[PD] Re: [PD-announce] William Fields - Live at Open Source - Philadelphia, PA

William Fields bill at teamtechno.com
Wed Mar 10 23:20:27 CET 2004

Thank you for your enthusiastic responses!  I'll try to go into a little 
more detail...

Hmm... First of all, the system does not process audio at all.  I only 
have a 750mhz P3, and I found that trying to do control & audio at the 
same time was too much.  The timing was not stable enough, so I use a 
separate program to handle the audio generation / FX, and the pd side 
only generates MIDI / control data.  Audio is disabled in pd. 

Basically, my system consists of a number of "generator" patches, all of 
which use GOP.  There is one that plays MIDI files, there is one that 
generates patterns of notes in a given scale (which is set globally), 
there is one that generates chords, etc..  Each of these generators can 
be turned on or off, routed to any midi channel, and have a number of 
other parameters. 

Under the hood, it is simply generating, processing, and routing around 
<note,velocity,duration> vectors.

There are also a number of patches that spit out numbers: one that 
approximates an LFO, one that puts out random values within a given 
range at a given time interval, etc. etc.

There are a number of parameters that can be applied at the channel 
level or the global level:
- density (what percentage of notes are actually played)
- pitch (using pitch bend)
- repeat (sort of like delay, but it actually retriggers the note n times)
- velocity
- randomness (remembers the last n notes it heard and spits them back 
out randomly)
- duration (can modify the duration of all notes at once)
- etc, etc...

I have these different parameters assigned to knobs on my midi 
controller.  I also assign some knobs to pass control data through to 
the VST effects.

It uses a "pool" based preset switching system (thank you!), and I have 
the buttons on my midi controller assigned to jump between the presets.

When performing I only have a minimal amount of stuff on the screen, 
almost everything is hidden away because jumping between presets causes 
timing glitches due to all of the GOPs.

I hope that gives you a general idea...

If you're interested in hearing more, here's another live performance in 
which I used the pd system:

(download, 83MB MP3)   


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