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Category Archives: Aliasing
Guitar amp simulation
In this article, I’ll sketch a basic guitar amp simulator. For one, questions on the topic come up often, and also, it will be a good example of a typical use of working at a higher sample rate. The most … Continue reading
Posted in Aliasing, Digital Audio, Sample Rate Conversion
3 Comments
Wavetable oscillator video
If you find this video helpful, let me know, and I’ll work more video demonstrations into articles.
Posted in Aliasing, Synthesizers, Video, Wavetable Oscillators
6 Comments
A wavetable oscillator—Part 2
From Part 1, we have an oscillator. But we need to broaden it to allow scaling of harmonic content based on pitch so that we have all the harmonic content we need at the low frequency end, and, as we … Continue reading
Posted in Aliasing, Digital Audio, Oscillators, Wavetable Oscillators
25 Comments
Sample rate conversion: down
In doubling the sample rate, we inserted zeros between existing samples, then used a lowpass filter to remove the resulting alias in the audio band. To resample at half the current rate, we use a lowpass filter to remove audio … Continue reading
Posted in Aliasing, Digital Audio, Filters, Sample Rate Conversion
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Sample rate conversion: up
Once we have a suitable set of FIR filter coefficients from our windowed sinc calculator, it’s time to apply them. Again, our recipe for doubling the sample rate: 1) Insert a zero between existing samples. (This is the upsampling step, … Continue reading
Posted in Aliasing, Convolution, Digital Audio, Filters, FIR Filters, Sample Rate Conversion
7 Comments
What is aliasing?
It’s easiest to describe aliasing in terms of a visual sampling system we all know and love—movies. If you’ve ever watched a western and seen the wheel of a rolling wagon appear to be going backwards, you’ve witnessed aliasing. The … Continue reading
Posted in Aliasing, Digital Audio
16 Comments
Oversampling
In this discussion, “oversampling” means oversampling on output—at the digital to analog conversion stage. There is also a technique for oversampling at the input (analog to digital) stage, but it is not nearly as interesting, and in fact is unrelated … Continue reading
Posted in Aliasing, Digital Audio, Sample Rate Conversion
4 Comments
Digital audio: theory and reality
The promise of perfect audio—the Nyquist Theorem Most people who’ve look at digital audio before know about the Nyquist theorem—if you sample an analog signal at a rate of at least twice its highest frequency component, you can convert it … Continue reading
Posted in Aliasing, Digital Audio, Dither, Jitter, Phase
12 Comments