Video conversion
Convert MP4 to AAC
Updated Jul 2026
MP4 is a video file, and AAC is an audio-only format used by Apple devices and most streaming apps. To convert MP4 to AAC, pull the audio track out of the video and save it on its own. Doing this on your own computer means the video, whatever it shows, never has to leave your machine.
- Extension
- .mp4
- Type
- Video
- Typically
- The universal video format
- Compression
- Lossy
- Extension
- .aac
- Type
- Audio
- Typically
- Apple / streaming audio
- Compression
- Lossy
Convert MP4 to AAC on your own computer. Nothing uploads.
How to convert MP4 to AAC
- Open Morphjet and drag in the MP4 file, or a whole folder of them, that you want the audio from.
- Choose AAC as the output format.
- Convert. Morphjet writes the audio file next to your original, and nothing is uploaded anywhere.
MP4 vs AAC: what actually changes
| MP4 | AAC | |
|---|---|---|
| Contains video | Yes | No, audio only |
| File size | Large, the video track dominates the size | Much smaller, since it's just the sound |
| Quality | Depends on the source, but usually lossy | Very good at normal settings, with a small loss from lossy compression |
| Compatibility | Plays in nearly any video app or browser | Native on Apple devices and most streaming and podcast apps |
| Typical use | Watching or editing video | Listening, on a phone, in a car, or in a music library |
When to convert, and when not to
Convert MP4 to AAC when you only need the sound, like pulling the narration out of a screen recording, turning a talk or lecture video into something you can listen to on a commute, or getting a song out of a music video without keeping the picture around.
Keep the MP4 if you still need the video itself, since converting to AAC throws the picture away for good.
Why not just use an online converter?
The audio inside an MP4 can carry someone's voice, a private conversation, or a recording you'd rather not hand to a stranger's server. An online converter has to receive the whole video file before it can pull out the sound. Converting on your own computer skips that step entirely, so the file stays where it started.
Questions
Does converting MP4 to AAC lose quality?
There's usually a small, one-time loss, since AAC is a lossy format. At normal settings it's hard to notice by ear, but if the video's audio was already compressed, you won't get back quality that wasn't there to begin with.
What happens to the video when I convert to AAC?
It's dropped. AAC only holds audio, so converting MP4 to AAC gives you the sound track as its own file and leaves the picture behind. Keep the original MP4 if you might want the video later.
Is AAC the same as MP3?
No, they're different audio formats, though both are lossy and widely supported. AAC is the format Apple devices default to, and it generally sounds better than MP3 at the same file size.
Can I convert MP4 to AAC without uploading the video?
Yes. Morphjet does the conversion on your own computer, so the video never has to travel over the internet. It works the same with your wifi off.
Will the AAC file keep any metadata from the MP4?
Basic details like title or track info can carry over if the MP4 had them, but MP4 metadata is often about the video itself, so there isn't always much audio-relevant metadata to keep.
Morphjet converts MP4, AAC, and 1,800+ other formats, all on your machine. Launching this July.