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Tilt

Bytebeat-inspired live coding thingie for waveshaping synthesis.

Runs on modern browsers using the WebAudio API.

Tutorial

Check out the tutorial if you want to learn how to use Tilt while also learning a little bit about sound synthesis :-)

Usage

To make some audio, define the value of the variable o. It must be a number between 0 and 1. For this, you can use the t parameter, which is an always-increasing counter.

For example, to make a sine wave at 440hz:

o = sine(t);

Evaluate code by pressing the Play button, or Ctrl+Enter (or Command+Enter). You can stop sound by pressing the Stop button, or Ctrl+..

You can make all sorts of simple (and more complex) waveforms:

// saw wave
let q = 2 * pi;
o = (t % q) / q;
// square wave
let q = 2 * pi;
o = (t % q) / q > 0.5;
// pulse wave with pulse-width modulation
let q = 2 * pi;
o = (t % q) / q > seq(256, 64) / 64;
// triangle wave
let ramp = (t % q) / q;
o = ((ramp > 0.5 ? ramp : 1 - ramp) - 0.5) * 2;

These simple waveforms are also already defined as functions. Read below.

There is also a parameter K which is static and represents the number of samples in a cycle. It is used to make rhythm. See the function seq or randInt, as they use it internally.

A more complex example, using some of the functions described below:

o = sine(t / (randInt(8, 32) + 1)) * env(8, 1) * 0.75;
o +=
  sine((t * aseq(16, [2, 3, 2, 7, 8])) / 4 + sine((t / aseq(8, [1, 2])) * 1.0001)) *
  invEnv(seq1(32, 8), seq1(4, 8) + 1) *
  0.75;

Remember that o should be a number between 0 and 1. If you add multiple waveforms, you should scale them down to mix them properly. For example, instead of:

o = sine(t) + tri(t);

You should do something like this:

o = sine(t) * 0.5 + tri(t) * 0.5;

Why 0.5? Because both sine(t) and tri(t) output values from 0 to 1. If you multiply them with 0.5 (or divide them by 2), they should range between 0 and 0.5, which when both are added up, they end up ranging from 0 to 1.

Functions

Code is written in JavaScript, but there are some useful constants and functions available.

Math

Most of the functions from Math object in JavaScript are defined as globals, but the following are the most useful:

  • pi: Pi constant.
  • two_pi: 2 times Pi
  • abs(arg): Returns the absolute value of a number.
  • sin(arg): Returns the sine of a number.
  • tan(arg): Returns the tangent value of a number.
  • tanh(arg): Returns the hyperbolic tangent value of a number.
  • floor(arg): Returns the largest integer less than or equal to a given number.
  • ceil(arg): Returns the smallest integer greater than or equal to a given number.
  • pow(arg): Returns base to the exponent power.
  • round(arg): Returns the value of a number rounded to the nearest integer.
  • sqrt(arg): Returns the positive square root of a number.

Note: sin returns a number from -1 to 1, there is also sine which returns a number from 0 to 1, suitable as audio output.

Waveforms

These functions all return numbers from 0 to 1, so they can be used directly as audio output.

  • sine(t): Sine waveform
  • saw(t): Saw waveform
  • pulse(t, width): Pulse waveform
  • square(t): Square waveform (same as Pulse with width 0.5)
  • tri(t): Triangle waveform

Sequences

  • seq(subdiv, subdiv): Returns a number from 0 to length - 1 in subdiv subdivisions of a cycle (defined by K).
  • seq1(subdiv, length): Same as seq, but number range from 1 to length. subdivisions of a cycle (defined by K).
  • aseq(subdiv, array): Returns values from array in subdiv subdivisions of a cycle. Basically, sequences an array.

Envelopes

  • env(subdiv, curve, smooth): Generates an exponential envelope that lasts subdiv subdivisions of a cycle, with an exponent curve. The optional smooth argument is a 0-1 number that splits the envelope into an increasing linear ramp for a smoother attack (0=no smoothing, 1=linear ramp).
  • invEnv(subdiv, curve, smooth): Same as env but generates an inverse exponential envelope. The smooth argument controls a decreasing ramp at the end of the envelope.

Random

  • rand(subdiv, seed): Returns a random number between 0 and 1. The number is held during subdiv subdivisions of a cycle. When using the same seed you can generate the same sequence of random numbers.
  • randInt(subdiv, max, seed): Same as rand but generates a integer numbers from 0 to max.

Time

These functions generally replace the use of the t counter variable for musically-related concepts:

  • f(frequency): Generates a counter at the specified frequency (e.g. sine(f(440)) == sine(t)).
  • m(midinote): Generates a counter at the specified MIDI note (e.g. sine(m(69)) == sine(t), because 69 is the A4, which is 440Hz).

License

GPL 3+. Refer to LICENSE.txt

Icons:

  • Play by Eagle Eye from the Noun Project
  • Stop by vectoriconset10 from the Noun Project