Extract audio from video
In your browser, no upload
M4A
sound only · not re-encoded
Video
MP4 · MOV · M4V → M4ASpecification
7 rows| Item | Value | Notes |
|---|---|---|
| Input | MP4, MOV, M4V | Read from the file itself, not its name |
| Output | M4A | The sound track as it was stored, usually AAC |
| Length | Unchanged | Nothing is cut |
| Quality | Untouched | Nothing is decoded or encoded |
| Picture | Removed | Only the sound track goes into the new file |
| File size | No limit | Only the file’s index is read; the picture stays on disk |
| Processed in | This browser | Not sent to a server |
What happens
3What happens, and why
The sound of a video is a track of its own inside the file. Taking it out is writing a new file around that track alone: the compressed audio is copied across byte for byte, so what you get is the recording that was in the video, not a copy of a copy. Nothing is decoded and nothing is encoded, which is why the badge says the file was not re-encoded.
The result is an .m4a, which is an MP4 container holding sound only. It is what an iPhone, a camera and most screen recorders already store their audio as, so no conversion is needed to keep it: the file plays in Music, in QuickTime, on Android and in any browser. An MP3 would mean decoding this audio and encoding it again, and that is a second generation of loss for a file format that is not better.
A video with no sound track cannot give one, and the page says so rather than handing back an empty file.
FAQ
4Why .m4a and not .mp3
Because the sound in an MP4 or a MOV is almost always AAC, and an .m4a holds AAC as it is. Writing an MP3 would mean decoding the AAC and encoding it again — a lossy step on top of a lossy file, for no gain. This page copies instead, so the audio stays exactly what was recorded. When a device insists on MP3, the MP4 to MP3 page does that re-encode and says so.
Does it lose quality
No. The audio is not decoded at any point; the same compressed bytes are written into the new file. It is the recording itself, with a different container around it.
Can I get just part of the sound
Trim the video first on the trim page, then take the sound out of the trimmed file. Both steps copy, so the result is still the original recording.
Is the video uploaded
No. The browser reads the file from your disk and writes the new one on this page. There is no upload endpoint on this site, so there is nowhere for the file to go.