Digital Signal Processing Reference
In-Depth Information
Table 11.16
Distribution of
the keys and chords in the
ChoRD database
Root
# Key
# Major
# Minor
# Other
A
7
511
459
57
A#
8
567
171
86
B
7
480
213
61
C
16
854
278
105
C#
5
312
315
61
D
3
557
349
94
D#
8
533
141
61
E
12
643
362
21
F
13
728
272
52
F#
4
407
209
44
G
12
719
287
103
G#
5
353
196
41
Sum
100
6 664
3 252
786
To provide sufficient data for machine learning and testing, a total of 100 musi-
cal pieces—a representative variation of typically aired pop and rock music—was
annotated with the tempo in BPM, the key, and each chord based on original scores
as ground truth reference by three experienced musicians. The set contains 64 dif-
ferent artists, and on average, 1.6 pieces per artist. 18 artists are found more than
once in the set: five songs are contained of each of Delta Goodrem, James Blunt, and
Robbie Williams, followed by four songs, each, of Celine Dion, Coldplay, and Enya,
three songs, each, of Bon Jovi, Bryan Adams, Cher, and finally two songs, each, of
All Saints, Backstreet Boys, Britney Spears, Keane, Phil Collins, Roxette, and The
Corrs.
All pieces have constant tempo. The complete list of songs is available for down-
load.
4
The original recordings were compressed to 128 kbit/s MP3, and the total
playtime is 6 h 58 min 12 s. 10702 bars are contained overall. The seven chord types
annotated are major, minor, suspended second or fourth, augmented, diminished,
and 'power chords'—i.e., the typical combinations of root and fifth with second,
third, fourth or no further interval. Rather than seven chord types times 12 notes only
6
76 final chord classes were obtained, as only four different augmented
chords exist. Due to sparseness of certain types, cover classes were used as follows: 36
major / minor / other chords (where other chords are augmented, diminished, power,
and suspended), and 24 major / minor chords. The total of chord instances was kept
constant throughout mapping by mapping according to the root and musical function
in the context such as “Cno3” (“C” as power chord, i.e., without a third) onto “C” if
the piece is in the key of C major or onto “Cm” if the piece is in the key of A major.
Table
11.16
shows the frequencies of keys and chords within the ChoRD database
by root note for the classes major, minor, and others.
·
12
+
4
=
4
