Sample Rate Pitch Shift & Cents Calculator
Calculate musical pitch shift in semitones and cents, frequency ratio, playback speed change, and timeline drift caused by sample rate mismatches.
Sample Rates & Duration
Sample Rate Conversion, Pitch Shift and Varispeed
When digital audio recorded at one sample rate is played back at a different sample rate without sample rate conversion (resampling), both its pitch and playback speed change proportionally. This is identical to the mechanical "varispeed" effect on analog tape machines.
Acoustic Formulas
- Frequency Ratio:
Ratio R = Target Sample Rate / Source Sample Rate - Pitch Shift in Cents (1 Semitone = 100 Cents, 1 Octave = 1200 Cents):
ΔCents = 1200 × log₂(R) = 1200 × [ln(R) / ln(2)] - Pitch Shift in Semitones:
ΔSemitones = ΔCents / 100 = 12 × log₂(R) - Speed Change (%):
Speed Change (%) = (R - 1) × 100% - Timeline Drift per Hour:
Drift = 3600 × |1 - (1 / R)| seconds
44.1 kHz vs 48 kHz Mismatch
If a 44,100 Hz CD audio file is imported into a 48,000 Hz video project without resampling, it plays 8.84% faster and shifts up by +146.72 cents (almost one and a half semitones), drifting by over 5 minutes per hour!
Frequently Asked Questions
What is a cent in musical tuning?
A cent is a logarithmic unit of measure for musical intervals. In twelve-tone equal temperament, one octave is divided into 12 semitones of 100 cents each, totaling 1,200 cents per octave. Humans can typically detect pitch differences as small as 5 to 10 cents.
Why does film audio use 47,952 Hz (0.1% pull-down)?
When transferring 24 fps cinema film to 23.976 fps NTSC video, picture is slowed down by 0.1% (1000/1001). To maintain lip-sync without altering pitch via digital algorithms, audio sample rates are pulled down from 48,000 Hz to 47,952 Hz.
How do sound designers use sample rate pitch shifting for creature sounds?
Sound designers record animal vocalizations and mechanical impacts at high sample rates (96 kHz or 192 kHz) and play them back at 48 kHz or 44.1 kHz. This pitches the audio down by 1 to 2 full octaves while preserving ultrasonic high frequencies without aliasing artifacts.