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staring at the NES triangle wave channel waveform
- hey that looks like it's based on a LUT
- ...the volume can't be edited, it must be a LUT! (multiplies are expensive)
- wait why isn't it a sine wave
- ah but sine waves suck
- oh wait, this actually is a sine LUT used "wrong"!
see, the stairstep pattern presumably comes from it using a look-up table (LUT) that has the samples for the first quadrant of a sine wave. to fill out the other four quadrants, you'd horizontally flip, vertically flip, then both horizontally and vertically flip. but it doesn't!
instead it just alternates between unmodified and vertically flipped. it also doesn't have the biasing/subtraction from zero you'd need for a sine
and the result is one of the most beautiful bass sounds in the world
i need famicom bossa nova. please send famicom bossa nova
waveform from this video btw https://www.youtube.com/watch?v=HmJP5EFUEpw
to prove my point, this sine wave is what you get if you do the flips i described on just that ascending portion of the wave
stop the presses, we have been informed that a high-pass filter is what makes it look sine-shaped? it's actually just a pure stairstepped triangle wave originally?
this is what's funny about stairsteps in audio, they're an intermediate step and a simple filter can turn them into pure sine waves or anything in-between if you want that. the "DACs produce stairsteps" thing is a myth
this is also how you find out we have never done synthesis stuff in an actual DAW where we could see what we were doing ^^;