What is the formula for pitch shifting?

The playback speed multiplier is 2 raised to the power of (semitones / 12). For example, shifting up 12 semitones (one octave) gives a multiplier of 2.0 — double speed. Shifting down 12 gives 0.5 — half speed.

What is the difference between the two FFmpeg commands?

The "Speed + Pitch" command changes both pitch and tempo together using the atempo filter — playback speed changes. The "Pitch Only" command uses the rubberband filter to shift pitch while keeping the original tempo (time-stretching). Rubberband must be compiled into your FFmpeg build.

Does rubberband need to be installed separately?

Yes. On Ubuntu/Debian run: sudo apt install librubberband-dev. On macOS with Homebrew: brew install rubberband. Then rebuild FFmpeg with --enable-librubberband, or install a pre-built FFmpeg that includes it (e.g. via Homebrew ffmpeg on macOS).

How many semitones are in an octave?

An octave spans exactly 12 semitones. Shifting by +12 semitones doubles the frequency; shifting by -12 halves it.

Can I shift by fractional semitones?

Yes. This tool accepts decimal values such as 0.5 (a quarter-tone) or -1.5. The 2^(n/12) formula works for any real number.

Audio Pitch Shifter

Name: Audio Pitch Shifter
Availability: InStock
Author: Nham Vu

Enter semitones to shift, get the speed multiplier and FFmpeg commands to pitch-shift audio files offline.

Pitch Shift Settings

Semitones to shift

Positive = pitch up, negative = pitch down. Decimals allowed (e.g. 0.5).

Input filename (for the FFmpeg command)

Quick pick (semitones)

Speed Multiplier

1.0000 × original speed

No pitch shift (0 semitones).

Frequency Ratio

1.0000 × original pitch (Hz)

Same value as speed multiplier — doubling frequency = one octave up.

FFmpeg — Speed + Pitch

Changes both pitch and tempo (shorter/longer playback).

FFmpeg — Pitch Only (rubberband)

Shifts pitch while keeping original tempo. Requires FFmpeg built with librubberband.

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Summary

Enter semitones to shift, get the speed multiplier and FFmpeg commands to pitch-shift audio files offline.

How it works

Enter the number of semitones to shift (positive = up, negative = down).
The speed multiplier is calculated instantly using the 2^(n/12) formula.
Choose whether to preserve the original tempo using the rubberband filter.
Copy the FFmpeg command and replace "input.mp3" with your actual filename.
Run the command in your terminal to produce the pitch-shifted audio file.

Use cases

Transpose a song to match a singers vocal range.
Create harmonies by copying an audio track and shifting it by thirds or fifths.
Slow down a track to half speed while keeping the same key.
Adjust the key of a backing track without re-recording.
Verify tuning: shift 12 semitones should sound exactly one octave up.
Prepare stems for remixes that need to be in a different key.

Frequently Asked Questions

Last updated: 2026-07-01 · Reviewed by Nham Vu