[LAD] Audio2MIDI algorithms

It was a previous discussion "Musescore "music trainer"?", about polyphonic audio to MIDI recognition. I found a windows program that claim to archive good results : TallStick TS-AudioToMIDI On this webpage : http://tallstick.com/webhelp/algorithm.htm, they wrote some interesting claims : - "They (3 of the 4 algorithms) all are based on the set of oscillator circuits named sensors. Each sensor gets wave signal as input and produces some reply. Sensor's reply is a value proportional to the amplitude of component with frequency about equal to sensor's resonance one." This is what I call "filtre en peigne" in french. Comb filter. Each "teeth" of the comb will test for one frequency. - After sensor's output is multiplied on correspond Equalizer values, it arrives on Spectrum Window. All these methods analyze spectrum data at each instant of time from left to right (from low to high pitches). When spectral maximum is detected it assumed to be fundamental frequency of note. This assumption is tested by comparing spectra to Harmonic model setting. After this, if assumed note is greater than Threshold value then note accepts, otherwise rejects. If note is accepted, all it's spectral components are subtracted from corresponding components of whole spectra. This show that the whole algorithm is more complex than a simple recursive filtering. They take in account the spectra of the music. You can (and must) assign the instruments that play the music, before to made the conversion. Ciao, Dominique -- "We have the heroes we deserve."