Video
Turn your MP4 files into AAC in seconds. Everything happens in your browser: nothing is uploaded to any server.
Drag your files here
Or paste them with Ctrl+V. They never leave your device.
At equal quality it takes slightly more space than a WebM with VP9. As AAC it sounds better than an MP3 of the same size.
MP4 is the most widespread video container; here it comes out with H.264 video and AAC audio, the most compatible combination.
Strengths: It plays on any phone, TV, browser or social network without installing anything.
Limits: At equal quality it takes slightly more space than a WebM with VP9.
AAC is the lossy audio codec that replaced MP3; this file is “raw” AAC, without a container (ADTS).
Strengths: At the same size it sounds better than an MP3 and almost every device understands it.
Limits: Without a container it holds no artwork or tags, and some programs prefer M4A.
No. The MP4 to AAC conversion runs entirely in your browser, with code downloaded from this site and executed on your device. You can check it in the Network tab of the developer tools or by going offline after the page loads.
Yes: in the options set the start and end time, for example from 1:30 to 2:45, and only that clip is extracted.
Up to 2 GB and 3 hours of video on desktop; on mobile, 500 MB and 30 minutes (AVI: 1 GB and 1 hour on desktop). If it is over, you are told before it starts and can trim it.
Yes. Drop as many MP4 files as you like: several are converted at the same time, depending on your processor cores, and when they finish you can download each AAC or all of them in a ZIP.