Information Technology Reference
In-Depth Information
As with the previous cases of transformations, the above example assumed a
maximal fMRI_index value, but the effect of the transformation can be mediated by
reducing the value of the fMRI_index. This is illustrated in the following example.
Let us assume the case of fMRI_index = 2. This gives a CS value of 0.3. With
such a low value for the control signal, we should expect only a small amount of
pitch delta transformation.
As before, we will use the input signal shown in Fig.
12.14
, this time with the
transformed values from the full pitch delta transformation shown in Fig.
12.19
,to
the difference
d
, as follows:
d ¼ 71
71
f
ð
Þ;
71
71
ð
Þ;
77
74
ð
Þ;
76
72
ð
Þ;
73
71
ð
Þ
g
d ¼ 0
;
0
;
3
;
4
;
2
f
g
er values are then calculated by multiplying the difference
values by the CS value, which is equal to 0.3:
The scaled modi
SMV ¼ 0
0
:
3
f
ð
Þ;
0
0
:
3
ð
Þ;
3
0
:
3
ð
Þ;
4
0
:
3
ð
Þ;
2
0
:
3
ð
Þ
g
SMV ¼ 0
;
0
;
0
:
9
;
1
:
2
;
0
:
6
f
g
Finally,
the SMV values are summed to the original
input
to give a new
sequence of pitch values:
New pitches ¼ 71
þ
0
f
ð
Þ;
71
þ
0
ð
Þ;
74
þ
0
:
9
ð
Þ;
72
þ
1
:
2
ð
Þ;
71
þ
0
:
6
ð
Þ
g
New pitches ¼ 71
;
71
;
74
:
9
;
73
:
2
;
71
:
6
f
g
As with the previous transformation examples, pitch values are rounded up to
the nearest whole number, giving a transformed sequence of pitch values of {71,
71, 75, 73, 72}, which is rendered as {B4, B4, D#5, C#5, C5}, as shown in
Fig.
12.20
. The exaggerating effect of the pitch delta has been radically mediated by
the value of CS, with a much smaller amount of change seen in the transformed
output than in the full pitch delta transformation shown in Fig.
12.19
.
The generative potential of a composition system that incorporates transforma-
tive processes, such as that offered by MusEng, is high.
Fig. 12.20
Transformed output created by pitch delta algorithm with a relatively low
fMRI_index value of 3
