[MEI-L] Music Addressability API draft

[Craig Sapp]

Hi Perry,

On 12 November 2014 02:49, Roland, Perry D. (pdr4h) <
pdr4h at eservices.virginia.edu> wrote:

> Point 2:
> I'm not opposed to somehow allowing fractions within data.BEAT, but if we
> make our position on Point 1 clear, then I don't see the need for it, since
> "1.3" is just another way of writing "1+1/3".
>

Is that how math works in WV?  How would I know that, and what do 1.1, 1.2,
1.4, 1.6, 1.7, 1.8 and 1.9 mean?


> I don't think we should be concerned with round-off error since the
> decimal part of "1.3" is intended to indicate a fractional part of the
> beat; that is, one can write "1.333" or "1.3" or "1+1/3", but all three
> mean the location of the 2nd note of a triplet beginning on beat 1, in
> other words, a musical value, not a visual one.  @tstamp2 *should only*
> refer to the "logical" endpoint. @ho should be used to move the visual
> endpoint.  This contradicts my own earlier thinking and Johannes'
> suggestion to use "4.999" to encode a hairpin stopping just before the
> beat.  I believe this erroneously conflates the logical and visual
> endpoints.
>

The problem is: what is the visual syntax hairpin endings?  Should it be
inclusive and/or exclusive of the timestamp value?  And how does this
interact with barlines?  The main issue is how a hairpin crescendo behaves
at system breaks.  If an endpoint is exactly on a beat, then how can the
endpoint be in reference to a barline as opposed to the next note after the
barline (or grace notes before the beat, which is another matter)?  If the
endpoint refers to the note, then applying a horizontal spatial offset will
not solve the problem of having a little tiny piece of the crescendo after
the system break, as it will be offset from that note onto the new line.
Giving an offset of "4.999" solves the ambiguity by forcing it to stop
before the barline and hence the system break.  But the problem is what to
do when the music changes layout and different hairpins pop up with the
same problem.

By the way, "4.999" for hairpins would be acceptable to me :-) I was mostly
referring to note/rest durations.  Dynamics and hairpins and such do not
need to be as strictly regulated since their interpretation can be fuzzy,
and they are attached to the main framework of the note durations rather
than define the rhythmic framework themselves.  Adjustments to the behavior
of the hairpin endpoint should probably not be controlled by this value,
but by some other parameter, such as having the default mean stop at the
barline before any note with this timestamp, and then have an option to
specify that the endpoint refers explicitly to a note and not the barline
preceding it.

Put into a graphical illustration for people whose eyes have already glazed
over, how would/should these cases be handled?:


​
* How could each of these hairpins be represented in MEI?
* How can the barline and the note that follow it be disambiguated from the
timestamp?

When a hairpin ends on a barline, it must have an offset by default to get
it from actually ending on the barline (at least when the barlines would
touch it as in the above example).

Also imagine grace note(s) before the first note in each measure.  If the
hairpin ending point is a timestamp, then which graphic object does it
refer to:(1) the barline, (2) the grace note(s), or (3) the note?

Another question illustrated in the example (and relating to
addressability) is how to reference positions of noteheads.  Suppose that I
want to end hairpins on the right side of note heads?  If I use virtual
units, those virtual units would be in reference to a specific notehead
shape (font).  Germans like oval noteheads while Italians like circular
ones...  It is a bit picayune (vocab builder word for ESLs), but
occasionally I have a desire to do that in SCORE, which does not have that
capability so I have to fudge it by zooming in and manually adjusting.

-=+Craig
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