Hi again, Just to briefly explain these two nice techniques as a couple of you have asked about them. They are both based on the same math, a kind of modified fast fourier transform which enables the software to stretch or shrink time without affecting pitch or sound timbre (the characteristic that enables us to recognize an instrument). Note tuning, only applicable to samples of monophonic instruments: the software has a freq detector that will find the nearest note to what is being played. It will find a starting time, end time and deviation for that. Then it will apply this FFT to generate a sample equal in duration but in tune. This is done by stretching or shrinking as appropriate first (this does not change pitch), then re-sampling to length which changes the pitch as required. Quantizer: only used for samples of percussion AFAIK, but should be applicable to other instruments with high attack like bass and others: first step is for the software to identify the location of the notes (that's the equivalent for MIDI events but this time in audio), by using a kind of peak detector this time instead of the freq detector for the other technique. Second step is to identify where the notes should exactly be time-wise. For this, it's neccessary that the software knows about the timing of the song / sample! (basically BPM and desired quantize resolution). Knowing this, it's pretty straightforward to "shrink and stretch" before and after the note so it falls exactly on time. These two give best results when the notes are not too off. This is due to this special FFT not being a perfect method to extract exactly everything that's there, especially high frequencies. Different implementations of these use different algorithms, all are based on a FFT, but some use different techniques to mask certain side effects that appear on the modified sample. Some implementations are very impressive I have to say, and they can stretch or shrink to say two times or half with brilliant results. All pretty impressive technology which has been around for a while now.. Cheers, Alex _________________________________________________________________ Hor?scopo, tarot, numerolog?a... Escucha lo que te dicen los astros. http://astrocentro.msn.es/
