Is there a way to loop a spectra properly in the SOS prototype?
I did a "perfect" loop on a wav file but when I convert it to spectra I can't
get close to the loop of the wav file; there is always a big gap in the loop.
I tried many analysis variant as well as many wav sources.
-- KarlMousseau - 10 Aug 2005
Record a wave file that goes through the loop three times. Do the spectral analysis of this file. Set the loop start and loop end to 1/3 and 2/3 to play the middle loop only. Alternatively, use the spectrum editor to delete the first and last loops, leaving the one in the middle.
-- CarlaScaletti - 10 Aug 2005
Now it loops properly, thanks! If I understand properly, the analysis process adds a "tail" to the actual sample?
Is it because of the "windowing" involved in the process?
-- KarlMousseau - 18 Aug 2005
Yes, in a way. The analysis takes a chunk of the sample, windows it, and then determines the amplitudes and the frequencies of the sine waves in that windowed chunk. The analysis then moves over in time a little and repeats this process (the chunks of samples actually overlap).
Before the beginning and after the ending of a sample, there is no signal defined; the analysis assumes that the signal is silent (which is the correct assumption for a one shot playback of the sample). However, for a loop, you don't want silence before and after the sample, you want a repetition of the sample, which is what the trick above does.
-- KurtHebel - 18 Aug 2005
Rather than trying to "loop" spectra, I find it easier to create a back & forth type
loop using a looped multisegment envelope. It doesn't require the kind of preparation
described here (set up your loop points & copy ...), but will only work well with spectra
that aren't objectionable when heard backwards. Most melodic instrument samples will work
well, spoken word might not ... depending on what you want.
-- RobRayle - 9 Feb 2006