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audio - Inferno audio file format


Inferno audio files accepted by commands such as auplay(1) have a simple format. The file contains a header consisting of non-empty lines of text specifying the data format and characteristics, followed by an empty line, followed by the audio data in binary form. The data can be copied directly to a suitable audio device (see audio(3)) correctly configured, using read, write or stream (see sys-read(2)).

Each header line corresponds to a command that can be written to the control file audioctl of the audio(3) device. The first line of the header must be a rate command; other commands can appear in any order. The commands available are:

rate n
The data was recorded at n Hz, typically one of 44100, 22050, 11025 or 8000 but other values are legal.
chans n
There are n channels of audio data (eg, 1 for mono and 2 for stereo).
bits n
Each sample is n bits (typically 8 or 16).
enc e
The string e gives the recording format, and will usually be one of the following: ulaw, alaw, pcm or adpcm.

The audio data is stored with a sample from each channel in turn (`left' sample first if stereo, regardless of encoding or data size). Data encoded as pcm is little-endian, 2's complement if 16-bit, but unsigned if 8 bit. The adpcm encoding uses 4-bit samples (two mono samples or one stereo sample per byte, again little-endian).


auplay(1), audio(3)

AUDIO(6 ) Rev:  Thu Feb 15 14:43:48 GMT 2007