Music Encoding Initiative (MEI) DTD and the OCVE

Perry RolandDigital Library Research & Development Group, Alderman Library, University of Virginiapdr4h@virginia.eduhttp://www.people.virginia.edu/~pdr4h

Purposes of the DTD

encoding interchange

Encoding

not necessarily an input code, but still human readable (and understandable!)

declarative – preferable to procedural representation formal – verifiable explicit – context independent flexible – allows selective feature encoding, can be

constrained, separates visual, gestural, and analytical domains

extensible – for unknown uses, future development of particular interest: musical form, text, critical apparatus

Interchange

comprehensive – generalized software independent N*(N-1) vs. N*2 translators

30 translators 12 translators

MEI

<!ELEMENT mei (meihead, work)><!ELEMENT meicorpus (meihead, mei+)><!ELEMENT meihead (meiid, filedesc, projectdesc?, editorialdecl?, profiledesc?, revisiondesc?, sourcedesc*)><!ELEMENT work (front?, (music|group), back?)><!ELEMENT group ((work|group), (work|group)*)><!ELEMENT music (mdiv+)><!ELEMENT mdiv (score?, parts?)><!ELEMENT score (div*, (section, ending*, div*)* | (measure?, (pb|sb)?)*)><!ELEMENT parts (part)+><!ELEMENT part (div*, (section, ending*, div*)* | (measure?, (pb|sb)?)*)><!ELEMENT section (div*, (section, ending*, div*)* | (measure?, (pb|sb)?)* | staff* | app*)><!ELEMENT app (rdg, rdg+)><!ELEMENT rdg (div*, (section, ending*, div*)* | (measure?,(pb|sb)?)* | staff* | app*)><!ELEMENT ending (div*, (section, ending*, div*)* | (measure?,(pb|sb)?)* | staff* | app*)><!ELEMENT measure (((staff* | (beam | beatrpt | btrem | chord | ftrem | note | pad | rest | space | tuplet)* | layer* | (msrest | msrpt | multirest | multirpt)?)), ossia*, (annot | arpeg | beam2 | bend | dir | dynam | gliss | hairpin | harm | lyrics | midi | mordent | octave | pedal | phrase | reh | slur | tempo | tie | trill | turn)*, (curve | line | symbol )*)>

Basic MEI DTD

Document element

mei (meihead, work) – encodes a single work separates document into data and meta-data parts,

allowing meta-data to be shared with other internal and external entities

name cannot be changed in order to assure an absolute minimum level of MEI compliance

Alternate document element

meicorpus (meihead, mei+) – encodes multiple mei instances where each requires a header of its own

also provides header for entire file name cannot be changed in order to assure an

absolute minimum level of MEI compliance

meihead element

encodes bibliographic (descriptive, administrative, and technical) meta-data for the file

filedesc element contains data, such as title, agent, and publication status, and access data, such as vendor, price, and rights management info, for the file

sourcedesc element contains descriptions of each source for the file. source elements employ the same bibliographic elements as filedesc, but also include physical description elements, such as medium, dimensions, provenance, inscription, condition, etc.

work element

the "thing" being encoded may include not just music notation, but also the

textual matter often found in a critical or historical edition, composer's textual notes, advertisements, etc.

name cannot be changed in order to assure an absolute minimum level of MEI compliance

Work-level text

front and back child elements provide basic logical and presentational text markup functionality

accommodating text gives control of the text and notation to MEI, which embedding notation in another markup scheme, such as TEI, will not do

music element

encodes the musical, as opposed to the textual, content of the work

contains highest-level indication of the structure of the composition – one or more discrete, linear segments, called mdiv ("musical division")

generic mdiv elements may be typed – symphonies, for example, usually consist of movements while operas are made up of acts

group element

facilitates creation of a collection of work elements that share a bibliographic header – a collection of songs by different composers issued under a single title, for example

basic meta-data for each work may be encoded in its own front matter or in source elements in the file header

use meicorpus element when a complete bibliographic header is required for each member of a collection

mdiv element

may contain one or both of two possible organizing views – score and parts

score element contains a time-oriented view of the composition – a full score

parts element contains part elements each of which represents a performer's view

mdiv element, con't.

score and parts views are intended to accommodate different methods of organizing the markup – no particular presentation is implied, software may render a collection of parts as a score or a score as a collection of parts

it is not always possible or desirable to generate one view from the other. A great deal of complexity can be eliminated by separating score and part markup.

part element

has all the encoding features of a full score – content models of score and part elements are identical

voice-leading should be recorded at the event level using the next or prev attributes

part element, cont.

use part elements when

– there is no score, only a collection of parts– parts don't share visual characteristics, such as typeface or

layout with the full score or with each other– score has non-aligning bar lines– accommodating rendering software that requires staff-by-staff

encoding

section element

score or part may be divided into linear segments or sections sections usually function as scoping mechanisms for clef signs,

key and meter signatures, and expression marks minimize the need for backward scanning to establish context

when the starting point for access is not at the beginning when a section contains sections, the expan attribute on the

outer section element may be used to encode the performance order of the inner sections

section element, con't.

may also be used for user-defined, that is, analytical or editorial, purposes

may be arbitrarily nested to any level

app and ossia elements

an app element contains at least one alternative reading

each rdg may be linked to a source description in the header

rdg may contain app so that variants of variants may be described

each rdg may be assigned an order, e.g. for selection or rendering purposes, other than the encoded order

ossia performs a similar function at the measure level, however, it represents an alternative present in the source being transcribed.

ending element

specialized form of the section element that may not be recursively nested

<section expan="a b a c">

<section id="a">

<measure>...</measure>

</section>

<ending id="b" label="1.">

<measure>...</measure>

</ending>

<ending id="c" label="2.">

<measure>...</measure>

</ending>

...

</section>

measure element

contains events, not symbols even though events have visual properties, modeling

symbols places too much emphasis on presentation and makes the markup less useful as a general "music" (as opposed to "notation") markup scheme

is a linking element that connects the MEI document to an external electronic object, i.e., image, or to another location within the current MEI instance

Control events

control events, such as dynamics, ties, phrase marks, pedal marks, etc. depend on other events

do not fit the principal hierarchy of sections, measures and staves

multiple control events of the same type, i.e., pedal indications, may be associated with the same set of events, i.e., notes

staff element

may be used to indicate division of the measure's contents into multiple data streams

<measure> <staff def="1"><note /><rest />...</staff> <staff def="2"><note /></staff> </measure> does not necessarily indicate layout! in a staff-by-staff encoding, staff may contain measure elements <staff> <measure n="1">...</measure> <measure n="2">...</measure> </staff> <staff> <measure n="1">...</measure> <measure n="2">...</measure> </staff>

Music Encoding Initiative (MEI) DTD and the OCVE

Perry RolandDigital Library Research & Development Group, Alderman Library, University of Virginiapdr4h@virginia.eduhttp://www.people.virginia.edu/~pdr4h