narcispr / ChordProgressions

SongHarmony is an API for describing the harmony of a song and render it in SVG.

ChordProgressions

ChordProgressions is an API for describing the chord progression of a song using XML and render it in SVG and PNG.

It can include:

• Chord root (C, Eb, F#, ...)
• Chord species (-, -7, Maj7, 6, ...)
• Keys (C Major, A minor, ...)
• Grades per chord (I, ii, iii, IV, V, vi, vii°, ...)
• V --> I and ii --> V symbols (arrows and claudators, solid or dashed)
• Sections (A, B, ...)
• Repeat signs (firs ending, second ending, ...)
• Used scales on the chord (Ionian, Dorian, Pentatonic ...)

Syntax

The main tag in any chord progression is <song>. It can include the following tags:`

• <title>,
• <composer>, and
• a list of <measures>.

Additionally, it can include also formatting tags like:

• <measures_per_line>, or
• <chords_per_measure>.

The <measures> tag can include as many <measure> tags as required and each <measure> tag may include:

• a list of <chord> tags,
• <section>,
• <init_bar>, <end_bar> or <repeat_bar> tag to indicate which bar separation must be included, as well as
• <first_end> or <second_end> tags to include these special symbols.

Finally, every <chord> tag includes:

• <root>,
• <specie>, and optionally
• <grade>,
• <new_key>,
• <ii_bracket>, <subii_bracket>, <v_i_arrow> or <subv_i_arrow> standard harmony analysis symbols and
• <scale>.

Example

You can see how the popular song Summertime is codified in XML using ChordProgressions here]. The XML file is rendered to SVG and PNG using:

python3 render_chord_progression.py XML_songs/summertime.xml 1.5

and the result looks like this:

Code created by Narcís Palomeras