Saw Bob Moog a number of years ago at the Fairlight suite at an AES
Convention in L.A. do a morph on a Fairlight II. He did it with 
continous waveform and a light-pen. Starting with a Square morphing to
a ramp, then to  triangle, then to a sawtooth. All the time watching 
the morphing on the screen go from waveshape-to-wavshape. Then he
demonstrated the 3-dim display of different wavforms, freq on the 
Z-axis, amplitude on the Y-axis and time on the X-axis. Then he 
rotated the disply a little.

Morphing on an interesting level.

It was pretty cool.


-Partev


================================================================



--- obrandts@gmail.com wrote:

From: Oeyvind Brandtsegg 
To: csound@lists.bath.ac.uk
Subject: [Csnd] Re: Re: Dynamic wave shapes
Date: Sat, 20 Mar 2010 01:52:22 +0100

Just a shot in the dark, but since these waveforms are all constructed
by adding sinusoidal harmonic components, wouldn't it be possible to
morph between the waveforms by controlling the amplitude of each
harmonic separately ? Obviously, one would need some of the harmonics
in different phase flavors (as e.g. the triangle wave has every second
component phase inverted), but such a doubling of some harmonics need
not be very expensive CPU-wise? The amplitudes for each harmonic
component could be stored in a table(one control table for each
desired waveform), and then use ftmorf to create the transition
(writing to the table used to actually control the synthesis
parameters). Bandlimiting could be achieved by simply calculating the
available number of harmonics below Nyquist, and since the amplitude
of each harmonic is continuously controlled this would allow for
correct bandlimiting even if the tone has pitch sweeps.
Oh, admittedly it's a "brute force" approach, but some optimization
could be done to not process oscillators with zero amplitude. And of
course PWM effects would need some special handling, I'm not sure but
maybe opcodes like pdhalf could do some of that, or use phase
modulation (synchronized to the base pitch) on all oscillators.

Oeyvind

2010/3/20 Michael Gogins :
> The problem here is aliasing... you can't just draw the shape in a
> wavetable and be done with it, and for the same exact reason you can't
> just draw a sharp shape and be done with it. The shape has to be
> smoothed to avoid aliasing, i.e. the square corners have to be curved
> or have some sort of sinusoidal component, else the infinite number of
> partials implied by the discontinuous click at the sharp corner will
> fold over the Nyquist frequency and be heard as things you don't want
> to hear.
>
> The bandlimited simple waveforms in Csound are done in different ways
> to avoid this, and I frankly don't know if any of them admit of
> continuous gradual changes in waveform. I know that it is possible to
> continuously vary waveshaping distortion so I think that something
> like this probably is possible, but somebody like Victor would know
> better than I.
>
> Hope this helps,
> Mike
>
> On Fri, Mar 19, 2010 at 5:58 PM, David Bowen  wrote:
>> The conversation about analog synths got me looking at the Moog web
>> pages and, in particular, the Mini Moog. If I understood the demo
>> video the oscillators had some wave shapes that were continuously
>> variable via a control knob. One example was a rectangular wave, think
>> a square wave but with the high and low sections of the wave having
>> different lengths.  I believe the other was a variable triangle wave.
>> Is there a Csound opcode for either of these? If not, is there an easy
>> way to create them with existing op codes? Obviously, you could change
>> the wave table every time the wave shape parameter changed, but that's
>> going to be much more effort if the wave shape is changing at a rate.
>> The code to implement them shouldn't be complicated, so if they don't
>> exist I may have to code them up myself, but I'm inclined to think I'm
>> just not seeing them in the Manual.
>>
>> Dave Bowen
>>
>>
>> Send bugs reports to the Sourceforge bug tracker
>>            https://sourceforge.net/tracker/?group_id=81968&atid=564599
>> Discussions of bugs and features can be posted here
>> To unsubscribe, send email sympa@lists.bath.ac.uk with body "unsubscribe csound"
>>
>>
>
>
>
> --
> Michael Gogins
> Irreducible Productions
> http://www.michael-gogins.com
> Michael dot Gogins at gmail dot com
>
>
> Send bugs reports to the Sourceforge bug tracker
>            https://sourceforge.net/tracker/?group_id=81968&atid=564599
> Discussions of bugs and features can be posted here
> To unsubscribe, send email sympa@lists.bath.ac.uk with body "unsubscribe csound"
>
>


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