a577@mindlink.UUCP (Curt Sampson) (09/02/90)
I think I read somewhere that PD synthesis just reads a sine wave from a table
at varying speed. If you controlled the speed at which your read the data from
the table and output it with the function cos(x) with x varying from pi-->2pi
across the first half of the sine cycle (sin(x) x varies 0-->pi) the sine wave
would be "lopsided" and tend to "lean" to the right, forming more of a sawtooth
wave.
Of course, given the correct software "engine," you could do this with any
function on any waveform, or even with one waveform on another. Now this does
sound like an interesting method of synthesis. Perhaps I should get a MIDI
interface and start generating some samples for my EPS...
Sorry if the math is a little off. It's not my strong point, and it's been a
couple of years.
-cjs ( Curt_Sampson@mindlink.UUCP )cho@aber-cs.UUCP (C.H. Orgill) (09/02/90)
Can anyone point to a mathematical definition of the term 'phase distortion' as implemented by Casio in their VZ-1 synthesizer ? Is this topic covered in the Moore book ? Ta, Chris Orgill, tel +44 970 622447 Research Associate, Computer Science Department, cho%cs.aber.ac.uk@uunet.uu.net (ARPA) University College of Wales, cho@uk.ac.aber.cs (JANET) Aberystwyth, Dyfed, United Kingdom. SY23 3BZ.
sinistar@uiuc.edu (Jeff O'Hare) (09/04/90)
cho@aber-cs.UUCP (C.H. Orgill) writes: >Can anyone point to a mathematical definition of the term 'phase >distortion' as implemented by Casio in their VZ-1 synthesizer ? Is >this topic covered in the Moore book ? Check the manual for a decent description! If you need help.. mail me.
sandell@ils.nwu.edu (Greg Sandell) (09/04/90)
Charles Dodge and Thomas Jerse authored a computer music textbook (can't remember the title, but it has "computer music" in it), published by Schirmer, which has a description of the phase distortion technique in the chapter "Distortion Techniques." Hope this helps. The book was published around 1986 or 1987. **************************************************************** * Greg Sandell (sandell@ils.nwu.edu) Evanston, IL * * Institute for the Learning Sciences, Northwestern University * ****************************************************************
scott@bbxsda.UUCP (Scott Amspoker) (09/05/90)
In article <3029@mindlink.UUCP> a577@mindlink.UUCP (Curt Sampson) writes: >I think I read somewhere that PD synthesis just reads a sine wave from a table >at varying speed.... > >Of course, given the correct software "engine," you could do this with any >function on any waveform, or even with one waveform on another. Now this does >sound like an interesting method of synthesis... Yes, I believe it's called FM (unless I'm missing something here). -- Scott Amspoker Basis International, Albuquerque, NM (505) 345-5232 unmvax.cs.unm.edu!bbx!bbxsda!scott
alves@alcor.usc.edu (William Alves) (09/05/90)
In article <2010@aber-cs.UUCP> cho@uk.ac.aber.cs (Chris Orgill) writes: >Can anyone point to a mathematical definition of the term 'phase >distortion' as implemented by Casio in their VZ-1 synthesizer ? Is >this topic covered in the Moore book ? > What Casio calls phase distortion synthesis is also called non-linear distortion or waveshaping. (Companies always have to invent new names for things to make it seem like they invented it.) I don't have the Moore book handy, but it is covered in Dodge and Jerse _Computer_Music_ (1985) and more in depth in an article by Marc LeBrun "Digital Wave- shaping Synthesis" in the Journal of the Audio Engineering Society #27 (1979). Bill Alves
smithj@hpsad.HP.COM (Jim Smith) (09/07/90)
Scott Amspoker scott@bbxsda.UUCP mentions that he believes that phase distortion synthesis is the same as FM. It isn't, because the phase is distorted synchronously with the carrier. In other words, in FM, the frequency ratio can be anything including non-integer ratios, but in phase distortion, the ratio is always 1:1. Also, the modulator is not necessarily a sine wave. Phase distortion synthesis is more akin to running the phase increment of a digital oscillator through a lookup table prior to running it through the sine wave lookup. I'm not sure this clears up anything, but what the hell... ----------------------------------------------------------------------------- | Jim Smith | e-mail: smithj@hpsad.HP.COM | | R&D Firmware/Software QA | Telnet: 794-4632 | | HP Signal Analysis Division | AT&T: (707) 794-4632 | | 1212 Valley House Dr. | HPDesk: Jim M Smith/HP5300/I0 | | Rohnert Park, CA 94928-4999 | HP Mailstop: 2LR-D | | Everybody wants a rock to wind a piece of string around. - TMBG | -----------------------------------------------------------------------------
scott@bbxsda.UUCP (Scott Amspoker) (09/07/90)
In article <2650003@hpsad.HP.COM> smithj@hpsad.HP.COM (Jim Smith) writes: >Scott Amspoker scott@bbxsda.UUCP mentions that he believes that phase >distortion synthesis is the same as FM. For the record, I did not exactly say that. I have no knowledge of "phase distortion" and would not make such a statement. Another poster attempted to describe phase distortion and I pointed out that what he wrote sounded just like FM. Later, another net reader explained to me, in private email, that phase distortion is basically a subset or limited form of FM. -- Scott Amspoker Basis International, Albuquerque, NM (505) 345-5232 unmvax.cs.unm.edu!bbx!bbxsda!scott