4 ms·

One kind of distortion that I loved to apply in my FastTracker II days, and which I don't see used all that often, is to flip the sign. In short, FT2's sample

One kind of distortion that I loved to apply in my FastTracker II days, and which I don't see used all that often, is to flip the sign. In short, FT2's sample editor could handle a few common waveform formats, but this was cross platform days and there were a lot of wave formats. These have differnt headers and different structures, but many of them ended up being just a series of samples, either in 8-bit or 16-bit, and at some sample frequency. To deal with this, FT2 added a button that let you reinterpret a waveform as if it was stored signed or unsigned, and one that let you reinterpret as 8/16 bit. This let it load a huge amount of sample formats well enough; you'd fiddle around with those buttons until it sounded right, then you cut the first few millisecs of noise (the file format header) off the front, and done! But turns out that the "reinterpret as (un)signed" button (called "Conv" in FT2) is pretty spectacular for nasty distortion too. Imagine a sine wave. Loaded correctly, it'll look like this: +-----------------------------------------------------------------------------+ | | | X| | XXXXX XXX| | X XX X | | X XX XX | | X | | X XX XX | | X X | | X X X | | X XX | +-----------------------------------------------------------------------------+ | X X X | | X X X | | X X X | | X XX | | X XX X | | X X | | X X X | | X XX X XX | | X XXXXXX X XXX | | | +-----------------------------------------------------------------------------+ Imagine this was stored as 8-bit signed. Now, if you reinterpret those bytes as unsigned, it'll look like this: +-----------------------------------------------------------------------------+ | XX XX XX | | X X X X X X | | X X X X X X | | X X X XX X | | X X X XX X X | | X X X X X | | X X X X X X | | X X X XX X XX X | | X X X XXXXXX X XXX X | | X X X | +-----------------------------------------------------------------------------+ | X X X | | X X X X| | X XXXXX X X XXX| | X X XX X X X | | X X XX X X XX | | X X X X | | X X XX X X XX | | X XX X X | | X X XX X X | | X X XXX | +-----------------------------------------------------------------------------+ Notice how the top half and the bottom half of the sine waves are swapped. Now, I don't understand much about DSP and sound and the frequency domain. Better programmers than me have told me that this makes no sense from an audio/music perspective. But it sounds pretty cool; you keep a lot of the essence of the original sound, and add a lot of nasty. I once made a VST plugin that does this (it lets you slide the waveform up, wrapping over to the bottom; its only parameter is by how much to slide), but I don't think I have it anymore unfortunately. For context, applied to a random bassdrum using 8bitbubsy's amazing Windows clone of FT2[0]: - original: http://neuvostoliitto.nl/808_drum_kick_035_21338.wav http://neuvostoliitto.nl/808_drum_kick_035_21338.wav - distorted: http://neuvostoliitto.nl/808_drum_kick_fucked.wav http://neuvostoliitto.nl/808_drum_kick_fucked.wav Just sharin' :-) [0] https://16-bits.org/ft2.php https://16-bits.org/ft2.php

hrnnnnnn 6y ago
I believe this is called wavefolding - there's a button for it in the demo which gives a very similar picture to yours.
im3w1l 6y ago
> Now, I don't understand anything about DSP and sound and the frequency domain. Without going into theory, just look at it. It's the addition of a square wave and a sine wave now. And a square wave has lots of harmonics, giving that buzzy sound.
- skrebbel 6y ago
  not entirely, because the square wave isn't regular. in graphical terms, the space between each time the square goes up and down is irregular. that gives it a totally different (and, notably, more atonal) sound than a normal square wave. also, the sine wave got flipped, half, kinda. just mixing a square wave with something has a totally different effect than this. it'll sound like the original sound and also a square wave tone playing together.
- louthy 6y ago
  > And a square wave has lots of harmonics A square wave is 100% distortion effectively. It's an infinite series of sine-waves (although the infinite series isn't needed to generate a square wave, just the sum of harmonics up to nyquist)
  - willis936 6y ago
    Well, no. In any finite range of frequencies there are infinitely more harmonics that are in a noise signal than are in a square wave. In the audible frequency and dynamic ranges, you realistically can’t perceive more than maybe 7 harmonics in a square wave and it sounds very different than a noise signal.
- willis936 6y ago
  I think it’s the multiplication of the two waveforms (aka mixing). The spectrums are convolved. It’s a common technique. Square waves are a fun case to explore here because you might start finding cases where something you might just consider 180 degree phase jumps (PSK) actually effect the magnitude spectrum (square wave). They don’t teach you that in school!

hrnnnnnn 6y ago

I believe this is called wavefolding - there's a button for it in the demo which gives a very similar picture to yours.

im3w1l 6y ago

> Now, I don't understand anything about DSP and sound and the frequency domain. Without going into theory, just look at it. It's the addition of a square wave and a sine wave now. And a square wave has lots of harmonics, giving that buzzy sound.

skrebbel 6y ago
not entirely, because the square wave isn't regular. in graphical terms, the space between each time the square goes up and down is irregular. that gives it a totally different (and, notably, more atonal) sound than a normal square wave. also, the sine wave got flipped, half, kinda. just mixing a square wave with something has a totally different effect than this. it'll sound like the original sound and also a square wave tone playing together.
louthy 6y ago
> And a square wave has lots of harmonics A square wave is 100% distortion effectively. It's an infinite series of sine-waves (although the infinite series isn't needed to generate a square wave, just the sum of harmonics up to nyquist)
- willis936 6y ago
  Well, no. In any finite range of frequencies there are infinitely more harmonics that are in a noise signal than are in a square wave. In the audible frequency and dynamic ranges, you realistically can’t perceive more than maybe 7 harmonics in a square wave and it sounds very different than a noise signal.
willis936 6y ago
I think it’s the multiplication of the two waveforms (aka mixing). The spectrums are convolved. It’s a common technique. Square waves are a fun case to explore here because you might start finding cases where something you might just consider 180 degree phase jumps (PSK) actually effect the magnitude spectrum (square wave). They don’t teach you that in school!