Information Technology Reference
In-Depth Information
Table 12.3
Musicodes for the
first two measures of the musical sequence in Fig.
12.10
1
2
3
4
5
6
7
8
9
Melody direction
0
−
1
+1
−
1
0
+1
+1
−
1
−
1
Melody interval
0
5
2
4
0
1
1
1
1
Event duration
120
120
120
120
60
60
120
60
60
Note pitch
E5
G#4
B5
E4
B5
C5
D5
C5
B5
A min
C Maj
The rows correspond to the event number or, in this case, number of notes in the sequence: the first
two measures comprise a total of 9 notes
Modality
E Maj
A harmonic min
Fig. 12.10
An example of a musical sequence
Pitches of the notes
Melody directions between successive notes in a sequence
Melody intervals, i.e. the amount of change between the pitches of successive
notes in a sequence
Note durations
Modalities implied by groups of notes in a sequence
These features are stored as event-based vectors, referred to as
musicodes
.
Table
12.3
shows the musicodes for the
first two measures of the musical excerpt
shown in Fig.
12.10
.
Melody direction can be
1, 0, or +1, referring to descending, motionless or
ascending movement. The current note in a sequence is compared with the previous
note; the very
−
first note in a sequence therefore returns a value equal to 0. Melody
intervals are represented in terms of half steps, which are also calculated with
reference to the current note
rst note
in the sequence returns a value equal to 0. With note durations, the value 240 is
assigned to quarter notes, and other durations are calculated with reference to this
value; for example, half notes are equal to 480 and eighth notes are equal to 120.
Values for pitches are readily extracted directly from the corresponding MIDI code,
for instance, MIDI 21 = Note A0, MIDI 23 = Note B0, MIDI 24 = Note C1 and so
on.
'
s distance from the previous note. Again, the
2 is used to represent the absence of data in a musicode
vector. Thus, the note pitch musicode for a musical rest would be equal to
−
2. With
respect to the implied modality of segments, the system creates a label specifying a
tonal pattern and indicates when the estimation is ambiguous. For example, in the
In general, the number
−
first measure of the music shown in Fig.
12.10
, the system sees E, G# and B, as an
E Major chord, but the G# has also implied A harmonic minor.
