Audio format
The AAC format
AAC is a bare AAC audio stream without the M4A wrapper. AAC was standardised in 1997 as MP3’s successor; raw .aac files come from radio streams, recorders and TV captures.
When to use AAC
You rarely choose raw AAC; wrap it in M4A or convert to MP3 for normal use.
It is best for recordings captured from streams and broadcast, and it opens on most phones, browsers and players, though seeking and duration are often unreliable.
How to open it: VLC and most phones play .aac files.
| Full name | Advanced Audio Coding (raw stream) |
|---|---|
| Extensions | .aac, .adts |
| MIME type | audio/aac |
| Introduced | 1997 |
| Compression | Lossy |
| Typical quality | 96–256 kbps |
| Support | Opens almost everywhere |
| Typical size | About 1 MB a minute at 128 kbps |
Good at
- Better quality per megabyte than MP3
Not so good at
- No index, so players show the wrong length or can’t seek
- No cover art or proper tags
The common mistake
Raw AAC has no index, so players often show the wrong duration or can’t seek; saving it as M4A fixes both.
Questions
What is an AAC file?
AAC (Advanced Audio Coding (raw stream)) is a bare AAC audio stream without the M4A wrapper. AAC was standardised in 1997 as MP3’s successor; raw .aac files come from radio streams, recorders and TV captures.
How do I open an AAC file?
VLC and most phones play .aac files.
How do I convert AAC to another format?
Pick the target on this page, or open the Audio Converter, drop the AAC file and choose a format. It converts in your browser, so nothing is uploaded.