Pitch and duration are locked together when a file is simply played faster. Separating them means resampling one copy of the signal while the playhead keeps its original speed, then hiding the join.
Semitones and fine tune
Semitones moves the pitch in whole steps, up or down by 12. Fine tune adds up to 50 cents either way, which is half a semitone.
At exactly 0 semitones and 0 cents the wet path passes the input through unchanged, and the crossover happens over 20 ms so switching a shift in or out during playback does not step.
Common intervals: 12 is an octave, 7 a fifth, 5 a fourth, and 3 or 4 the minor and major third.
Grain
The shifted signal is read out of a delay line by a head that runs at the pitch ratio, wrapped around one grain. Two heads half a grain apart are crossfaded with matched windows that sum to exactly 1, so a steady tone comes through without a level ripple.
Grain sets how long that cycle is, from 20 to 120 ms. It is the trade every delay-based shifter makes: short grains repeat more often, long grains repeat a longer fragment.
Mix
Mix blends the shifted signal against the original. At 100% only the shifted version is heard.
Lower settings are where the interesting uses are. A 5 cent detune at 40% mix thickens a vocal without an audible pitch change, and a 12 semitone shift at 25% adds an octave under a bass line while the original note stays in front.
Where it struggles
Dense percussion smears, because a repeated grain lands in the middle of a transient. Solo instruments and voices survive better.
Shifts of more than about 5 semitones are audible as processing. If the goal is a clean transposition of a musical part, a smaller shift on a stem will always sound better than a large one on a finished mix.
Example: a backing vocal double
Semitones 0, fine tune 12 cents, grain 70 ms, mix 45%.
The take widens and sits behind the lead without landing on a different note.