Oscillators in VSTi?

[teacue]

Not sure if this questions belongs to another forum?

What are oscillators in most VSTi?

I understand what a VCO and a DCO are.
I believe that I aproximatively understand what a digital oscillator is, I found this:
"A digital oscillator stores the single cycle wave shape in a table of discrete values in a program."

But I am very unsure about oscillators in software.

Are oscillators in a VSTi calculated with an algorithm or a formula or are they in the end samples?
What is an oscillator shape for example in Vengeance Avenger?
And what is the difference (always in Avenger) between an oscillator shape and a wave for a wave table?
(I am not talking about samples or multi samples for Avenger)

In Parawave Rapid it seems that oscillators are waves for a wave table.

[gentleclockdivider]

Back in the old days , oscillators were analogue
VCO = voltage controlled oscilators .
Then came the digitally controlled analogue oscilators = DCO .( much more stable ) , roland juno 106 ..these were still analogue but were clocked to a digital source ...the soundgenerating was still analogue

IN a soft synth an oscillator is always digital , but it can be a single cycle wavetable ( pointer that reads from a lookuptable ) or it can be a virtual analogue osc , that is a mathematically generated waveform , first introduced on the clavia nord lead 1 .
If the square wave can do pulse width modulation , 99% percent that it's a math.gen.osc.
I have no idea how avenger's osc's are generated .


Some companies don't say anything about the generating process of their osc's , like some roland marketng bullshit ...selling it as V.A. osc, while in facts it's a simple lookup table .

[] Peter:H []

Not sure if this questions belongs to another forum?

What are oscillators in most VSTi?

One example - Oscillators as computed by an formula on the fly.
Please read Martin Finks Tutorial/Blog on how to implement a VSTi. He has some very good chapters about Oscillators. In case of the tutorial the basic waveforms like sine, square, triangel are computed by an formula on the fly. He also adds some theory about "aliasing" and how ripples help to get rid of it...It's an pretty interesting read http://www.martin-finke.de/blog/article ... roduction/

Please read the whole series...it's woth it...shortcuts
1.) First Chapter of the series that deals with implementing an OSC: http://www.martin-finke.de/blog/article ... waveforms/
2.) Addon for how "PolyBLEP" helps: http://www.martin-finke.de/blog/article ... scillator/

[teacue]

@gentleclockdivider
Thank you for your answers, it helps me a lot.
About the specific VSTi I will then directly ask the developper.

@Peter:H
Thank you for your suggestions, it looks very interesting.

[fluffy_little_something]

I have difficulty understanding what makes a sine sound like a sine in the first place. Are all waveforms (from sine all the way to complex, exotic ones) just amplitude changes over time, the way the axes of diagrams are named? If so, amplitude of what? "The signal" I suppose. But what is that?
Since there is just one amplitude at any moment in time, is it the fast succession of changes of the amplitude of the same signal that creates the illusion of different sounds in our heads?

[nix808]

The best I can do Fluffy mate,
is an energy called sound.
We can generate with only a AC kinda setup

[whyterabbyt]

Are oscillators in a VSTi calculated with an algorithm or a formula or are they in the end samples?

A software oscillator is an algorithm, one that digitally generates a signal to a specified frequency. That 'specified frequency' bit pretty much means that there's always some sort of algorithm in there, even if all the oscillator does in terms of the waveform is look up a precalculated single-cycle waveform data source and resample that to the required frequency.

More sophisticated oscillators can be based on more complex algorithms, 'up to' entirely algorithmic calculation of the waveform with no usage of a data source. Some synthesis methods, though, (eg scanned multi-cycle wavetables,) intrinsically rely on data sources.

'Data source' in this context can be 'sample' or 'wavetable' or whatever name for a stored waveform you want to use.

[nix808]

In digital, they are ultimately samples of sound,
like a numeral each.
Each numeral exists within frequency and amplitude, ie.
hz(frequency) and bit depth(amplitude)

Like stop-motion video, 2000 times faster

[whyterabbyt]

I have difficulty understanding what makes a sine sound like a sine in the first place.

Nothing makes that happen. That's how sine waves sound. Might as well ask what makes blue look blue; blue is the name for how blue looks. 'sine' is the description of a specific property, the property is intrinsic to things thus described.

Are all waveforms (from sine all the way to complex, exotic ones) just amplitude changes over time

Yes. If it doesnt change amplitude, it isnt a wave.

If so, amplitude of what? "The signal" I suppose. But what is that?

The signal is a signal, delimited by the context of the signal you're talking about. If you're presuming there is an observable/measurable amplitude change over time in some substrate then 'signal' is the word for that change. If you're talking about something audible, then the signal is a set of amplitude changes in air pressure over a specific period of time, within the frequency range we consider audible, summed at two separate physical positions defined by the location of the observer.

Since there is just one amplitude at any moment in time, is it the fast succession of changes of the amplitude of the same signal that creates the illusion of different sounds in our heads?

No, its our brain's ability to analyse them and decompose them back into sets of coherent 'subsignals' congruent with the original source signals.

[ENV1]

I have difficulty understanding what makes a sine sound like a sine in the first place. Are all waveforms (from sine all the way to complex, exotic ones) just amplitude changes over time, the way the axes of diagrams are named?

Dont think of waveforms as 2-dimensional things. (They are not.)

There are actually 3 dimensions, namely Time, Amplitude and Phase.

(4 actually if you count Polarity as well.)

For instance a Sine. It doesnt just go 'up and down' as the familiar 'side view' would suggest. When you look at it from an isometric perspective it looks like a snake coiling forwards around a pole. It goes around 360 degrees evenly and smoothly, which gives it its typical shape when viewed from the 'side'. The sound is a result of that even-/smoothness.

(It coils 'backwards' in the animation but it was the best i could find. You get the idea.)

[nix808]

Hey ENV1,
that was a cool post ty,
but I think quadrature is more of a coding unit than necessarily what sound does?
Phase is time also as time hehe

[fluffy_little_something]

Sounds complicated. I indeed always thought of it as a two-dimensional thing. Like with loudspeakers where the signal amplitude determines how far the membrane moves back and forth, and the way the membrane accelerates (both positively and negatively) to and from the peaks over time determines the character of the sound.

Sure a sine sounds like a sine, but those are just words. Just like blue is just a word, but it has a very specific physical background. With sine it is the extreme simplicity I think, no harmonics.

[Dasheesh]

Some of the better and most beautiful oscillators were done per cycle. That became too CPU expensive for the EDM crowd though so they had to come up with a less expensive way of doing things. These days a lot of the newer ones are MIP mapped. I'm far from a know how, but my impression is that they map a shape then copy it FFT style with a fine resolution, then frequency scale it to the keyboard by shortening the length.

viewtopic.php?t=264824

[nix808]

excitation of an atmosphere is worth a mention,
when there are radical changes- they are more noticeable to the ear(sine vs square).
But a square has more energy DC speaking too.

IMO-it really is the action of a speaker cone that creates it(just in and out),
but natural sounds are some sort of atmosphere disturbance too

[lobanov]

We also could say that every digital oscillator produces numbers. They can be precomputed (and read from a lookup table) or computed in realtime. We hear sound because of digital-to-analog conversion (DAC).