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Zgrzytor
Simple pseudorandom waveform generator using shift register with EXOR feedback
Grzegorz Kraszewski

Zgrzytor has been written as an example of using Reggae audio savers without a GUI. It generates a pseudonoise audio wave using shifting register with EXOR feedback. Location of EXOR taps is adjustable, so many different noises may be generated. The wave may be saved in any audio format supported by Reggae. Zgrzytor provides high quality 32-bit sound. Duration of sound is always 5 seconds.

Usage

Zgrzytor has no GUI so it is fully controlled via commandline arguments. Its DOS argument template is:

TAP1/N/A,TAP2/N/A,SAMPLERATE/N/A,OUTPUT/A,FORMAT/F

where

Examples

Zgrzytor 2 19 44100 RAM:zgrzyt.wav WAVE

Generates some noise sampled at 44.1 kHz, saves it to a 16-bit (default for WAVE codec) WAVE file.

Zgrzytor 2 20 44100 RAM:zgrzyt.aiff AIFF BITS=24

More periodic noise (a bit like some engine working), saved as 24-bit AIFF.

Zgrzytor 2 23 44100 RAM:zgrzyt.raw RAWAUDIO BITS=24 LE

This time almost continuous white noise is saved as raw 24-bit samples with little endian byte ordering. Note that in case of raw samples, sampling rate is irrelevant.

Audio Samples

As each of taps can be placed on bit 1 to 32, zgrzytor is able to produce 496 different noises (not 1024, as putting both the taps on the same bit always gives silence, also EXOR gate is symmetrical, so order of taps makes no difference). But it is not all. The shift register is initialized to a random contents from a good enthropy source. For short period noises it gives different timbre while maintaining pitch. For longer ones the wave period is shifted. For the longest ones a different fragment of period is generated. Below there are some examples of noises to listen, generated as 16-bit WAVEs @ 44.1 kHz:

Of course as these sounds are purely algorithmically generated with a common knowledge algorithm, I consider these files the public domain. Feel free to use them as you like.

Download

Zgrzytor 1.1 (25 kB) for MorphOS 3.0+, on MorphOS Files. The source code is included inside the archive.

History

Version 1.1 (2013-05-05) added full 32-bit sound quality.

Version 1.0 (2012-04-10) was the first release.

Last updated: 2013-05-05.