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Before I give some more detailed tips, I will generally describe how this all works.
If you want to pitch up a sound, you can achive this by playing the sound faster
and thus compressing the wave (on the time axis). Unfortunately this makes the
sound shorter as well. To compensate this, SoundFX will repeat small chunks of
sound to stretch the sample. While doing this SoundFX has to take care that those
chunks fit relative seamingless together to avoid crackles. The winsize parameter
determines how far SFX searches maximaly for a good transition. The size depends
on the material to pitch-. I recomend smaller values (30-50 ms) for percussive
samples (this avoids that attacks are repeated audible) and longer values (100-200
ms) for synth/pad/string sounds (to avoid loops).
If the modulator is a sine wave and
a small pitchfactor is used (+/- 10 ct), you'll get a vibrato effect.
If you'd like to manipulate synthetic waveforms that have a constant period you
should enter the period in Winsize. This'll produce clean pitchshifts.
Factors shouldn't exceed 4.0 with sampled sounds as such high factors result in
bad pitchshifts (this is due to the way the pitchshifter works). Synthetic waveforms
can be pitchshifted however the far you like.
If the result contains crackles try to slightly change the window-size and/or raise
the smooth value.
If you want to make a sample longer/shorter without changing the pitch, do it in
the following way : You want to make a sample twice as long
- use Resample with factor 2.0
- adjust Samplingrate (use the old value)
- and start PitchShift with a factor of 2.0
Now the sample has the same pitch as before, but is twice long as before.
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