Author Archives: Nigel Redmon

How I write code

Next article I’ll post an update of our wave table oscillator, but first I’ll take the opportunity to discuss how I write code these days. Maybe it will help make sense of some of the choices in the code I … Continue reading

Posted in Source Code | 18 Comments

Floating point denormals

There’s another issue with floating point hardware that can easily cause serious performance problems in DSP code. Fortunately, it’s also easy to guard against if you understand the issue. I covered this topic a few years ago in A note … Continue reading

Posted in Math | 6 Comments

Floating point caveats

The equivalent of “When I was your age, we use to walk to school in the snow. Barefoot”, in DSP, is to say we used to do DSP in fixed point math. The fixed-point system could be made of integer … Continue reading

Posted in Math | 9 Comments

Wavetable signal to noise ratio

In our wavetable series, we discussed what size our wavetables needed to be in order to give us an appropriate number of harmonics. But since we interpolated between adjacent table entries, the table size also dictates the signal to noise … Continue reading

Posted in Digital Audio, Oscillators, Wavetable Oscillators | Leave a comment

Sampling theory, the best explanation you’ve ever heard—End notes

A few words before moving on to other topics… We’ve looked at why digital sample represent ideal impulses, and why any point between samples represents a value of zero. And, as a result, audio samples don’t represent the audio itself, … Continue reading

Posted in Digital Audio, Sampling Theory | Tagged | 2 Comments

Sampling theory, the best explanation you’ve ever heard—Part 3

We look at what Pulse Amplitude Modulation added to our analog source audio. What did PAM add? Earlier, we noted that the PAM signal represents the the source signal plus some additional high frequency content that we need to remove … Continue reading

Posted in Digital Audio, Sampling Theory | Tagged | 5 Comments

Sampling theory, the best explanation you’ve ever heard—Part 2

In this article, we explore the origins of sampling. Discrete time For many, discrete time and digital sampling are synonymous, because most people have little experience with discrete time analog. But perhaps you’ve used an old-style analog delay stompbox, with … Continue reading

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Sampling theory, the best explanation you’ve ever heard—Part 1

I’ll start by giving away secrets first: Individual digital samples are impulses. Not bandlimited impulses, ideal ones. We know what lies between samples—virtual zero samples. Audio samples don’t represent the source audio. They represent a modulated version of the audio. … Continue reading

Posted in Digital Audio, Sampling Theory | Tagged | 4 Comments

Sampling theory, the best explanation you’ve ever heard—Prologue

I’ve been working on a new video, with the goal of giving the best explanation of digital sampling you’ve ever heard. The catch is I started on it three years ago. I’m not that slow, it’s just that I’ve been … Continue reading

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Amp simulation oversampling

In tandem with our last article on Guitar amp simulation, this article gives a step by step view of the sampling and rate conversion processes, with a look at the frequency spectrum. From guitar to digital The first two charts embody the … Continue reading

Posted in Digital Audio, Effects, Guitar Amp Simulation, Sample Rate Conversion | 4 Comments