Audio Speed/Pitch Changer
Speed up or slow down audio independently of pitch, or shift pitch independently of speed.
What is Speed & Pitch?
A time-stretch and pitch-shift tool for speeding up lectures, slowing down fast speech, transposing a track, or creating a deep-voice effect.
How it works
Tempo changes use ffmpeg's atempo filter, which time-stretches the audio while preserving pitch (chained for anything beyond 2× or below 0.5×). Pitch shifts resample the audio and then restore the original duration with a compensating atempo, so speed and pitch move independently.
- Load your file. Drag a file onto the drop zone or pick one from your device. It is read locally by the browser and never uploaded.
- Set the options. Adjust the handles, format, quality or threshold controls — the preview updates as you change them.
- Process and download. Run the tool, then download the result. Compare the reported before/after size for compressors and converters.
Examples
A 42 MB podcast episode → 9 MB MP3
Trim the intro, normalise to −16 LUFS, and export at 96 kbps mono — a typical interview lands around a fifth of the original size.
A phone video with the wrong orientation
Rotate 90° and the width/height swap in the output, so it plays upright in every player instead of relying on metadata flags.
Common mistakes
Expecting instant encoders
Video encoding runs in single-threaded WebAssembly, so a clip takes roughly its own length (or a little longer) to re-encode. Stream-copy operations are near-instant by comparison.
Re-encoding when a copy would do
Trimming, removing audio and joining same-codec clips can copy streams without re-encoding — pick the copy option when it is offered to avoid any quality loss.
Ignoring the first-load download
The media engine is about 31 MB and is fetched on first use, then cached. The first conversion on a connection is slower than every later one.
Frequently asked questions
What is the difference between speed and pitch?
Speed changes how long the clip takes; pitch changes the musical key. This tool changes each one without affecting the other.
How far can I push the speed?
0.25× to 4× is provided. Extreme values remain intelligible because the tempo filter preserves pitch, though 3× and above compress articulation noticeably.
Will it stay in sync with video?
Pitch shifting keeps the original duration by design, so the result still lines up with the video it came from. For video speed changes use the Video Speed Changer, which alters both together.