Morphing between waveforms...

Was trying to figure something like this out myself a few weeks ago. Tips from those who know, please!

if you have one wave~ object with a sine wave and one wave~ object with a square wave, drive them from the same phasor~ and then crossfade between the outputs. if they're on the same phasor the output will be synced and the result will be a "morph" between the two waveforms. it is totally not cheating! you can check it with the scope~ object.

(equally you could use a cycle~ object and rect~ object and drive their phase inlet with the same phasor~. but wave~ lets you use any waveform...)

maxd wrote on Mon, 02 March 2009 20:20HI list,

I am looking for a system to make interpolations between waveforms.

I want avoid too use a switch but find a way to morph progressively a square to a sawtooth for example. Like some analogic oscillators do .

The phasor method will work well and be very simple to implement, plus using all kinds of waveforms are possible. With a bit more work you can combine multislider and peek~, whereby you draw in the multislider and its list value (512 samples, say) gets stored in the buffer~ for playback. With some math you can fill the multislider with sine, sawtooth, etc., or simply draw whatever waves you want. Then use [pattr] on the multislider at your interpolation endpoints, and use a [line] to move smoothly between them. It also looks very cool

The drawback is that this is considerably more processing. It still is fairly smooth but the phasor~ route will take a much smaller hit. However you'll have a GUI for absolutely any waveform you want, plus you can load wave samples into the multislider using peek~ (reading from it instead of writing to it), save those in your pattr, then morph between them (snare hit to violin, speaking "ahh" to "ooh", etc...) You can reduce the processor hit by hiding the multislider, or much more so, speedlimiting how often its list goes out and is written to the buffer~ using peek~. Of course then you'll get "steps" in your interpolation that will be more noticeable than a smooth crossfade with the phasor~.

Simple crossfading does work great, as long as the relative phases of the waveforms are correct. This can be a little tricky to get right with rect~ and saw~ because one can't rely on them to start up with consistent phases relative to cycle~. Sending sync from another cycle~ offset in phase, as in this patch, makes it work consistently.

Fading between arbitrary waveforms indexed with a phasor~ can work, but you will have to oversample the **** out of it unless you don't mind aliasing.

-Randy

With 2d.wave~ it is possible to morph between subsequent waveforms on audio rate in a clean way. Fill a buffer with subsequent cycles and have a look at the help file of 2d.wave.

_
johan

maxd wrote on Tue, 03 March 2009 03:20I am looking for a system to make interpolations between waveforms.

An alternative to 2d.waveform is the lp.frim~/lp.tim~ group of objects in Litter Power. They implement Larry Polansky's 'mutation' algorithms.

The objects are extremely powerful but not easy to use. To some extent they presume familiarity with the Mutation function in SoundHack (or any of the other implementations of mutation out there in the world). I've gotten great sounds out of the objects.

Lp.tim~ is part of the free Litter Starter Pack. For lp.frim~ (the big brother;-) people need to pony up for Litter Pro. As my mother always said, you get what you pay for.

Thanks for all yours answers guys....

but Someone could send me the beginning of a patch or an exemple??
Because I use Max a lot but I never made synthesis and it's really complicated to understand your language.

Thanks a lot

Max

[2d.wave~] is a powerful beast, but may be difficult to use for a beginner.
Another option is to write both "source" waveforms in two jitter matrices, and to interpolate (for instance with jit.xfade) into a jit.buffer~, from which the sound is played back.
If you have never made synthesis, you can start in Max/MSP, of course! MSP tutorial 3 seems linked to your question. Do you find it useful?
Jean-François.

Here's an example using 2dwave~ that someone posted to the list some time ago,
cheers
Roger