This is one of the Pd repertory patches.

CONTENTS

1. Overview
2. Effects network
3. Oscillator bank
4. Sampler and Markov chain player

Pluton (1988), by Philippe Manoury, is a piece for piano and computer lasting about 48-51 minutes. The computer senses the performer's piano playing through a MIDI interface. This is used to synchronize the computer with the piano (using score following) and also as a source of additional control. Manoury explores the idea of using the pianist's interpretation of the score to control various parameters of the computer's actions.

These computer actions take the form of synthesis, processing of the piano sounds, and spatialization. Using 2000-vintage hardware, the setup of the piece is as shown:

The piano only requires MIDI output, not input. At least two companies are now selling kits to retrofit essentially any piano for MIDI output.

The six speakers are arranged as a pair close to the piano on stage (the sound of the speakers is to blend with the piano's sound) and the other four arranged in a rectangle around the audience; these are sometimes used for two-dimensional panning spatialization, and sometimes pointillistically, that is, with individual sampler voices appearing out individual speakers.

The computer processes can be divided into three parts: first, a network of effects devices (reverberation, pitch shifting, and frequency shifting); second, two sampler banks, each with a unique Markov chain device and a granular time-stretching machine; and third, an oscillator bank whose amplitudes can be controlled by the analyzed, time-varying spectrum of the piano sound, making a sort of vocoder.

These elements are arranged as shown:

ptof - piano
ttof - sampler (the "t" stands for "Trevor" for historical reasons)
otof - oscillator banks 1 and 2
Otof - oscillator banks 3 and 4
rtof - reverberator 1
Rtof - reverberator 2
htof - pitch shifter ("h" for "harmonizer")

These values are all on a MIDI scale, with 127 meaning "unity gain." Originally they were all restricted to the range 0-127, but this restriction might no longer be in force.

Then there are three controls to set the frequency shifter's behavior:

fsfre - frequency (actually MIDI pitch) of shifting
fpos - positive frequency shift gain
fneg - negative frequency shift gain

In the original patch these controls are all limited to integers; you can probably use decimal values anywhere you want now.

The frequency shifter output can go to any of the other effects, or to the speakers. The speaker sends are in the control window:

fto2 - send to stereo pair in front
fto4 - send to the quad spatializer

These are not the only possible outputs for the frequency shifter; it can also be sent to any of the other effects (the two reverberators and the pitch shifter.)

The pitch shifter

The pitch shifter has the memnomic "h", and the inputs to it parallel those of the frequency shifter; so for instance "ftoh" means "frequency shifter to pitch shifter." The whole list is:

	ptoh ttoh otoh Otoh rtoh htoh ftoh Rtoh

Note the "htoh" which is feedback from the pitch shifter to itself; the other modules don't have this feature. The output levels, "hto2" and "hto4," are as in the frequency shifter. The pitch shifter's intrinsic controls are:

    hdel - delay, 4 milliseconds per step (so, 0-512 msec range)
    diramp - direct ("dry") amplitude, 127 for unit gain
    hamp - frequency shifter amplitude, 127 for unit gain
    hwind - window size, in logarythmic units, 200 msec maximum
    hfreq - frequency of change of delay time, one unit per 0.13 Hz.,
	with 64 being "none".  This controls pitch shift depending on
	window size; set this by ear.

The reverberators

    ptor ttor otor Otor htor ftor

    rgate - input gate, i.e. master input send gain
    rout - output level gain
    revfb - reverb feedback, which controls reverb time. 127 gives infinite
	reverb.