How to Extract Audio from a Video

In your browser

1. Open the Audio Converter. It takes MP4, MOV, WebM, MKV and other video formats.
2. Pick a quality. 192 kbps suits speech and most music; 320 kbps is the highest MP3 quality.
3. Drop in the video and download the MP3.

The conversion runs on your computer with FFmpeg, so the video is never uploaded. The first use downloads the converter, about 30 MB.

Choosing a format

• MP3 plays on everything.
• M4A (AAC) sounds better than MP3 at the same size and is what iPhones use.
• WAV or FLAC for editing, as they are lossless. They do not add quality the video did not have.

The Audio Converter saves to any of these.

With VLC

In VLC, choose Media → Convert / Save, add the video, click Convert / Save, pick the Audio - MP3 profile, choose where to save it, and click Start.

With FFmpeg

If you have FFmpeg installed, this saves the audio as a 192 kbps MP3:

ffmpeg -i video.mp4 -vn -c:a libmp3lame -b:a 192k audio.mp3

Most MP4 files already contain AAC audio, which can be copied out without re-encoding, instantly and with no quality loss:

ffmpeg -i video.mp4 -vn -c:a copy audio.m4a

How big the audio file will be

An MP3's size depends only on its bitrate and length, not on the video:

Size in MB = kbps × seconds ÷ 8000. A one-hour talk at 64 kbps mono is 28.8 MB and still clear for speech.

Common problems

• The MP3 is silent or the conversion fails. The video may have no audio track at all, which is common with screen recordings made without sound.
• The wrong language came out. Films and some recordings carry several audio tracks, and converters usually take the first. FFmpeg can pick another with -map 0:a:1 for the second track.
• 320 kbps sounds no better than the video. A higher bitrate cannot restore detail the video's own audio, often 128 kbps AAC, never had. It only makes the file bigger.
• Purchased or streamed videos will not open. Copy-protected files are encrypted and cannot be converted.