ChordsDescriptors¶

Inputs¶

• chords (vector_string) - the chord progression

• key (string) - the key of the whole song, from A to G

• scale (string) - the scale of the whole song (major or minor)

Outputs¶

• chordsHistogram (vector_real) - the normalized histogram of chords

• chordsNumberRate (real) - the ratio of different chords from the total number of chords in the progression

• chordsChangesRate (real) - the rate at which chords change in the progression

• chordsKey (string) - the most frequent chord of the progression

• chordsScale (string) - the scale of the most frequent chord of the progression (either ‘major’ or ‘minor’)

Description¶

Given a chord progression this algorithm describes it by means of key, scale, histogram, and rate of change. Note:

• chordsHistogram indexes follow the circle of fifths order, while being shifted to the input key and scale

• key and scale are taken from the most frequent chord. In the case where multiple chords are equally frequent, the chord is hierarchically chosen from the circle of fifths.

• chords should follow this name convention <A-G>[<#/b><m>] (i.e. C, C# or C#m are valid chords). Chord names not fitting this convention will throw an exception.

Input chords vector may not be empty, otherwise an exception is thrown.

References:

[1] Chord progression - Wikipedia, the free encyclopedia, http://en.wikipedia.org/wiki/Chord_progression

[2] Circle of fifths - Wikipedia, the free encyclopedia, http://en.wikipedia.org/wiki/Circle_of_fifths

Source code¶

• C++ source code

• C++ header file

See also¶

ChordsDescriptors (streaming) Histogram (standard) Histogram (streaming)