ref: 71292834bbafcf6bc409cfd7691f9e6650df025b
dir: /man/6/audio/
.TH AUDIO 6 .SH NAME audio \- Inferno audio file format .SH DESCRIPTION Inferno audio files accepted by commands such as .IR 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 .IR audio (3)) correctly configured, using .BR read , .B write or .B stream (see .IR sys-read (2)). .PP Each header line corresponds to a command that can be written to the control file .B audioctl of the .IR audio (3) device. The first line of the header must be a .BR rate command; other commands can appear in any order. The commands available are: .TP .BI rate " n" The data was recorded at .I n Hz, typically one of .BR 44100 , .BR 22050 , .BR 11025 or .BR 8000 but other values are legal. .TP .BI chans " n" There are .I n channels of audio data (eg, 1 for mono and 2 for stereo). .TP .BI bits " n" Each sample is .I n bits (typically 8 or 16). .TP .BI enc " e" .br The string .I e gives the recording format, and will usually be one of the following: .BR ulaw , .BR alaw , .BR pcm or .BR adpcm . .PP 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 .B pcm is little-endian, 2's complement if 16-bit, but unsigned if 8 bit. The .B adpcm encoding uses 4-bit samples (two mono samples or one stereo sample per byte, again little-endian). .SH SEE ALSO .IR auplay (1), .IR audio (3)