### Chordal Analysis

*xmlChordAna* is a python script that makes a chordal analysis of a MusicXML file.

An [interactive demo][1] is avaiable on the

[Chord Analysis][1] page. It runs the script on

my server and formats the output in some neat html.

At the command line *xmlChordAna* is used as follows:

        > ./xmlChordAna.py scorefile.xml

The output is printed in plain text looks like this:

        File: bwv539p_arr.xml, ticks per quarternote: 384

        342 note groups, 102 chord segments

        Key: Am, confidence: 33%

        ---- chord Dmin, score: 90%

           0     D3, D4, F4, A4

           2     D3, F4, A4, D5

           2 1/2 F4, A4, D5, D3

           3     F4, A4, D5, C#3

           3 1/2 F4, A4, D5, D3

        ---- chord Ehdim, score: 75%

           4     D5, E3, E4, G4

        ---- chord C#hdim, score: 92%

           5     E3, E4, G4, C#5

           5 1/2 E3, E4, G4, B4

           6     E3, E4, G4, C#5

           6 1/2 E4, G4, C#5, E3

           7     E4, G4, C#5, D3

           7 1/2 E4, G4, C#5, E3

        ...

See [this explanation](https://wim.vree.org/keys09/uitleg.html) for more info.

### KeyScape

On the [KeyScape](../keys09) page you can find two other interactive demos. One makes

a *keyscape* from a MIDI file. The other runs the same chordal analysis as *xmlChordAna*,

but for a MIDI file. There is no download page (yet) for these programs.

### Base-40 note numbers

*xml2b40* is a python script to convert a MusicXML file to a list of base-40 events.

It is invoked from the command line as follows:

        > ./xml2b40.py -t 384 scorefile.xml

and produces the following output:

        0 129

        0 169

        0 180

        0 192

        768 -192

        768 -169

        768 192

        768 209

        960 -129

        960 129

        1152 -129

        1152 124

        1344 -124

        1344 129

        1536 -192

        1536 -180

        ...

Each line contains two numbers: the time and a base-40 note.

The time is in ticks, where a quarter note is 384 ticks. The base-40 note number is positive

when the note starts sounding and negative when the note stops sounding.

The base-40 note number system encodes 40 pitches in an octave.

It is maps all single and double accidentals.

For instance, the first 10 numbers are:

        1:  Cbb

        2:  Cb

        3:  C

        4:  C#

        5:  C##

        6:  not used 

        7:  Dbb

        8:  Db

        9:  D

        10: D#

Base-40 numbers allow precise matching of chord patterns. For instance, chord pattern

C7 only matches

C-E-Bb and not C-E-A# or C-Fb-Bb or B#-E-Bb etc.

The idea of base-40 note numbers is due to B. Hewlett and described in

[this paper][2]

[1]: ../keys09/abc2chord.html?../js/pre_wind.js

[2]: http://www.ccarh.org/publications/reprints/base40/