[MEI-L] Beat in 6/8

Thu Aug 27 10:19:57 CEST 2015

Hi all,

many thanks for bringing up this interesting discussion, I was not aware 
that the definition of "beats" was so uncertain throughout music 
history! Nevertheless I think that in MEI the definition of beat is very 
clear.

If we consider http://music-encoding.org/documentation/2.1.1/cmn/ and 
the description of the following scoreDef attributes (4.1.2 Defining 
Score Parameters for CMN):

>
> meter.count 	captures the number of beats in a measure, that is, the 
> top number of the meter signature. It must contain a decimal number or 
> an additive expression that evaluates to a decimal number, such as 2+3.
> meter.unit 	contains the number indicating the beat unit, that is, the 
> bottom number of the meter signature.
>

and further the description of timestamps (4.1.5 Timestamps and Durations):

> Thetimestamp(tstamp) of a musical event is calculated in relation to 
> the meter of the current measure and resembles the so-called ‘beat’. 
> In a common time measure with four quarter notes, the timestamp of 
> each quarter equals its beat position in the measure: The first 
> quarter has a timestamp of 1, the second has a timestamp of 2, and so on.

If we then consider 4.2.9 Repetition in CMN the descrition of beatRpt 
might be a bit confusing, as the only definition of the "logical domain" 
implication is the first sentence:

> ThebeatRpt 
> <http://music-encoding.org/documentation/2.1.1/beatRpt>element is used 
> to represent a single repeated beat.

All the rest of the paragraph deals with "visual domain" aspects 
exclusively:

> Its visual rendition can be recorded using therendattribute. This 
> attribute indicates the number of slashes required to render the 
> appropriate repeat symbol, which, as demonstrated in the preceding 
> figure, depends on the rhythmic content of the beat being repeated. 
> When a beat that consists of a single note or chord is repeated, the 
> repetition sign is typically rendered as a single thick, slanting 
> slash; therefore, the value '1' should be used. The following values 
> should be used when the beat is divided into even notes: 4ths or 
> 8ths=1, 16ths=2, 32nds=3, 64ths=4, 128ths=5. When the beat is 
> comprised of mixed duration values, the symbol is always rendered as 2 
> slashes and 2 dots.

So to summarize:
A beatRpt always repeats a timespan with a duration according to the 
"locally valid" scoreDef/@meter.unit.

At least that's how I understand it, an how we used it in Freischütz 
Digital ;-)

Cheers,
Benjamin

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Am 27.08.2015 um 01:08 schrieb Eleanor Selfridge-Field:
> To pick up threads from Don's and Laurent's posts, the main reason MuseData allows a double representation in certain rhythmic situations is precisely because in eighteenth-century music the logic of written notation and the logic of sound-oriented files such as MIDI simply do not coincide.
>
> Some instructive instances occur in Corelli--e.g. in movements in compound meter (6/8, 12/8), where active parts such as violins maintain a running series of eighth notes grouped conventionally by threes, but the accompanying bass parts are notated in C (common time) and the units are undotted quarter notes.
>
> In Bach, a common situation involves a beamed group consisting of a dotted quarter followed by three (or five) thirty-seconds (i.e., non-binary subdivisions).  The values in performances are subject to interpretation.
>
> In short, it does not take an irregular meter to produce irregular groupings or "illegal" polyphonic alignments.
>
> Eleanor
>
> Eleanor Selfridge-Field
> Consulting Professor, Music
> Stanford University
> Stanford, CA 94305-3076, USA
> esfield at stanford.edu <mailto:esfield at stanford.edu>
> Profile: https://profiles.stanford.edu/eleanor-selfridge-field
>
>
> -----Original Message-----
> From: mei-l [mailto:mei-l-bounces at lists.uni-paderborn.de] On Behalf Of Byrd, Donald A.
> Sent: Wednesday, August 26, 2015 7:03 AM
> To: Music Encoding Initiative
> Subject: Re: [MEI-L] Beat in 6/8
>
> Executive summary: In 6/8 specifically, I think it should be a dotted quarter, not an eighth. Now some discussion of the issues:
>
> I think most of us would agree that whether the beat is an 8th or a dotted quarter in 6/8 (or 9/8, 12/8, etc.) depends mostly on the tempo, but I doubt if we want to infer that from metronome marks, much less verbal tempo indications! FWIW, I'd guess the dotted-quarter beat is more common.
>
> Of course the same question arises in compound meters with denominators other than 8. Is the beat in 9/16 a 16th or a dotted 8th? It even worse in irregular meters. In 5/8, a measure might have five beats of an 8th each, or a quarter followed by a dotted quarter, or a dotted quarter followed by a quarter!
>
> But in _Behind Bars_, p. 230, Gould solves the problem in terms of notation with the rule that a single diagonal line means to repeat the previous beamed group of total duration of a quarter (or dotted quarter), two diagonal lines a duration of an 8th (or dotted 8th),  three diagonal lines a duration of… You get the idea. So, while she calls these beat repeats, she defines them in terms of beaming! But of course she's talking about usage for new scores,  not what appears in Weber or Beethoven or whever's manuscripts!
>
> --Don
>    
>
> On Aug 26, 2015, at 2:22 AM, Laurent Pugin <lxpugin at gmail.com> wrote:
>
>> Hi,
>>
>> I am looking at beat repeats (<beatRpt>) and I am not sure how to deal with them in 6/8 (or 9/8, etc). Defining the beat in 6/8 is a recurrent issue. Looking at timestamps, it seems that each 8th has to be considered as a beat. But in the beatRpt examples in the guidelines it seems that a 4.th is considered as a beat.
>>
>> Considering that the number of slashes have to be encoded in the @rend attribute, rendering the beat repeats properly is not that much of an issue because we could just ignore the beat duration and just display the dashes. (Only rendering repeats of mixed duration values would be an issue since it is not clear how this has to be encoded.) However, this would not work if we need to align them with other voices, for example. Any recommendation on this particular issue (<beatRpt>) and on how to consider beats in 6/8 in general?
>>
>> Best,
>> Laurent
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> ---
> Donald Byrd
> Woodrow Wilson Indiana Teaching Fellow
> Adjunct Associate Professor of Informatics Visiting Scientist, Research Technologies Indiana University Bloomington
>
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