Moin Robert others, On 06.12.2010 19:49, robert bristow-johnson wrote: > > On Dec 6, 2010, at 1:23 PM, Stefan Stenzel wrote: > >> On 06.12.2010 08:59, robert bristow-johnson wrote: >>> >>> This is a continuation of the thread started by Element Green titled: >>> Algorithms for finding seamless loops in audio >> >> I suspect it works better to *construct* a seamless loop instead trying find >> one where there is none. > > i can't speak for Greenie or any others, but i myself would be very > interested in what you might have to say about constructing seamless loops. > regarding that, i would like to know the context (e.g. looping a non-realtime > sample editor for a sampling synth vs. a realtime pitch shifter) and the > kinds of signals (quasi-periodic vs. aperiodic vs. periodic but with detuned > higher harmonics). processing in frequency domain or time domain (or some in > both)?
I construct seemless loops in frequency domain in a non-realtime application, and I am quite happy with the results. If you ask for a recipe, this is what I am doing: - detect pitch of (whole) sample via AC (via FFT) - decide on block to be looped (behind attack segment, usually more than 1 s long) - detect frequency peaks in that block (frequency domain) - shift to integer fractions of loop length but preserve amplitude and initial phase - back to time domain - fade to loop in original sample (only played once as no fade is inside loop) > dunno if there is any PPG "secrets" or wisdom to confer, but i would like to > hear or read it. None of this in any PPG or Waldorf. Currently I use it for automatically looping huge piano sample sets, not for the memory but in order to fight noise. Tried it with other material like chords with surprisingly good results though. 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
