime = 0, 
        repeatTime = 0, 
        noise = 0,
        modulation = 0,
        bitCrush = 0,
        delay = 0,
        sustainVolume = 1,
        decay = 0,
        tremolo = 0
    )
    {
        // init parameters
        const PI2 = Math.PI*2;
        let sampleRate = this.sampleRate,
        sign = v => v>0?1:-1,
        startSlide = slide *= 500 * PI2 / sampleRate / sampleRate,
        startFrequency = frequency *= 
            (1 + randomness*2*Math.random() - randomness) * PI2 / sampleRate,
        b=[], t=0, tm=0, i=0, j=1, r=0, c=0, s=0, f, length;

        // scale by sample rate
        attack = attack * sampleRate + 9; // minimum attack to prevent pop
        decay *= sampleRate;
        sustain *= sampleRate;
        release *= sampleRate;
        delay *= sampleRate;
        deltaSlide *= 500 * PI2 / sampleRate**3;
        modulation *= PI2 / sampleRate;
        pitchJump *= PI2 / sampleRate;
        pitchJumpTime *= sampleRate;
        repeatTime = repeatTime * sampleRate | 0;

        // generate waveform
        for(length = attack + decay + sustain + release + delay | 0;
            i < length; b[i++] = s)
        {
            if (!(++c%(bitCrush*100|0)))                      // bit crush
            { 
                s = shape? shape>1? shape>2? shape>3?         // wave shape
                    Math.sin((t%PI2)**3) :                    // 4 noise
                    Math.max(Math.min(Math.tan(t),1),-1):     // 3 tan
                    1-(2*t/PI2%2+2)%2:                        // 2 saw
                    1-4*Math.abs(Math.round(t/PI2)-t/PI2):    // 1 triangle
                    Math.sin(t);                              // 0 sin

                s = (repeatTime ?
                        1 - tremolo + tremolo*Math.sin(PI2*i/repeatTime) // tremolo
                        : 1) *
                    sign(s)*(Math.abs(s)**shapeCurve) *       // curve 0=square, 2=pointy
                    volume * this.volume * (                  // envelope
                    i < attack ? i/attack :                   // attack
                    i < attack + decay ?                      // decay
                    1-((i-attack)/decay)*(1-sustainVolume) :  // decay falloff
                    i < attack  + decay + sustain ?           // sustain
                    sustainVolume :                           // sustain volume
                    i < length - delay ?                      // release
                    (length - i - delay)/release *            // release falloff
                    sustainVolume :                           // release volume
                    0);                                       // post release

                s = delay ? s/2 + (delay > i ? 0 :            // delay
                    (i<length-delay? 1 : (length-i)/delay) *  // release delay 
                    b[i-delay|0]/2) : s;                      // sample delay
            }

            f = (frequency += slide += deltaSlide) *          // frequency
                Math.cos(modulation*tm++);                    // modulation
            t += f - f*noise*(1 - (Math.sin(i)+1)*1e9%2);     // noise

            if (j && ++j > pitchJumpTime)       // pitch jump
            {
                frequency += pitchJump;         // apply pitch jump
                startFrequency += pitchJump;    // also apply to start
                j = 0;                          // stop pitch jump time
            }

            if (repeatTime && !(++r % repeatTime)) // repeat
            {
                frequency = startFrequency;     // reset frequency
                slide = startSlide;             // reset slide
                j = j || 1;                     // reset pitch jump time
            }
        }

        return b;
    },
    
    // get frequency of a musical note on a diatonic scale
    getNote: function(semitoneOffset=0, rootNoteFrequency=440)
    {
        return rootNoteFrequency * 2**(semitoneOffset/12);
    }

} // ZZFX