Maybe you have a particular sound file(wave or mp3 files) that you wish to transfer into your 7650 or other mobile telephone through infrared, because the file size is too larger.
Now you can use WIDI to reduce the size of .wav .mp3 files before transferring! Just try it!
WIDI is designed to automate transcribing of music. That means that the task of retrieving music score from an audio record, which is usually accomplished by a hard work of a professional musicians,is about to be solvable by a computer. You can take you favorite audio record and convert it into notes.
WIDI allows both monophonic and polyphonic conversion. You can even record your own voice and then convert it into score! Then you can change it in any way, print, reassign instruments, cut off some notes, add new, etc. with your favorite MIDI Editor (such as CakeWalk).

Every musical note has pitch, which corresponds to the frequency of main tone. Modern musical scale has almost 100 pitches with frequencies from approximately 30 hertz to 4,5 kilohertz. Neighbor notes frequencies (C and C#, E and F) are always related as 2 in 1/12 power, so notes making an octave interval (=12 smallest called semitones) have frequencies rated as 1:2. There are other scales too, but they are rarely used. Every musical note has pitch, which corresponds to the frequency of main tone. Modern musical scale has almost 100 pitches with frequencies from approximately 30 hertz to 4,5 kilohertz. Neighbor notes frequencies (C and C#, E and F) are always related as 2 in 1/12 power, so notes making an octave interval (=12 smallest called semitones) have frequencies rated as 1:2. There are other scales too, but they are rarely used.

WIDI performs music recognition in several steps:

First it produces some kind of spectra-like data, this is called further the "WAVE->Pitch" conversion. Now there are two different algorithms implementing this step, each of them has its own advantages and disadvantages.
Then it multiplies that spectral data by coefficients of "Equalizer", making some pitches louder and some pitches more quiet (This is only for Widi for Windows version).
The third step is an actual retrieval of notes from the spectra, it is called "Pitch->MIDI" process and there are also two algorithms making that. The final step is producing the MIDI file structure, and you can choose some attributes of the output MIDI file. Nowadays investigations of more complex schemes are taking place, it seems that they will allow to differentiate musical instruments and make fewer errors.