4 ms·

>aliasing sounds a lot worse than analog imperfections The Commodore Amiga has the crudest possible anti-aliasing filter: a single fixed-frequency low-pass fil

by mrob 6y ago

>aliasing sounds a lot worse than analog imperfections The Commodore Amiga has the crudest possible anti-aliasing filter: a single fixed-frequency low-pass filter shared by all 4 channels. It does not work very well, so aliasing is a defining characteristic of the Amiga sound. Aliasing adds high frequency content that compensates for the low sample rates required by memory limitations, and extra harmonic complexity that compensates for the low channel count. I think Amiga modules sound worse if played by something with good anti-aliasing filters.

nyanpasu64 6y ago
In my (pedantic) understanding, the Amiga doesn't suffer from aliasing, because it uses a period register used to divide a very high frequency (rather than a frequency register), and always spends an integer number of clocks (output samples) on each input sample. However, it suffers from imaging (a reconstruction artifact) due to using a stair-step (zero-order hold) as a reconstruction filter. And IMO reconstruction artifacts sound worse (not harmonically spaced) when the sampling rate isn't an integer multiple of the note's frequency (the note pitch's period isn't an integer number of samples). Aliasing (a sampling artifact) is an issue in synthesizers which run at low/fixed sampling rates and sample waveforms to produce output (often using frequency registers). This includes modern software synthesis, and also hardware like DS (ZOH, samples, almost like Amiga), N163 (ZOH, short wavetables), Yamaha (FM on sine waves, IDK the details), and to a lesser extent SNES (Gaussian reconstruction, samples). Reconstruction artifacts (extra frequencies at x * fundamental, may exceed sampling rate) are different from sampling/aliasing artifacts (frequencies are taken modulo the sampling rate). But they can combine (like on DS hardware).
ssalazar 6y ago
Brian Eno’s quote comes to mind: > Whatever you now find weird, ugly, uncomfortable and nasty about a new medium will surely become its signature. CD distortion, the jitteriness of digital video, the crap sound of 8-bit - all of these will be cherished and emulated as soon as they can be avoided.

by mrob 6y ago

nyanpasu64 6y ago

In my (pedantic) understanding, the Amiga doesn't suffer from aliasing, because it uses a period register used to divide a very high frequency (rather than a frequency register), and always spends an integer number of clocks (output samples) on each input sample. However, it suffers from imaging (a reconstruction artifact) due to using a stair-step (zero-order hold) as a reconstruction filter. And IMO reconstruction artifacts sound worse (not harmonically spaced) when the sampling rate isn't an integer multiple of the note's frequency (the note pitch's period isn't an integer number of samples). Aliasing (a sampling artifact) is an issue in synthesizers which run at low/fixed sampling rates and sample waveforms to produce output (often using frequency registers). This includes modern software synthesis, and also hardware like DS (ZOH, samples, almost like Amiga), N163 (ZOH, short wavetables), Yamaha (FM on sine waves, IDK the details), and to a lesser extent SNES (Gaussian reconstruction, samples). Reconstruction artifacts (extra frequencies at x * fundamental, may exceed sampling rate) are different from sampling/aliasing artifacts (frequencies are taken modulo the sampling rate). But they can combine (like on DS hardware).

ssalazar 6y ago

Brian Eno’s quote comes to mind: > Whatever you now find weird, ugly, uncomfortable and nasty about a new medium will surely become its signature. CD distortion, the jitteriness of digital video, the crap sound of 8-bit - all of these will be cherished and emulated as soon as they can be avoided.