Musical Definitions

A Score It is the representation of a whole music piece. A score could hold anything from a one bar music example, to a song, a piano sonata movement, or a movement of a symphony in full score. A work in more than one movement requires normally a different score instance for each movement.
It may have a title, one or more autors, and copyrights.

A Part A score can be splitted in several parts. Each part correspond to one performer, most of the time the performer is associated with one instrument. A stream of musical events can be extracted from this performer and design a Part. A part may contain music to be played sequentially on different instruments by the same performer (e.g. oboe/English horn). The maximum number of staves used for display is defined for each part. A part has a name that identify uniquely the part within the score. Parts have a predefined order for vertical placing in a complete score.

A Measure is the agregrate that contains attributes and notes for a part. Incidentaly, measure may contains several staves for a piano part for exemple but it may also contains none for a speaked movement for example. Attributes belonging to a measure are to help the representation but are not considered to be events. On a score the macro unit of time will be the measure, in the MusicXML it is a central concept. It has a time capacity settled by the current time signature (time signature never change into a measure with the exception of the simple time (3/4) to composite time or vice versa change (9/16)). Into a Measure are also constant the clef and the key signature. Voice separation is done in the measure unit.
So the lenght in terms of ticks of a measure is determined by its time signature.

A Measure Section help us to give a name to all the different parts' measure played at the same time. We so use Measure Section to only refer to Time Events

A Voice is a defined within a measure and it is a succession of Notes. The list of events of a voice are not recovering themselves by mean of time. Voice can never be in different part. In the program, we call voice a subset of the notes in a measure and in a part.

A Staff The staff is a decomposition of one instrument : It has been introduced for the piano and separating left hand and right hand. Staff identify the sequence of measures ordered by start time. The staff is an arrangement of parallel horizontal lines on sts parallel horizontal lines we can read the pitch of a music symbols. The staff isn’t a page layout related entity so cannot be hidden when few measures are muted as it cannot be shown when its measures contains noteheads.

A Tick or division is the time unit in the measure. To caracterize a Event we can use the start time in ticks in the measure. You can also use tick to caracterize duration of a measure.

A System It is the way the score will be presented. It must be understood as : system of representation. It is the visual framework on a page, where symbols representing simoultaneous events in the various parts are more or less vertically aligned. All parts of the score are logically present in every system although some may be hidden.The width of the system is based on the width of the page.It’s hortogonal to staves that brakes into staff chunk based on its width. To display a score as piano roll a page with infinite width is needed.

A Event An event is something which has a date of beginning. The point is that there is no duration fo an event.
It is the mechanism by which a specific point in time is identified in the score. Musical symbols representing simultaneous events are logically grouped within the same time-slice.
If an Event has a dsuration of 0 it put no constain on time, but it still has not to recover each other on a time slice. As a convention, every 0 duration event has to be considered at first before any other event.
The time point or tick is an int, it must be referred when knowing the time value of a tick

A Duration A duration is the lenght of a symbol Notes and Rests are concerned with this

A Note A note has a start time and a duration. A note can so also be a note.
A note in its conceptual design is not intended to have a stem. But it is necessary if we try to represent it.

A Event A rest is a note that does not produce any sound.

An Alteration modify slighly the pitch a note (either upper or lower)

A Grace note is a note that is played rapidly. In the musical representation, those note have no duration.

A annotation A annotation tells playing instructions

A TimeSignature A time signature contains every information for time in the measure : i.e

The Implicit alterations are when you do not remind a note is altered because a signature at the beginning of the line make this useless.

The Explicit alterations are when you remind or signal a note is altered.

A KeySignature Contains information for representing a given pich in the mesure. It contains information like the number of atleration it has. It could be represented with things like.C0, G1, D2, A3, E4, B5, F6

Section : A section is a set of successive measures having the same signature. There is two way of changing a signature in one case you start a new section. And in the other case you change the current section signature.

Object representation