Video & audio · 2 min read ·
Extract MP3 from MP4 — right in your browser
Modern browsers can decode and encode media on their own. Here is how in-browser audio extraction works, without uploading the video.
A few years ago, pulling the soundtrack out of a video meant installing desktop software. Today, the browser's built-in media codecs and a small MP3 encoder can do it inside a tab.
The pipeline
The file is read from your disk into the page, the audio track is separated from the video (demuxed), decoded, re-encoded to MP3 and handed back to you as a download. The video itself never leaves your device.
On the desktop, the same job is a single ffmpeg command:
ffmpeg -i input.mp4 -vn -b:a 192k output.mp3Limits worth knowing
Because the work happens on your device, speed depends on your computer or phone, and very large files need enough memory. The 4Dev video converter accepts files up to 500 MB and also converts MOV, WebM and MKV, trims clips and outputs WAV, M4A, FLAC and OGG.