Re: Auto-beaming infrastructure redo

[Trevor Daniels]

Carl Sorensen wrote Saturday, July 03, 2010 1:06 AM


> On 7/2/10 5:19 PM, "Trevor Daniels" <address@hidden> wrote:
>
> > Carl Sorensen wrote Friday, July 02, 2010 3:22 PM
> >
> > > I've got mixed feelings about the following property:
> > > 3) beatCombinations: an alist with a key of beam type,
> > > and a value of the beats that can be combined for that
> > > beam type.  This is currently only used for 3/4 and 4/4
> > > time, and it doesn't really capture the special rules used
> > > for 3/4 and 4/4 time (although it comes close).  I can't
> > > decide whether to create this general property and use it
> > > to define rules for 3/4 and 4/4 time, or whether I should
> > > just go ahead and hard-code the special rules for 3/4 and
> > > 4/4 time (so I could get them perfectly).
> >
> > My feeling is to hard-code these.  I've tried to think of
> > generic ways of parameterising them and failed.  The rule that
> > "a beat in simple time that is divided into more than two parts
> > cannot be connected to another beat" is the tricky one.  Nor
> > can I think of any other circumstance where such a rule might
> > be needed.
>
> Actually, that rule is pretty easy.  I just make it apply to only 
> 1/8 note
> beams.  It doesn't catch everything, but it mostly works.

Of course!  I was trying to find ways of counting stems!

> The hardest one is "don't split beat 2 of 3/4 into two parts". 
> I'm still
> not sure exactly how to implement that.

As we discussed earlier, this rhythm, f4 r8 f f f, could be
handled by implementing a 'start' rule as well as an 'end' rule,
to be sure beams could be started only on beats, couldn't it?

The other tricky combinations like f8 f~f f f f and d'4. c8 b8. a16
are not specific to 3/4.  The former applies to tied notes over
beats in any time signature, I think; it means beams should be
broken if there is a tie carrying over a beat, presumably to
ensure the tie is seen more clearly.  The latter of these two
is really tricky: the beam should be broken at the beat if the
rhythms in the two parts are similar but not identical.  Some
of the commonly occuring patterns could be trapped by beam
ending rules maybe, but implementing it in full generality?
Perhaps we let that one be resolved by manual beaming!

> Carl

Trevor