DSP Robotics Support

I'm working on a Sub-harmonizer that creates sound an octave lower than the input. It scans how th output changes and every time it goes from dropping to rising it switches the direction of how input transposes itself to output. The output would be off center so it is also constantly DC-blocked with simple highpass filter. After that you have a wave that looks like sum of 1/2 and 3/2 frequency sine waves of original sine wave. it is passed through wave-shaper so it becomes almost pure sinus.

This is just a core of the sub-harmonizer. in order to work for regular signal, the signal has to be pre-filtered to be almost pure sinewave (or similarly shaped wave). This filter is not included in this schematic - I'm still struggling with it. I was thinking maybe of pitch-tracking bandpass or lowpass.

Would not work something like this:

optional filter (lowpass, bandpass, whatever butterworth based, sharp slope) to get the band of interest -> pitch tracking --> pitch/frequency shifter --> mixer

?

I guess with such pitch tracking, filters could be applied too for selecting what part of harmonic content should be used for sub-adder (for example first few harmonics of vocal).

I had a version that used bandpass filters to split spectrum into semitones - so it was basically polyphonic. That was cool but also a CPU eater - 3 parallel code blocks (packed mono4) per octave. Had a really funny effect on the voice


http://www.mediafire.com/download/z2588kf8dc58fs0/octaver2.osm