Re: PATCH: Issue 638 Autobeaming

[Trevor Daniels]

Carl, you wrote Friday, December 18, 2009 4:21 PM

> On 12/18/09 2:49 AM, "Trevor Daniels" <address@hidden> 
> wrote:
> > A question.  Does your code require autobeaming
> > rules to be defined for beams of every possible
> > duration?  I ask because the following example beams
> > inconsistently, and I'm not sure if this is due to your
> > code or differences in the autobeaming rules for 4/4 and
> > 2/2 time signatures.  With a32 instead of a64 a64 the
> > beaming is fine.
>
> The current design is that unless a beaming rule is specified for 
> a given
> duration, the default beaming rule is used.

I mentioned this example because the beaming with
your patch is inconsistent when the 64th notes are
present because they cause the rule for 32nd notes
to be ignored.  This is a change from the previous
behaviour.

> For 2/2, the default rule is break at (1 . 2), with 1/32nds 
> breaking at
> every (1 . 4).  I'm not sure that this is the best possible rule. 
> After
> all, I'm not an expert in beaming.

Me neither :(

> Would it be better to have it follow the 4/4 rule: by default 
> break at every
> (1.4), and have 1/8 notes break at (1 . 2) ?  I expect that that 
> is what
> Read is saying.

I don't have access to Read, but this from Ross may
guide us:

"In simple time any beat divided into more than two
parts cannot be connected to another beat [with a
beam] to form a unit."  Now he doesn't say that the
converse is true, but maybe we can assume it is for
the default beaming.  Hence in 2/2 we should not have
a default break every 4th - the default should be to
break on beats, ie at 1/2.  We're left with the question
of what to do within a beat when 16th, 32nd or shorter
beams are present.  Ross is silent on this point.  But
I would suggest we treat them exactly the same - beam
to 1/2.

> If so, this is a simple rule change.

Yes.

> I think that the default rule set is probably not correct, and 
> needs a more
> thorough reading.  I'll try to get to that today.

OK.  Maybe the best plan is to simplify where possible.
I think I might have been responsible for adding the
32nd rules, but I'm no longer sure this was wise in
some of the cases, like 2/2.

> Carl

Trevor