Extract the audio from a video as MP3
The video to MP3 tool pulls the audio track out of an MP4, MOV, WebM, MKV, or AVI and saves it as an MP3. ffmpeg compiled to WebAssembly decodes the video's audio stream and the LAME encoder writes the MP3, all inside the browser tab, so the video is never uploaded.
Typical jobs: a recorded lecture or meeting to listen to on a walk, a voice memo that was saved as video, a song from a concert clip, or a podcast interview that was captured on camera.
The picture is discarded. Only the audio is decoded and re-encoded, which is far less work than re-encoding video, so even a long recording is a modest job.
Choosing a bitrate
The bitrate option has three settings: 128k, 192k, and 320k. It defaults to 192k.
128 kbps is fine for speech. Lectures, meetings, interviews, and voice notes lose nothing audible at this rate, and a one-hour recording comes to about 55 MB.
192 kbps is the default and suits most music and mixed content. Few listeners can tell it from the source on ordinary headphones, and an hour is about 85 MB.
320 kbps is the highest MP3 allows. Pick it for music you care about or for audio that will be edited again, since each further encode loses a little. An hour is about 140 MB.
The bitrate cannot add quality the source does not have. If the video's audio was recorded at 96 kbps, choosing 320k makes a bigger file with the same sound. When in doubt, 192k is the right answer.
What ends up in the file
The output keeps the base name and swaps the extension, so "interview.mp4" becomes "interview.mp3". The duration matches the video. If the video has no audio track, there is nothing to extract.
The MP3 size depends only on bitrate and duration, not on the video's resolution or file size. A 2 GB 4K recording and a 50 MB 480p recording of the same hour produce the same size MP3.
Why MP3
MP3 plays on everything made in the last twenty-five years: phones, car stereos, podcast apps, and every desktop player. Newer audio codecs are more efficient, but compatibility is the reason people ask for MP3, and that is what this tool produces. LAME, the encoder used here, is the same one that most desktop converters and ffmpeg builds rely on.
Related tools
If you want to keep the picture but make the file smaller, use compress video. If the file needs to play somewhere that rejects its current format, video to MP4 or video to WebM re-encode it with the audio intact. For a silent animated clip in an image format, video to GIF drops the audio and keeps the picture, the opposite of this tool.
Frequently asked questions
Which bitrate should I pick?
128k for speech, 192k for most music and mixed content, 320k for music you care about or audio that will be edited again. 192k is the default.
Will a higher bitrate improve the sound?
Only up to the quality of the source. If the video's audio was recorded at a low bitrate, 320k makes a bigger file with the same sound.
Which video formats are accepted?
MP4, MOV, WebM, MKV, and AVI. The tool takes video files only; it is not a general audio converter.
How big will the MP3 be?
About 55 MB per hour at 128k, 85 MB at 192k, and 140 MB at 320k, regardless of the video's size.
What if the video has no audio track?
Then there is nothing to extract and the job cannot produce a file.
What is the file called?
The same base name with an .mp3 extension, so 'interview.mp4' becomes 'interview.mp3'.