Eli Silverstein

project Technology Audio DSP

Audio DSP

Making custom audio effects

Convolution

A big word that means delaying and multiplying an input waveform by some other function, which creates all sorts of audio effects. The image is that “other function,” called a kernel: the kernel for a sinc function, a type of frequency filter that (theoretically) perfectly low-passes a signal without changing the phase of any of the input frequencies.

Sinc kernel

Output

I took the kernel above and multiplied it with an input square wave on a microcontroller. I like pushing microcontrollers to the limits of what they are capable of >:)

Convolution output

Digital sampling

Sampling a sine wave at a very high frequency. It's neat and shows how the microcontrollers I use process the audio samples.

Sampled sine

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