AU

Audio (AU) File Format files are a good example of a simple file type consisting of a header followed by data. There are actually two kinds of AU file. The suffix .au was originally introduced by Sun for headerless audio files containing ?-law compressed audio sampled at 8,000 samples per second. Subsequently, the the SND format was adopted on NeXT computers, and is the same as the AU format. AU files consists of a header with the following format followed by a single chunk of audio data. The numerical values in the header must be stored in big-endian format.

The following is the structure of an AU format file header:

Bytes	Offset	Content
4	0	Magic number: .snd
4	3	Offset of the sound data from the beginning of the file = 23 + N
4	7	Number of bytes of audio data
4	11	Sound format code
4	15	Sampling rate in samples per second
4	19	Number of channels
N	23	Optional text describing data
K	23+N	Audio data