[linux-audio-user] Progressive Quantisation (long)

Folderol folderol at ukfsn.org
Tue Jun 13 19:00:13 EDT 2006

Well I don't know if this term actually exists or if I've just invented

This is an idea I've thought about for quite some time, years in fact,
but don't have the programming ability to try to put it into practice.
As I think it should really be part of, or a plugin to a sequencer I've
posted to LAU & Rosegarden lists. I hope nobody minds. I'd be very
interested in other people's thoughts on it.

Preamble over :)

All the quantisation systems I've seen so far only work if the music
has reasonably constant timing, and then produces much to rigid a
structure for my tastes.

When playing without a metronome (which always inhibits me) I find that
in a very long piece, I sometimes gradually speed up or slow down. This
is often only noticable if you go back to the start of a piece and
replay it immediately it has finished. If 'standard' quantisation is
applied to this then the results can be quite grotesque as notes fall
outside the quantisation capture range and get placed into the wrong

What I would like to see is quantisation algorythm the detects trends
rather than absolute values, then progressively applies small
corrections the keep overall timing correct. (it would of course have
to operate over all tracks simultaneously).

For example. The musician could put markers on notes in, say, an
accompaniment section, that aught to fall on the first beat of a bar.
The quantisation would then stretch or shrink the time positions so
most of these fit, and intervening notes of ALL tracks are adjusted
a proportionate amount. Later bars can then be interpolated and
occasional bars that don't actually have a note on the first beat will
still be adjusted based on averaging. Deliberate note delays,
syncopation etc. would then be perfectly preserved and the music would
retain its liveliness.

Having the musician place these markers rather than some automatic
system, means that not only are the correct notes used as a reference,
but the music can be brought into line even if it initially has
absolutely no relation to the bar lines in the sequencer (this happens
to me a lot when I try to record live). Overall timing can then of
course be set be altering the beat rate.

This whole idea could then be turned on it's head. I find it VERY hard
to get several tracks to slow down at the end of a piece and stay
'together'. This quantisation system could do just this by having
'target' time/beat rates at the start and end of the section that is to
be slowed (or speeded up).

Will J G

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