FOSSPicks

Oscilloscope music

osci-render

Despite a hardware user interface festooned with knobs and buttons, oscilloscopes perform a rather mundane function: They trace changes in input voltage over time. One input translates changes into movement along one axis while a second input translates changes onto the other axis. When the two input voltages are combined, the trace can move anywhere within the X and Y area of the screen. They're intended to visualize wave cycles within circuits, such as the voltages measured from a crystal oscillator or a microprocessor, and these could look like sine waves, or square pulses. Because they're also electrical signals, an audio signal through a wire is no different, and oscilloscopes are often used to visualize stereo audio signals. The output won't look good on screen, but you can see from this kind of trace whether the two inputs are in phase or compatible with mono speaker equipment.

Remarkably, there's a sub-genre of electronic music that generates an audio signal that both sounds interesting (musical may be a stretch too far) and looks amazing on an oscilloscope screen. The process starts with a series of complex transformations from X and Y coordinates into audio voltages that render as a pattern or image on the trace. Creating those transformations has always been difficult and has spawned commercial software for those interested in exploring the transformations further. And there hasn't been an open source option until now. Osci-render is a graphical application that can be used to transform a 3D model, text, an SVG file, or even a Lua script into a stereo audio signal that will regenerate the image on an oscilloscope. If you're into experimental electronic music, it can also sound amazing.

It sounds complicated, but it's easy to get started because the default project loads a 3D cube model by default. Connect your audio output to an oscilloscope, or use the web browser oscilloscope that can be loaded from the main application, and you can see this cube immediately. There are controls for rotating, zooming, and transforming the object, and these affect the sound that subsequently builds the image. The timbre of the audio depends on the complexity of the object, with simple objects more likely to create pleasing sine wave-like sounds and more complex objects generating lots of competing harmonics. A single triangle is an excellent source, for example, but you need to add object movement to animate the sound and the image.

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