Return to Pitchshifter (thing)
How it worksA pitchshifting [algorithm] chops up a sound into [Granule|granules]. It then plays each granule back several times, not necessarily [integer], at a higher speed. This way, the [pitch] changes while the overall [duration] is maintained.
For example, let's [examine] a simple [sine wave] with a [frequency] of 440 [Hz]. The [period] of this wave is 1/440th of a second. In an ideal case we can get a granule that is exactly one period long, or any integer number of periods for that matter. Since this is as ideal as we're going to get, let's take any multiple of 1/440 seconds. Now, the pitchshifter takes grains of that length and plays each one back twice at double the speed. This results in a one [octave] pitchshift.
Unfortunately, pitchshifting like this is is only possible if you are doing sinewaves with equal periods. When pitchshifting a [complex] [waveform] (like a [guitar] part) it is [impossible] to choose a grain size of which the edges will [coincide] with the ends of all periods. In that case, pitchshifting will produce unwanted [artifact|artifacts] in the [frequency domain] that change the [timbre] of the sound.