- Extensions: au, snd
- Company: Sun
- MIME Types:
- snd, au: audio/basic, audio/x-basic, or audio/x-pn-au
AU, aka SND, is a simple PCM file format used widely on Sun systems. The format consists of a header followed by the raw sample data.
The format of the header is, with all numeric fields big endian:
magic 32 bits ".snd" data_start 32 absolute file offset of first sample data_size 32 size of sample data, 0 means unspecified sample_format 32 sample format code, see below sample_rate 32 sample rate in samples/second channels 32 number of channels
The header may be followed by a chunk of arbitrary data if the data_start field is greater than 24.
The sample format codes are:
0 unspecified 1 8-bit mu-law 2 8-bit signed linear 3 16-bit signed linear 4 24-bit signed linear 5 32-bit signed linear 6 floating-point 7 double precision float 8 fragmented sampled data 9 unknown 10 DSP program 11 8-bit fixed-point 12 16-bit fixed-point 13 24-bit fixed-point 14 32-bit fixed-point 15 unknown 16 non-audio data 17 mu-law squelch 18 16-bit linear with emphasis 19 16-bit linear with compression 20 16-bit linear with emphasis and compression 21 Music Kit DSP commands 22 Music Kit DSP samples 23 G.721 ADPCM 24 G.722 ADPCM 25 G.723 ADPCM 26 5-bit G.723 ADPCM 27 8-bit a-law