Information Technology Reference
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format. The matter will be developed in Section
5, devoted to MX applications. At the moment,
in order to provide a broad picture, we underline
the possibility for the users to click any point of
the score and jump there also in the audio content
currently performed, as well as the possibility to
navigate the audio track moving a slider control
and highlight the related portion of the score.
Achieving the aforementioned goals implies:
(1) designing and adopting a suitable format to
represent music, (2) encoding music pieces and
all the related material in such format, and (3)
implementing software applications to achieve
synchronization and user interaction.
The first step is represented by the design of a
comprehensive representation format for music.
A formal and complete analysis of music richness
and complexity is provided by Haus and Longari
(2005), where six different levels of music descrip-
tion are identified—namely General, Structural,
Logical, Notational, Audio, and Performance
layers. This multilayer structure, suitable for our
concept of comprehensive description of music, is
reflected by the encoding format we will describe
in Section 4.
Here we are more interested in the reason why
XML and music make a good couple.
First, XML is a formal meta-language suit-
able for declarative representations. It is capable
to describe entities (in our case music objects)
as they are, without unnecessary information
overload. This kind of representation is modular
and hierarchical; nevertheless it allows explicit
interaction among modules. Internal relationships
are formal and explicit. All these aspects have an
important counterpart in music language, which
is formal and hierarchical too.
XML modularity can solve the problem of a
well-organized comprehensive description: each
part constitutes a separate plug of the overall
description, still maintaining its own identity.
However, interdependencies are allowed and made
explicit by an XML-based format.
Languages derived from XML are extensible,
as they support extensions and external entities.
This aspect is fundamental to take into account
further developments of music language or still
unforeseen uses of the description format.
Finally, XML is open to user contributions,
easy to be read, decoded, edited, and understood.
In principle, anyone can give suggestions and
implement specific parts of the format. Even if
easier than binary formats, XML in general is
not intended to be managed directly: rather, it
should be read and written by computer-based
systems. For instance, music XML cannot be
printed in its text form in order to be played at
first sight by a human performer; on the contrary,
we need specific software to decode the format
and represent it as a sequence of music symbols.
Fortunately, applications to edit XML files can
be easily found on the marketplace and usually
basic editors are free. Besides, specific software
able to work on a peculiar XML-based format
can be implemented without paying royalties or
licences, as most formats are free.
In conclusion, an XML-based language allows
inherent readability, extensibility, and durability.
A specific coverage of the matter is presented by
xml-Based representatIon of
musIc data and metadata
In the previous section, we have provided our
definition of “comprehensive description” applied
to music. In this sense, the inadequacy of current
file formats should be evident. As a satisfactory
standard is still unavailable, we propose some
guidelines to face the matter, introducing a new ap-
proach for computer-based music description.
A possible solution to the problem could reside
in the adoption of an XML-based format. There are
many advantages in choosing XML
1
to describe
information in general, and music information in
particular. Many texts and scientific papers have
already described the advantages of XML-based
formats applied to information representation.
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