[sdiy] Oscillator sampler with sorting capabilities concept

[Paul Anderson]

I think it would probably sound like increasing amounts of static, until you get to the point of a saw. You'd be creating discontinuities in the wave, and those tend to sound like clicks. 

A counter-proposal: Take the derivative of the wave, and use that derivative to control the slope(and hence frequency) of a sawtooth. 

--------
Paul Anderson
Facilities Manager
Hackforge

On 2013-05-19, at 7:17 AM, Jim Credland <jim at cernproductions.com> wrote:

> 
> I don't know if it would sound good, but I'm very interested.   I'm also wondering what happens if you do one iteration of a sort between each cycle of a waveform.  You could start with just noise … it might sound like a boring waveform cross-fade, but it might not :)
> 
> How far did you get with the pure data implementation? 
> 
> cheers! J. 
> 
> 
> 
> On 18 May 2013, at 09:30, "cheater00 ." <cheater00 at gmail.com> wrote:
> 
>> Hi guys,
>> I was wondering what you guys thought of this synthesis technique. Has
>> anyone tried this? Could it sound good?
>> 
>> Here's a chat log between me and a fellow synthesis fan.
>> 
>> have you ever tried running a waveform through a sorting algorithm?
>> That is, take each cycle and sort that. If you sort the waveform fully
>> you should get something like a saw. But you could limit the amount of
>> work the sorting algo can perform before the waveform cycle is
>> released. If you put this parameter on a knob then you could perhaps
>> have a somewhat-smooth transition from your current waveform to a saw
>> waveform.
>> 
>> I think it could even work for analogue synths, you'd just need
>> somewhat of a buffer
>> 
>> 
>> you could have a sampler which works like this: it has a sync input
>> and a wave input from a VCO. when the vco outputs sync, it starts
>> sampling the waveform until the next sync. Once that's done, this is
>> called "a wave". Now for the output. Every time a wave is sampled, it
>> is placed on a queue (fifo). When a vco sync happens, the output
>> module takes the next wave from the fifo and starts outputting it. As
>> long as the wave is being output, syncs can be ignored (or instead, it
>> could jump to the next waveform at index 0, or to the next waveform at
>> the same index as it currently is). If there is only one wave left in
>> the queue, and the device is getting sync pulses over and over, then
>> it could either start outputting silence, or start outputting the last
>> wave it had in the queue.
>> 
>> 
>> this way it could work even delay-less (but would mangle the output in
>> a fun way)
>> 
>> 
>> Snd of course, while this happens the currently output waveform could
>> be mangled by: sorting, randomizing, sorting or shaping according to
>> the current waveform shape in a second sampler, etc.
>> 
>> 
>> could be fun when run on FM oscillators which change pitch.
>> 
>> 
>> So what "slaving to another sampler" would mean is that, in the master
>> sampler you have the sorting algorithm, and it moves sample 4 to
>> position 1. Then the slave sampler doesn't sort its own samples,
>> instead it just moves sample 4 to position 1, just like the master
>> sampler. I think this might only work if the wave are "normalized" to
>> some length, or alternatively if the waves in the slave get resampled
>> to the length of the master, or alternatively if the waves in the
>> master get resampled to the length of the slave. Resampling slave to
>> length of master would mean we either get a nice low-pass effect (if
>> the resampling is band-limited) or we get frequency-dependent aliasing
>> (if the resampling is not band-limited). The aliasing would not change
>> position in an inharmonic way like it usually happens when you alias
>> against a static sample rate (like when recording to a low sample rate
>> interface); instead aliasing would add a timbral quality which would
>> be constant across the keyboard, and work in a musical fashion.
>> Because both the master and slave waveforms are sampled at the same
>> clock rate, this aliasing process is immune to the clock rate of the
>> samplers.
>> 
>> You could laso have the master send the current wave to the slave and
>> you could have the slave use it to wave-shape its wave with that. So
>> if the master has a rising saw, nothing happens, and if master has a
>> sine wave, then you get a sine shaper.
>> 
>> If the master sends a wave, where the voltage level of the nth sample
>> is instead replaced by the index it has after being sorted, then
>> "slave sorting" could work simply by wave-shaping the slave wave by
>> that master "sorting index" wave.
>> 
>> 
>> Of course you could have the slave have its own sampling input and
>> sampling sync input, but then have its *output* sync to the master's
>> sync input or a dedicated output-module sync input. Then if the sample
>> memory is really long, and the sync happens every now and then, you
>> could have a stutter effect.
>> 
>> 
>> You could even have "markers" in the wave, which happen when a third
>> input is triggered. Then, once the output module get sync, rather than
>> jump to the beginning of the current wave it could jump back to the
>> latest marker or skip forward.
>> 
>> 
>> And if you have a long sample memory then you can just trigger the
>> input sync once and have a loop play forever.
>> 
>> 
>> I wonder what everyone thinks of this?
>> 
>> 
>> This is fairly similar to some of the stuff I did in Pure Data at some
>> point, but I've only now figured out how this could fit into the
>> context of a modular synth.
>> 
>> 
>> Cheers,
>> D.
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