Historically, the ChordPro file format was defined solely by the behaviour of the program implementating it: the
chord program by Martin Leclerc and Mario Dorion. That was 25 years ago. Since then the easy to use file format was adopted and extended by many implementations. For practical reasons, this is called ChordPro version 4. Its latest reference implementation is an updated version of the old
chord program called Chordii.
ChordPro version 5 is designed from the ground up, using version 4 and several alternative implementations as a starting point. With version 5, a brand new reference implementation was written by Johan Vromans: ChordPro. This program provides support for ChordPro version 5, but it also supports most of the features of Chordii, and a lot more.
While PostScript was a good choice 25 years ago, nowadays PDF is much better. Not only for printing, but also for viewing on PCs, phones, tablets and so on. ChordPro produces PDF documents natively, i.e., without the help of 3rd party tools.
chord program was already revolutionary in supporting the ISO-8859.1 character set for input, allowing most european languages to be processed. ChordPro takes all input in UTF-8 encoded UNICODE but falls back to ISO-8859.1 if needed. When the input files contain a Byte Order Mark, UTF-16 and UTF-32 are also handled automatically.
Note that the default fonts that ChordPro uses only have limited support for non-Latin1 characters. If you need more extensive Unicode support, you must configure ChordPro to use TrueType or OpenType fonts that have sufficient Unicode support.
Originally developed for guitar players,
chord was hard coded to support 6-string instruments. This frustrated mandolin, banjo and ukulele players. ChordPro lifts this limitation and allows an arbitrary number of strings.
Often asked for, and ChordPro finally got it: Nashville Numbering and Roman Numbering of chords.
Using configuration files you can not just change fonts and sizes, but you get total control over the appearance of the output. Margins, headers, footers, columns, and more.
While this may be considered a feature, it is in fact a necessity since most basic fonts do not have sufficient support for UNICODE.
Traditionally a command line program,
chord was not a trivial tool for users of Windows based systems. ChordPro adds WxChordPro, a GUI version of the program.
There are just a few features that ChordPro does not, and will not, support:
The notion of ‘easy’ and ‘hard’ chords.
The chord directive can be used if you want diagrams for specific chords.
Logical pages, i.e. 2-up and 4-up printing.
PDF viewers and print tools can do that for you.