Re: PATCH: Issue 638 Autobeaming

[David Kastrup]

Carl Sorensen <address@hidden> writes:

> On 12/18/09 3:58 AM, "David Kastrup" <address@hidden> wrote:
>
>> I think that if we establish the rule "a broken beam decision is
>> never reconsidered" we can abolish the '* rule for beaming patterns
>> and instead let a non-specified minimal duration always be broken
>> according to the time intervals of its next-larger cousin.
>> 
>> That would simplify the default patterns, not cause problems when new
>> lengths get supported, and make it harder for users to specify
>> patterns manually with accidentally undefined behavior.
>> 
>
> So which do you think does a better job of being clear as a (4 . 4)
> beaming rule:
>
> (( * . (1 1 1 1) ((1 . 8) , (4 4)))
>
> or
>
> (((1 . 8) , (4 4)) ((1 . 16) , (4 4 4 4)))

I'd say the latter, since the former requires
a) an additional special symbol
b) with its additional special timing unit that actually can't be
   guessed without looking at the time signature, too.

> Under your proposal, the second is equivalent to the first as it is
> currently implemented.

Yes.

> I can see some benefits to assuming that a beams with shorter notes
> will not be broken into larger groups beams with longer notes unless
> there is a specific rule requiring it.

Uh, your algorithm depends on this, right?

> I am less happy about having implicit rules being defined without any
> mention of it.  In the second example, there are implicit rules for
> 1/32, 1/64, and 1/128 beaming, but I can't see that from reading.  In
> the first example, all beams are explicitly covered.

But in the case of 2/2 timing, the current setting is
((* . (1 1)) ((1 . 32) . (8 8 8 8)))

If you don't want to revisit every rule whenever a new note duration is
added, * may only cover the shortest duration (under your algorithm's
assumption which I find reasonable).  So this would need to be
((* . (0.5 0.5)) ((1 . 8) . (4 4)) ((1 . 16) . (8 8 8 8)))

Which suffers from the slight problem that 0.5 (half a beat) is not even
an option in the * format.

> I think I would be in favor of eliminating *all* implicit rules, and
> having autobeams break only when they are asked for by some explicit
> rule.

And on the end of bar.

-- 
David Kastrup