Wigout

Wigout is a program for time-domain synthesis. In frequency-domain synthesis, the composer specifies the frequency and amplitudes she wants, and gets that result. In time-domain synthesis, one specifies the structure of a waveform, and how it changes over time. The constructed waveform then, creates the frequency and amplitude changes.

Wigout defines a waveform as sequence of segments:

In this slide, there are three segments, and that sequence is iterated 3 times. This sequence has a duration of about 7 thousandths of a second.

Each segment has two variables: a duration (measured in samples) and an amplitude (between $\pm 32767$). In this example, on each iteration the segments' amplitude and duration remain the same.

If both amplitude and duration were changing, the three iterations might look like this:

This is the fundamental idea of wigout: on each iteration, every segment changes it amplitude and its duration by a specified increment. When either variable reaches its minium or maximum limit (which can be specified), that variable reverses its direction of change: If it was increasing, it starts decreasing; if decreasing, it starts increasing.

After 10 iterations (about 1/10 of a second), the waveform looks like this:

After 100 iterations (about 6/10 of a second), it looks like this:

Here's what 10 seconds of this transformation sound like:

Sound example 1: 10 seconds

And here's a plot of how the frequencies are changing during the first second. The other slides I showed you were slides of the waveform. This is a slide of the frequency changes.

The duration of a segment determines its frequency. If I reduce the duration increment, I slow down the frequency's rate of change.

The frequency plot then looks like this:

And it sounds like this:

Sound example 2: 10 seconds

If, in addition to reducing the duration increment, I also reduce down the amplitude increment, the result sounds like this:

Sound example 3: 10 seconds

The changes in amplitude are now a kind of intermittent vibrato.

Reducing the amplitude increment even further sounds like this:

Sound example 4: 10 seconds