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Transcript
Presentation
Automatic Pitch Spelling
From Numbers to Sharps and Flats
Emilios Cambouropoulos
Xiaodan Wu
Feb.12 2003
About the author
Emilios Cambouropoulos completed his PhD thesis on
Music and Artificial Intelligence at the University of
Edinburgh.
Till February 1999, he worked as a research associate at
King's College London on a musical data-retrieval
project: Musical Similarity and Melodic Recognition.
Currently, he is working as a research fellow at the
Austrian Research Institute for Artificial Intelligence on
the project: Artificial Intelligence Models of Musical
Expression.
Publication we are going to study:
•The Local Boundary Detection Model (LBDM) and its Application in the Study of
Expressive Timing
• From MIDI to Traditional Musical Notation
What’s the challenge?



An example from the pitch
representation in MIDI and
its alternative spelling
It’s polyphonic
No prior knowledge such as
 Key signature
 Tonal centers
 Time signature
 Voice separation
60 Midi Pitch
Dbb
|
C
|
B#
Alternative spelling
The previous works
Researcher
Algorithm features Common points
Cambouropoulos  Avoids diminished,
augmented and chromatic
1996
intervals
Only for monophonic
pitch sequences

Temperley
1997
 Avoids
doublesharps and double Spells pitches so that as
flats
close as possible together
on the “line of fifths”
 Can be applied to
polyphonic pitch
sequences
The pitch spelling algorithm



The input to the algorithm is a list of MIDI pitch
values
The optimization procedure relies on two
fundamental principles:
 Notational Parsimony
 Interval Optimization
Penalty values are introduced.
The pitch spelling algorithm
continue
Distance 1
2
3
Intervals 4P 2M 3m
5P 7m 6M
Class
A
Intervals 4P 2M 3m
5P 7m 6M
4
5
6
7
8
9
10
11
12
3M
6m
2m
7M
4a
5d
1a
1d
4d
5a
2a
7d
3d
6a
3a
6d
2d
7a
B
C
3M
6m
2m
7M
2a
7d
3d
6a
D
4d
5a
4a
5d
1a
1d
3a
6d
2d
7a
The pitch spelling algorithm
continue
Penalty Values:

Notational Parsimony
‘normal’ spelling of note
enharmonic spelling of note

0
4
Interval Optimization
Class A or B
Class C
ClassD
0
1
3
For each spelled pitch sequence, all the penalty values for
every possible intervals are summed. And the sequence with
the lowest penalty value is selected.
The pitch spelling algorithm
continue


A shifting overlapping windowing
technique is hired to pick up certain
sequence for spelling pitches
The length of the window could be
modified.
The Result
Experiment 1
Total # of
notes
Notes with
accidentals
40058
10900
Misspelled
notes
649
Correct
Spelling
94%
Experiment 2
Total # of
notes
Notes with
accidentals
40058
10900
Misspelled
notes
501
Correct
Spelling
95.4%
Experiment 3
Total # of
notes
40058
Notes with
accidentals
10900
Misspelled
notes
424
Correct
Spelling
96.2%
The drawback



There is a trade-off for the different pitch interval
orderings.
The technique to select the length for the window.
Voice-leading concerns are not currently
considered.