Choice criteria could be summarised as below:
| CRITERION | AUDIO | MIDI |
| Space requirement and treatment duration | high | low |
| Complete data | very good | average |
| Precise data | average | very good |
| Noise and interference tolerance | low | high |
| Coding treatment functions | quite difficult | quite easy |
| Could be applied to everykind of instrument | yes | no |
| Allow system to be adapted to the source instrument | yes | no |
| Could be applied to polyphonic music | with difficulty | yes |
A choice is difficult because of the complementarity of both data types. Moreover, the Score Following system described in document "Background - Existing Systems" gives two kinds of Score Followers: one with Audio Input, the other with MIDI input.
We can't make a choice without knowing which kind of music will be played. If we have for example a Chopin's piece, i.e. a polyphonic piano piece, we will obviously choose MIDI as input, whereas if we have a study for flute, i.e. a simple monophonic piece, audio will be more efficient.
Another (and the last) choice criterion will be the time we will have to realise the system. Since input data type does not affect other functions too much, we will focus on only one type, as the first realisation step, and then consider the second input type as a program extention.
MIDI data allow to test the system without having to store a big amount of data. Moreover, we can easily produce a MIDI-score and a test MIDI-performance with artificial errors, which is more difficult with audio.
Our first goal will be to use MIDI data as input for the system. Detection algorithms will be implemented and tested first with a MIDI input, and only then extended to audio.