Oscillixir

An attempt at making an audio synthesizer in Elixir.

Components

Time Source

The Source.Timer module provides a time source for audio signal. It periodically notifies the Sequence.Range which creates a series of time values.

By default:

* The Source.Timer generates an event notification every 10 ms.
* The Sequence.Range generates 441 time events with interval of 0.000022675736961451248.

The result is a sequence of time events representing 44100 Hz.

Oscillators

An Oscillator is notified with a time, and creates a signal event. The supported oscillators are:

* Square
* Saw
* Triangle
* Sine

Background Research and Design Choices

For CD-quality audio:

• the sample rate is 44,100 samples per second.
• has a sample size of 16 bits
• has 2 channels

The common range of human hearing is 20 Hz to 20 kHz. Humans can hear as low as 12 Hz.

1/44100 second/samples = 0.000022675736961451248 second/sample ~= 23 microsecond/sample

(0.001 second) / (0.000023 second/sample) = 43.47826086956522 samples ~= 43 samples

The Erlang timer is only accurate to 1 millisecond. Erlang rem function only works on integers. :math.sin/1 is the Erlang sine function

The base time unit will be 1 microsecond. This allows many of the calculations to be performed as integers.

Installation

If available in Hex, the package can be installed as:

1. Add oscillixir to your list of dependencies in mix.exs:

   def deps do [{:oscillixir, "~> 0.0.1"}] end

2. Ensure oscillixir is started before your application:

   def application do [applications: [:oscillixir]] end