Convert AAC to Opus
We turn AAC into Opus right in your browser — the file never goes to a server.
What you will lose
Nothing important: the target format does everything the source does.
How they differ
| AAC | Opus | |
|---|---|---|
| Lossless | no | no |
| Lossy | yes | yes |
| Multichannel | yes | yes |
| Tags | yes | yes |
| Released | 1997 | 2012 |
| Author | MPEG | Xiph.Org, IETF |
AAC
Good at
- Noticeably better than MP3 at the same size
- The native format for Apple gear and most phones
- Handles multichannel audio and tags
Awkward about
- Older devices and car stereos may refuse it
- Lossy — the original cannot be recovered from it
- Encumbered by patents, unlike Opus
Use it when
- Listening on a phone without wasting quality
- A voice memo, or a track pulled out of a video
- You want a balance between size and sound
Opus
Good at
- The best quality at low bitrates — speech stays clear at 24 kbps
- The standard for voice: messengers, calls, streams
- Free, with no licensing fees
Awkward about
- Older devices and editors do not know it
- Car stereos and consumer players usually refuse it
- Lossy — not a master format
Use it when
- Voice: a podcast, an interview, a voice message
- You need the smallest size that still sounds clear
- The file is listened to in a browser or a messenger
Common questions
- Does the file get uploaded to a server?
- Yes, this pair needs the server: browsers cannot encode that format. The file and the result are deleted within a couple of hours and never shared.
- Will surround sound survive?
- Yes, Opus carries more than two channels — 5.1 stays 5.1.
- Can I get the original quality back afterwards?
- No. Opus is lossy, and the discarded detail cannot be recovered. Keep the original if you may still need it.
- How many files, and how large?
- Up to 10 files at a time, 200 MB each. No sign-up, no watermarks.