Moin Robert & others, On 14.12.2010 06:15, robert bristow-johnson wrote: > this isn't a problem with piano, but what if the sample is of some acoustic > instrument with vibrato in the recording of a single note. then there isn't > an exact pitch for the whole sample of the note, because it varies in time.
Right, but if you consider 1/loop length the fundamental frequncy, vibrato becomes simple FM. This might sound stoopid, as we certainly perceive it our own time domain, but that does not mean we cannot take advantage of frequency domain processing. The problem here lies not so much in the frequency alignment itself but the pitch detection, which ideally finds a multiple of both the fundamental and the modulation frequency. In reality, if you choose your loop to be long enough, you can almost get away with any length, even if this is completely unrelated to the original pitch. Consider a 4 sec loop, all frequencies are multiples of 0.25 Hz. At 440 Hz, this difference is just 1 cent and hardly audible. Works for major as well as for minor chords, as for some 10CC not-in-love vocal cluster. > well, for sure you want the splice to be seamless for all harmonics, or > better yet "partials", of any appreciable magnitude. being that there are > non-harmonic partials in a lot of acoustic instruments, most certainly piano, > i know why you would want to adjust them a little so that phases of all > partials are aligned the jump in the loop is seamless. Yes, very seamless, I think this is what a loop should be. I cannot see how any frequency *not* being a multiple of the loop frequency could be represented in that loop. [...] > i suppose i could illustrate what i mean here with a bogus example, if i > haven't made it sufficiently clear. i just think that wavetable synthesis > has application that is broader than just playing single-cycle loops. To be honest I didn't quite get that. It could help if the unamed manufacturer could be named, I cannot yet see why it should remain anonymous. Regards, Stefan -- dupswapdrop -- the music-dsp mailing list and website: subscription info, FAQ, source code archive, list archive, book reviews, dsp links http://music.columbia.edu/cmc/music-dsp http://music.columbia.edu/mailman/listinfo/music-dsp
