this is interesting. i never put a lot of thought into the "how", much more than this visual imagination of-- as a picture of a sound "wave", (e.g. Sound Forge, Digidesign, etc.,), and a sort of attempting to "match" them up-- as one would perhaps attempt to align /like/ layers of a multi-layer graphic using Pshop, or what not-- assuming those sections where matches are common, these have a higher percentage value in the Similarity rating mechanism.
however, this talk of DSP, and etc., it gets me to thinking of-- WOW-- it must be pretty involved-- more so than my imagining. for example, regarding DSP, FFT, etc., do you (soft dev'r) have also an extensive music theory knowledge? if so, or if not-- how do you feel that is involved in the perfection of such a machine (i.e. the software). For example, let's say we're using Antares auto-tune: now, one can fiddle about with that sort of thing-- but, to actually know what it means to produce a tone which is a perfect 5th above the original, or a "minor 3rd", so to speak-- such /skill/ is certainly advantageous to an engineer/ producer who might utilize such DSP equipment. so, i wonder-- how the notion comes into play here.
and i muse over this little bit of /trivia/ for you. i thought of my long-time friend, J.V., a senior software engineer w/ Sonic Foundry-turned-Sony-whatever-the-whatsis... pretty much runs the "Acid" project, development, and what not (indeed, i am "wow'd" by this myself, as i heard from a common friend-- not realizing he was that /into-it/-- that proficient-- that... how should i say... "/valuable/"?)... but he's just a dude, you know. played bass in this wild hardcore band in Morgantown, WV "Phat 'n Antsy"[1], along w/ other similarly gifted musicians, charismatic creators-- your basic bunch of genius kids pretending to be drug-addicts in a rock band-- you know. but-- i'm off the point-- point is-- i wonder if a guy like that being... ahem... bored, careerwise (so i hear)... might i should put the two of you in contact. i suppose i could begin by showing him the your web site, and "Similarity" itself. doh!
:-)
best regards. (something else from moi, coming soon-- having bump'd up to v. 1.10 from like version 0.02 or some ... hehe... stupid distractions, interruptions-- life-- when, the important stuff-- its the /music/, man! right? riiiggght! ;-)
[1]
Phat N Antsy: cid-f50063bb986b7eb4 . skydrive . live . com / browse . aspx / PNA