Consider for a moment the following small fragment of C code, which outputs a sequence of bytes based on an ever-incrementing counter ( t ):

for ( t = 0 ;; t ++ ) { putchar ( t * (( t >> 12 | t >> 8 ) & 63 & t >> 4 )); }

Now imagine this is generating samples to be passed to a DAC to create sound (e.g. pipe the output of this program to /dev/dsp on a Unix system). What do you think this would sound like? Probably just a bunch of random crunchy noise, right? The formula, a seemingly arbitrary combination of mostly bitwise operators, doesn’t really resemble a typical synthesis algorithm. There are no obviously periodic aspects to the formula; there are no sine or cosine functions.

And yet if you actually try running this, you’ll see that it produces a musical, chiptune-style melody that exhibits a surprising amount of variety, both in terms of its melody and timbre, as it evolves over time. This formula and many others were originally discovered in the demoscene community, principally by Viznut, and documented in a series of blog posts and YouTube videos; the first one is worth checking out if you haven’t seen this already:

This phenomena has come to be known as byte beats, and people have been exploring the musical possibilities of these short formulas through a variety of applications (Bitwiz and GlitchMachine for iOS are some of my favourites). You can try some out on the web here.

Personally, I am fascinated by two aspects of these formulas:

You can pack an enormous amount of sonic variety in an extremely concise formula; byte beats are generative in the best sense.

The synthesis technique is somewhat mysterious, and mixes concerns about melody and timbre.

If you are curious about why these formulas sound the way they do, Viznut has a fairly in-depth analysis of some of them in this blog post. To simplify, the periodicity that is required for harmonic sounds comes from the implicit modular “wrap-around” that occurs when you 8-bit downsample the evaluated value of a formula. The melodies come from the bitshift operators, which are tantamount to multiplication or division by powers of two, and thus create the kinds of whole-number interval relations between frequencies that exist in melodies.

I’m not particularly interested in engineering byte beat formulas to make conventional sounds or melodies, although I can see how this would be a really cool “compression algorithm” for the soundtrack to a 64kB demo. For me, the fun is in playing around with these formulas in a trial-and-error kind of way, and just seeing what kind of sounds you can produce.

For the past few months, I’ve been working on a browser-based program for exploring the sonic possibilities of byte beats in a fun and intuitive way. The idea is to use genetic programming to generate novel and interesting byte beat formulas. I’m coding the project using ClojureScript and rendering the audio in-browser using the Web Audio API. I’ll be documenting my work on this project in a series of upcoming posts.