musical.js

musical.js

musical.js: a tiny library with a sequencing WebAudio synthesizer that supports ABC notation.

Listen to a little demo here. musical.js can be used as a standalone script, a require.js AMD module, or as a node.js module. This code has no dependencies other than the HTML5 WebAudio API, and it minifies down to about 17K.

Originally designed as part of jQuery-turtle.

Three main functions in the API:

• instrument = new Instrument([timbre]) makes an instrument. Timbre is optional and defaults to a boring square wave sound. Timbre may be a WebAudio oscillator wave type ("square", "sine", "sawtooth", "triangle"), or a "piano" wave shape that is coded in this libarary. It may also specify (as object properties) gain (generally 0-1), attack (seconds for initial attack), decay (seconds for 1/e decay), sustain (amplitude of sustain), release (seconds for silence after release), cutoff (frequency of a lowapss filter), cutfollow (multiple of main frequency to add to lowpass cutoff), and detune (relative frequency of a second detuned oscillator); these allow basic subtractive analog synthesis. Timbre can be changed later using instrument.setTimbre. See an example below.

• instrument.tone(frequency [,volume, duration, delay, timbre]) plays a single tone for a little while. Frequency may be specified as a positive number (in Hz) or a negative integer (a midi note number), or a pitch string like '^C,' (ABC notation for a pitch). Other arguments are optional: volume defaults to 1, duration defaults to 10 seconds, delay defaults to zero (play right now), and timbre defaults to null, which applies the instrument's default timbre.

• instrument.play(abcnotation) plays a song as expressed in ABC notation, as can be found on the web. See examples below.

• There is also a silence() method and getTimbre() and setTimbre() for changing an instrument's sound. To listen to sequenced notes as they occur in realtime, listen to events with on('noteon', cb) and on('noteoff', cb). The instrument.off method unregisters a listener.

If used as a require.js or node module, then Instrument will be a member of the package. For example, after you do musical = require('musical'); then you can var ins = new musical.Instrument();.

<script src="musical.js"></script>

<script>

var inst = new Instrument();

// Play a single tone immediately.  Tones may be also specified
// numerically (in Hz), or with midi numbers (as negative integers).
inst.tone('C')

// Whenever we like, release the note.
setTimeout(function() {
  inst.tone('C', false);
  firstsong();
}, Math.random() * 10000);

function firstsong() {
  // Play "Mary Had a Little Lamb"
  inst.play({tempo:200},
      "AGFG|AAA2|GGG2|AAA2|AGFG|AAAA|GGAG|F4|z4", whendone)
}

// Do this after Mary is done.
function whendone() {
  // Play "Stairway", which picks out a few chords.
  inst.setTimbre({wave:'sawtooth', gain:0.15,
      attack:0.008, decay:0.2, release:0.2,
      cutoff:0, cutfollow:20, resonance:3});
  inst.play("F^Gcf|[gE]c^G|g[^g^D]c|^G^g[dD]|" +
             "^AFd|[^C=c]^GF|^G21/3c^GF|[G^DG,][F,F^G][^GFF,]2z4", whendone2);
}

// Do this after Stairway is done.
function whendone2() {
  // Change the inst to sound more like a piano.
  inst.setTimbre({wave:"piano"});
  // Then play a couple bars of a Beethoven Sonata, using ABC notation
  // clipped from the web.  Note support for chords, beats, accidentals,
  // key signatures, meter and tempo markings, ties, and so on.
  inst.play(
    "X:2\n" +
    "T:8th Sonata for inst\n" +
    "%%staves {1 2}\n" +
    "C:L. van Beethoven\n" +
    "M:C\n" +
    "L:1/16\n" +
    "Q:1/8=66\n" +
    "F:http://richardrobinson.tunebook.org.uk/tune/6525\n" +
    "K:Cm\n" +
    "V:1\n" +
    "!fp![E,4G,4C4]- [E,3/G,3/C3/]!3![G,/C/]!4![G,3/=B,3/D3/]!5![G,/C/E/] " +
    "([=A,4C4E4]!4![=B,2D2])z2|\\n" +
    "!fp!!3![=B,4D4F4]- [B,3/D3/F3/][B,/D/F/][B,3/D3/G3/][B,/D/A/] " +
    "([B,4D4A4]!3![C2E2G2])z2|\n" +
    "V:2\n" +
    "[C,,4E,,4G,,4C,4]- [C,,3/E,,3/G,,3/C,3/]!2!E,/!3!D,3/!4!C,/ " +
    "(!2!^F,4G,2)z _A,,|\\n" +
    "_A,4-A,3/!2!A,/!1!G,3/=F,/ E,4-E,2z2|\n"
  );
}
</script>

Building and testing musical.js

npm install
grunt