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thus allowing an integrated and evolved enjoy-
ment of music contents.
Before describing the second application aimed
at user interaction with music contents, some
words on real-time synchronization among MX
layers must be spent. In MX, some layers contain
only the concept of
relative time
, some others have
also the idea of
absolute time
, and layers such as
General do not have a time concept at all. The
relative time
concept resembles the execution
of a music score: even if the score presents its
own internal temporal relationships, in absolute
terms music can be performed slowly or quickly.
Similarly, the spine of an MX file contains an
internal temporization, not in absolute terms
(such as seconds) but in relative terms: each event
is related to the previous one through a relative
time and space distance. The main layer present-
ing this form of time specification is Logic layer.
LOS, Notational, and Structural layers inherit this
behavior, as their time parameters are specified
only in function of the spine. On the other hand,
the concept of
absolute time
is present in Perfor-
mance and Audio layers. Here, in addition to spine
links, the events must have an absolute timing
associated (expressed either in seconds, ticks, or
frames, depending on the file format). The absolute
timing lets the application determine the precise
time occurrence of a given event within the clip.
In this way, when an audio/video file is played,
the relative time specifications of the spine are
translated to absolute timings. This mechanism
allows association of different performances (with
different absolute time values) to the same logical
representation (where events are characterized by
relative time relationships).
In summary, a symbolic score contains only
relative timing indications (rhythmical values,
vertical overlaps), but our mapping lets us associ-
ate different performances of a piece to a single
spine along with their different agogics. As a
consequence, the real-time execution of an MX
file is possible only in two cases: (1) by specifying
a relative/absolute time ratio, or (2) by running
one and only one associated performance/clip. In
fact, multiple simultaneous performances/clips
would actualize in different ways the concept of
relative time, and this would represent a prob-
lematic issue.
In MX Jazz Demo, our approach follows the
latter method. As a consequence, when
play
com-
mand is activated in a performance/clip window,
previously running files are stopped. This is the
only case of non-concurrent execution: all the
linked objects from all the other layers can be
shown at the same time and kept synchronized.
On the contrary, a file containing a temporized
performance (e.g., a MIDI file) cannot be played
during the execution of another audio or video
file (e.g., an MP3 file).
The second MX demo aimed at music enjoy-
ment was installed at the exhibition “Tema con
Variazioni. Musica e innovazione tecnologica”
(Theme with variations. Music and technologi-
cal innovation), a voyage into the Italian musical
heritage through the rooms held at Rome's Music
Park Auditorium in December 2005. All the im-
ages shown are courtesy of Italian publishing
house Ricordi
9
, which owns the manuscripts of
the most important Italian composers of the last
two centuries.
One of the purposes of the exhibition was mak-
ing music tangible and visible bringing together
the five senses, not just hearing. In this context we
have designed a simple user interface, conceived
for untrained people, in order to listen to and
visualize a track alongside variously interpreted
scores. This application, entitled MX Navigator,
represents the natural evolution of MX Jazz Demo.
The main differences between MX Jazz Demo
and MX Navigator are the following two:
•
The latter is a generalized version of the
former, as MX Jazz Demo was designed only
to demonstrate MX format characteristics
and worked on the limited number of pieces
consequently chosen, whereas MX Naviga-
tor is virtually able to open any MX file. In
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