For all chants a midi file is provided.
The purpose of these midi files is two-fold. In the first place they can be used to check whether the chant is actually the one you are looking for. Secondly, they can be used to search for a new chant for a specific circumstance (e.g. a given key). In that case one can scroll through the list and listen to which one seems fit for the situation.
It would have been sufficient (in most cases) to provide for one midi file for each fingerprint.
However, occasionally two chants (by the same or by a different composer) that are different may have the same fingerprint, so it helps if each occurence has its own midi file.
Moreover, between chant books there are often subtle differences in ornamentation and harmonisation of the same chant.
These are the main reasons to provide for a midi file for each reference.
Please note that the midi files are provided solely as a tool to identify a particular chant or to compare chants. They are NOT intended to be reverse-engineered to obtain printed copy!! The purpose of the website is to be an index, for printed copy you should use the sources indicated with every chant book.
As of February 2019 the files are encoded to prevent reverse-engineering.
The midi files are created by entering the notes manually into Finale and saving the file as midi.
The Finale files are also exported as XML from which the fingerprint is obtained by a special program. The XML files are also used for further research.
The instrument used for the midi is a recorder (midi program 75) because the recorder ensemble sounds more or less like an organ with only a 4' stop.
This setup makes it easier to distinguish the separate voices, contrary to the midi-provided organ (midi program 20) which synthesizes multiple stops with many overtones.
In the case of an obligato organ part, the organ part is played on the midi church organ (program 20).
For questions about the midi files, please contact me at the address below.