# Convert MP4 to MP3

Turn any video into an MP3: MP4, MOV, MKV, WebM, or AVI.

## What's inside an MP4

Audo's MP4 to MP3 converter takes videos (MP4, MOV, MKV, WebM, AVI) up to 100 MB without an account and converts the first hour of each free, 10 times a day, with no sign-up. A 3-minute file is usually an MP3 in about 4 seconds.

An MP4 holds a picture track and a sound track, usually AAC, and sometimes subtitles. Converting keeps only the sound, as an MP3 that plays on phones, car stereos, podcast apps, and editors. If a video carries more than one sound track, you get the first.

The MP3 keeps about the same bitrate as the video's sound, from 64 to 320 kbps, and it's a small part of the video's size. Use it to listen to a talk or a lesson without watching it, or to send someone just the audio. To choose another format first, such as WAV or FLAC, use Extract audio from video.

Tool: Convert (`convert_audio`). The same tool's other pages: https://audo.ai/audio-converter.md, https://audo.ai/extract-audio-from-video.md, https://audo.ai/m4a-to-mp3.md, https://audo.ai/wav-to-mp3.md, https://audo.ai/mp3-to-wav.md, https://audo.ai/mov-to-mp3.md, https://audo.ai/ogg-to-mp3.md, https://audo.ai/flac-to-mp3.md, https://audo.ai/webm-to-mp3.md, https://audo.ai/aac-to-mp3.md, https://audo.ai/mp4-to-wav.md, https://audo.ai/m4a-to-wav.md, https://audo.ai/mp3-to-ogg.md, https://audo.ai/compress-audio.md, https://audo.ai/mkv-to-mp3.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=@video.mp4 -F format=mp3 https://audo.ai/api/try/convert -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#responses.

Free for the first hour of each file, 10 times a day per person, with no key or account. Uploads up to 100 MB, 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:

- `format`: The format to convert to: mp3, wav, m4a, flac, ogg, or opus. Default mp3.
- `bitrate_kbps`: The bitrate for mp3, m4a, ogg, or opus, in kbps (16 to 320), such as 128. Default: chosen for the format.
- `sample_rate`: The sample rate in Hz, such as 44100. Default: the input's.
- `channels`: mono or stereo. Default: the input's.

## 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 `convert_audio`:

> Converts a file to another audio format, or pulls the audio out of a video. Use it when the person needs MP3, WAV, M4A, FLAC, OGG, or Opus. Set free to true to do the first hour at no cost, up to 10 times a day; otherwise it costs 1 credit a minute. Returns job_id; then call get_job.

Example: "Use Audo to pull the audio out of launch-video.mp4 as an MP3."

## More

- Every tool: https://audo.ai/llms.txt
- OpenAPI: https://audo.ai/api/openapi.json
- This page for people: https://audo.ai/mp4-to-mp3