# Speed up or slow down audio and video

Make audio or video faster or slower, keeping its pitch or not.

## How it works

1. Add an audio file or a video.
2. Pick a speed, such as 1.25× to speed up audio or 0.75× to slow down audio.
3. Press Change speed, listen, and download the new version.

## Speed, pitch, and tempo

Audo's audio speed changer speeds up and slows down audio (WAV, MP3, M4A, AAC, FLAC, OGG, Opus, WebM, AIFF) and video (MP4, MOV, MKV, WebM, AVI) up to 10 GB without an account, and the first 10 minutes of each file is free, 10 times a day, with no sign-up. It goes from 0.25× to 4×, in any step between, with the pitch kept or moving with the speed.

Played faster, a record sounds higher as well as quicker, because its waves arrive more often. Keeping the pitch pulls the two apart: the sound is stretched or squeezed in time while every note stays where it was. That's what speech, practice, and listening need. Letting the pitch follow is the sound of slowed and sped-up edits.

Tempo is counted in beats per minute, and it changes exactly with speed: a 100 BPM song at 1.2× plays at 120 BPM. To slow down audio for transcribing or learning, small steps such as 0.9× keep it natural. For a DJ edit, match one track's tempo to another's, then check that their keys mix with Key and BPM.

Tool: Change speed & pitch (`change_speed_pitch`). The same tool's other pages: https://audo.ai/change-pitch.md. Price: 1 credit a minute — $0.01/min ($0.60/hr), with no subscription — of input for whole files, charged only when a job succeeds.

## Free API

```bash
curl -F file=@lecture.mp3 -F speed=1.5 https://audo.ai/api/try/speed-pitch -D response.headers -o response.body
```

Read response.headers and response.body before naming media. Handle 202, 200 JSON and errors with the complete response client at https://audo.ai/docs/api?utm_source=markdown&utm_medium=agent#responses.

Free for the first 10 minutes of each file, 10 times a day per person, with no key or account. Uploads up to 10 GB, 2 at once from one address. The response is the result itself; a job that runs longer than about 30 seconds returns 202 with a link to check on it. With an API key (`-H "Authorization: Bearer $AUDO_API_KEY"`), omitting free runs the whole file with credits if the balance covers it, otherwise the free portion if quota remains. Set free=true to prohibit spending; for paid whole files use free=false with an approved positive max_credits. A free result cut short comes with finishUrl (and the Audo-Finish-Url header when the response is the file itself): give it to the person, who pays there (from $5, no sign-up), and the whole file runs; keep checking the status link, whose finishedBy names the whole-file job and its own status link. Details: https://audo.ai/docs/api.md

## Options

Form fields with the same names as the MCP tool's inputs:

- `speed`: How fast it plays: 1 is unchanged, 1.25 is 25% faster (shorter), 0.8 is 20% slower. 0.25 to 4. Default 1.
- `pitch_semitones`: How far to move the pitch, in semitones: 2 is up a whole step, -1 down a half step, 12 up an octave. -12 to 12, to 0.01. Default 0.
- `keep_pitch`: true changes the speed without changing the pitch. false changes both together, like a record played faster or slower (nightcore, slowed). pitch_semitones moves it further. Default true.
- `output_format`: The result's format: same (as the input; a video stays a video), wav, mp3, m4a, or flac. Default same.

## Languages

Any language: it works on the sound, not the words.

## From an assistant (MCP)

Add https://audo.ai/mcp and sign in (setup for each assistant: https://audo.ai/setup.md). The tool is `change_speed_pitch`:

> Changes how fast a recording plays, its pitch, or both: speed from 0.25x to 4x, and pitch up or down by up to 12 semitones. Speed keeps the pitch unless keep_pitch is false, which changes both together like a record (slowed or nightcore). Works on video: the picture follows the new speed. Use find_key_bpm first to reach a target tempo or key. It costs 1 credit a minute of input, charged only if the job succeeds. Returns the result with download links, or job_id for get_job if it takes longer.

Example: "Use Audo to speed up lecture.mp3 to 1.5x, keeping the pitch."

## Questions

**Is it free?** Yes. Audo is free for the first 10 minutes of each file, 10 times a day, with no sign-up. Whole files are $0.01 a minute ($0.60 an hour), with no subscription — see pricing.

**Will it sound like chipmunks when I speed it up?** Not with Keep the pitch on, as it is to begin with: voices and instruments stay at their own pitch, only faster or slower. Turn it off and the pitch moves with the speed, like a record played at the wrong speed.

**How do I make a slowed or nightcore version?** Turn Keep the pitch off. Around 0.8× gives the deep, dreamy sound of slowed edits, and around 1.25× the bright, high sound of nightcore. With the pitch free to move, 1.25× raises it by almost 4 semitones and 0.8× lowers it by as much.

**How do I change a song's BPM?** As a BPM changer, divide the tempo you want by the song's: from 120 to 126 BPM is 1.05×. Key and BPM finds the song's tempo for free, and its Change tempo button brings the file here, showing the new BPM as you pick.

**Can I speed up a lecture or a podcast?** Yes. At 1.5× a 60-minute lecture lasts 40 minutes, and 1.25× is easy to follow for most voices. To also cut the long pauses, use Remove silence.

**Does it work on video?** Yes. The picture speeds up or slows down with the sound, so they stay in sync, and you get a video back. For the sound on its own, pick MP3 or WAV under Save as in More options.

**How slow or fast can it go?** From a quarter of the speed (0.25×) to four times as fast (4×). For learning a fast solo or a lyric by ear, 0.5× to 0.75× with the pitch kept is the easiest to follow.

## More

- Every tool: https://audo.ai/llms.txt
- OpenAPI: https://audo.ai/api/openapi.json
- This page for people: https://audo.ai/change-speed?utm_source=markdown&utm_medium=agent