MP4 to MP3
Pull the soundtrack out of an MP4 video and save it as MP3. Nothing is uploaded.
Drop MP4 files here
Converted on your device. Files are never uploaded.
Up to 20 files at a time.
Turning an MP4 into an MP3 keeps the sound of a lecture, concert clip or interview as an audio file you can play on any phone or in any music app. FormatJet extracts the audio in your browser and encodes the MP3 there as well, so the video never leaves your device.
About the formats
MP4MP4 video
MP4 is the most widely supported video format, used by phones, cameras and websites. It usually holds H.264 or HEVC video with AAC audio.
MP3MP3 audio
MP3 is the most widely supported audio format. Its lossy compression makes music about a tenth of the size of a CD, and every phone, car and player can play it.
Converted with Mediabunny, Browser audio decoder (WebCodecs), LAME MP3 encoder, Media engine (FFmpeg).
Questions
Can I paste a YouTube link here?
No. FormatJet converts MP4 files you already have on your device. It doesn’t take links and doesn’t download from YouTube or any other site.
What happens to the video picture?
It’s left out. Only the MP4’s sound goes into the MP3, and an MP4 that has no audio track is refused with a message explaining why.
Which bitrate should I pick for the MP3?
The Bitrate setting in Options starts at 192 kbps. Pick a higher choice for music you care about, which sounds better and makes a bigger file, or a lower one to keep a talk or podcast compact.
How is the MP3 made without uploading the video?
Your browser reads the MP4 with Mediabunny and decodes its audio with its own built-in decoder. LAME, the long-standing open-source MP3 encoder, then runs in the page as WebAssembly, so the counter stays at 0 bytes uploaded.
Will the MP3 line up with the video?
Yes. The MP3 has the same length and timing as the MP4, so you can match it back to the footage later.
MP4 to MP3 with the API
The conversion API opens later this year.
curl https://api.formatjet.com/v1/convert?to=mp3 \
-H "Authorization: Bearer fj_test_…" \
-F file=@input.mp4 -o output.mp3