File extension AU is used for audio files in a format developed by Sub Microsystems. An AU sample file is provided. Free AU players and editors are listed.

File Extension: .AU

MIME Type: audio/basic

File Content: Audio data.

What is AU? AU is a file extension for audio files using an audio file format developed by Sun Microsystems.

Technical notes on AU file format:

• Originally, AU files only support a simple 8-bit u-law encoding at an 8000 Hz sample rate.
• Now, AU files support many audio encoding formats.

Here are the first 128 bytes of a sample AU file dumped in HEX values:

2e 73 6e 64 00 00 00 1c 00 01 6b f6 00 00 00 01 .snd......k.....
00 00 1f 40 00 00 00 01 00 00 00 00 7f 7f 7f 7f ................
7f 7f 7f 7f 7f 7f 7f 7f 7f 7f 7f 7f 7f 7f 7f 7f ................
7f 7f 7f 7f 7f 7f 7f 7f 7f 7f 7f 7f 7f 7f 7f 7f ................
7f 7f 7f 7f 7f 7f 7f 7f 7f 7f 7f 7f 7f 7f 7f 7f ................
7f 67 67 67 67 7f 67 7f 7f 67 ff 7f ff ff ff ff .gggg.g..g......
ff 7f 67 7f 7f ff ff ff 67 7f 7f 7f 67 67 67 7f ..g.....g...ggg.
67 7f 7f 67 67 7f 67 7f 7f 7f ff 7f ff 7f ff e7 g..gg.g.........

".snd" is the magic number of AU files.

AU sample file: Click sample.au to download.

Audio data stored in AU files can be retrieved and played by popular free software:

• Windows Media Player - Plays AU and other music files.
• MPlayer - Plays AU files and other audio files. An open source software.