[sdiy] Polyphonic voice allocation algorithm

[rburnett at richieburnett.co.uk]

Hi guys and girls,

Does anyone have a link or document that gives a good explanation for a 
basic polyphonic voice allocation algorithm.  I'm not after anything 
fancy, just the sort of process that goes on inside a basic mono-timbral 
polysynth like Roland's Juno series.

I know some basic terminology like "voice stealing" and "round robin 
fashion" but I'm trying to avoid sitting down and going through the 
thought process of coming up with my own voice allocation algorithm from 
scratch!  Life is too short to spend time re-inventing the wheel when 
this algorithm has been used for decades and must surely be documented 
somewhere?

I know synths like the Juno 106 had two different poly voice allocation 
modes on offer.  One of them assigns repetitive same notes to new voices 
in round-robin fashion so that their release phases can overlap, and the 
other mode plays the repeating same notes by just retriggering the same 
module.  What I'm really looking for is something like a flowchart, or 
text description of how the voice allocation decisions are performed.

I appreciate that things can get complicated when notes can arrive from 
local keyboard vs over MIDI, and things like Sustain messages, and 
multi-timbral setups are considered.  However, I'd like to keep it 
simple at the moment so that I can just play about with some synthesis 
options.

Thanks in advance for any help,

-Richie,