Re: Imposing Swing Upon notes (Specification)

[Dean Radcliffe]

I have created a prototype scheme-based implementation which imposes
swing on streams of notes/rests which are quarter-note length or less
(still a few math problems to solve before its ready for any notes
thrown at it, or customizable amounts of swing, etc..):

http://music.chicagogrooves.com/lilypond-swing-dev.zip

Feedback and/or successive versions would be welcome !


On Sat, Jul 24, 2010 at 1:24 PM, Marc Hohl <address@hidden> wrote:
> Dean Radcliffe schrieb:
>>
>> I added the following to
>> http://code.google.com/p/lilypond/issues/detail?id=687
>>
>> I think this is a way to think about - could anyone suggest to a novice
>> schemer how this might be done ??
>
> Hello Dean,
>
> I thought about this issue some time ago. There is a file articulate.ly from
> Peter Chubb, and I thought
> about extending this to include swing. I worked on the mathematics behind
> this stuff, but it seems
> that it is not easy or even not possible to get the position within a bar
> (say, beat 1 or 2 + ...) while
> parsing (and this is the stage when articulate.ly joins in).
>>
>>
>> There is a quantity called "Global Groove Amount", and a setting that
>> controls whether it applies to syncopated eigths or syncopated sixteenths.
>> It is a number, from 0 to 100 (but most useful at and around 33), which -
>> for the eighth note example - is ignored on quarter note beats, but for
>> those syncopated eigth notes, displaces them later in time by the proportion
>> of 100 specified. Example: assuming 100 divisions per quarter note, the
>> syncopated eigth-note falls on 50 without swing, but with 33 groove factor,
>> the number 50 is increased 33%, and so becomes 66. Notes that are neither
>> exact eigth notes (which have full groove factor applied), or exact quarter
>> notes (which are unaffected by groove factor in eigth-note mode, much like
>> eigth-notes are unaffected in 'swing 16th' mode) can either be left
>> unaffected, or proportionally affected, dependent on a configuration
>> override (the default should be to leave them unaffected).
>>
>> This would not require lookahead, or collision avoidance, just the ability
>> to determine whether a given musical event is a downbeat per that
>> swing-mode, and the ability to alter the displacement of the note by the
>> product of the groove factor and a number that indicates how off-the-beat
>> the note is already. The visual representation of the note should not be
>> altered, nor other elements moved around, this only need take effect on all
>> audible events in midi output. This feature is basically the rhythmic
>> equivalent of transposition- music written one way, and played another.. but
>> instead of translating in the pitch domain, we are scaling in the time
>> domain, modulo the distance from certain interval boundaries. I would
>> actually suggest calling this a Swing_Performer, available only for midi
>> layouts (I'm not sure i have my terminology right here, but that's the idea,
>> in the same way you can add and remove Dynamics_Performer for midi output)
>
> Yes, this stuff has to go into some Performer, but I don't think that
> Performers can be coded in scheme,
> so it has to be done in c++.
>
> Just my 2ct...
>
> Marc
>>
>>
>>
>>
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>