Sun AU Audio (.AU)
AU is an audio file format introduced by Sun Microsystems and commonly associated with Unix and NeXT systems. It supports various encodings including uncompressed PCM, mu-law, and A-law compression, with a simple header structure. AU was one of the earliest audio formats supported on the web and remains used in Unix-based audio programming.
Advantages of Sun AU Audio
What the AU format does well, and why you might choose it.
- Simple, well-documented format with a minimal header
- Native support in Unix, Solaris, and Java audio APIs
- Supports multiple encoding types including mu-law for telephony
Limitations of Sun AU Audio
What the AUformat doesn't do well, and when to choose another format.
- Largely obsolete for general-purpose audio use
- Limited metadata support and no modern compression options
- Poor support in consumer audio software and devices
What AU files are used for
- Unix and Solaris system audio and sound effects
- Java application audio playback (javax.sound)
- Legacy telephony and voice processing systems
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Frequently asked questions about AU
What is a .AU file?
AU is an audio file format introduced by Sun Microsystems and commonly associated with Unix and NeXT systems. It supports various encodings including uncompressed PCM, mu-law, and A-law compression, with a simple header structure. AU was one of the earliest audio formats supported on the web and remains used in Unix-based audio programming.
What is the MIME type of AU?
The official MIME type for AU files is audio/basic. This is the value web servers and applications use to identify the format when transferring files.
What category does AU belong to?
AU is a Audio Converter format. Files in this category share common conversion paths and use cases.
How do I open a .AU file?
AU files are typically opened by software that natively supports the Sun AU Audioformat. If you don't have a compatible application, the most reliable approach is to convert the file to a more universal format using the converters listed above. Most Sun AU Audio files convert to widely-supported alternatives in seconds.
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