Assignment 5, due Tuesday, May 24, is to extract the vocal part from this soundfile.

See the patches in this directory to find the tools you need to do it:

• 1.fiddle-and-table.pd: record a pitch track, measured using the fiddle~ object (the pitch tracker), and stored into an array for later use;
• 2.comb-filter.pd - how to make a comb filter using FFTs. The "comb" shape is really a pulse train, which has to be phase-locked to the FFTs. The 'time period' between pulses becomes the center frequency of the comb filter; the 'pulse width' becomes the bandwidth of each tooth of the comb.
• 3.sampler-window.pd - in case you find this useful: a way to freeze an FFT analysis on a particular grain of the incoming sound so you can tune things by ear. This patch also shows how to manage variable block sizes, which is useful for tuning your patch.

To do the homework:

• Download the soundfile and make a sample reader (tabplay~ will do fine).
• Make an FFT subwindow, in the mold of I03.resynthesis.pd.
• Use a pulse-width-modulation oscillator, like the one in 2.comb-filter.pd, to make a comb filter frequency response to multiply by the FFT analysis. You should make controls in the main window to control pitch (either in MIDI units or HZ.) and bandwidth (preferably in HZ., although I did it as a multiple of the fundamental analysis frequency SR/N).
• Make a pitch track of the soundfile. You'll have to edit this by hand to get even reasonable results. The pitches vary, roughly, between 60 and 70 in MIDI units.
• Make a sequencer that feeds the pitch track into the frequency input of the comb filter. The sequencer should start the soundfile playback automatically so that the two are in sync.
• Listening to the output, go back and tune the pitch track to agree as well as possible with the soundfile. There's no one best way to do this; careful listening and careful thought will help.