Re: Quantising problem

From: Alexandre Ratchov <>
Date: Sat Dec 08 2012 - 11:45:27 CET
On Sat, Dec 08, 2012 at 03:26:06AM +0100, Julien Claassen wrote:
> Hello everyone!
>   I had noticed that before, but attributed it to some fault of
> mine. When I quantise a track, notes get also changed to be VERY
> staccato. Consider this sequence:
> setq 8
> tquant 100
>   If I understood correctly from the manual, the tquant 100 should
> just move the notes to exact positions, but not shorten notes
> unduly.


With the current algorithm, any event is quantized, including
note-offs and controllers. Basically, the algorithm contracts time
around aligned note positions (1/8 notes) and dilates time around
wrong postions. This way events are pushed around aligned positions
while order is preserved.

Preserving order is important since reordering events may introduce
all kind of anomalies; example, this may create nested notes or
certain notes may escape the sustain pedal, etc..

>   Doing that, I also notice, that occasional notes are
> unproportionally long, in contrast to the staccato notes. They still
> fit their space, but the staccato notes are almost imperceivable.
> Any ideas about that? 

If a note-on event is sligtly early and the note-off is slightly
late, then the resulting note duration is smaller than the
original, which makes it sound more staccato. Similarly if the
note-on is late and the note-off is early, then the note duration
is increased and it sounds more legato.

The larger the quatization depth is, the more the effect is
audible. 100% is extreme, and will aggregate events at aligned
positions; the resulting notes durations become multiples of 1/8,
including zero duration. Probably imperceivable notes you observe
are zero-length notes.

> Any hints, how to improve the results?

Try using either a quantization step smaller than the typical note
duration or a smaller quantization depth (100% is really extreme!).

I use typically around 50% for piano, 75% for bass, 80-90% for
percussions and almost never 100%, maybe except for electronic

When notes are very short, I use half of the quatization step; this
requires playing more precisely the sequence; if so, either I lean
it better or I record it at around ~85% of the original tempo
(example "fac 85").

-- Alexandre
Received on Sat, 8 Dec 2012 11:45:27 +0100

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