| .\" |
| .\" Copyright 1992 by Jutta Degener and Carsten Bormann, Technische |
| .\" Universitaet Berlin. See the accompanying file "COPYRIGHT" for |
| .\" details. THERE IS ABSOLUTELY NO WARRANTY FOR THIS SOFTWARE. |
| .\" |
| .if n .ds mU u |
| .if t .ds mU \(*m |
| .\" |
| .TH TOAST 1 local |
| .SH NAME |
| toast \(em GSM\ 06.10 lossy sound compression |
| .SH SYNOPSIS |
| .ll +8 |
| .B toast |
| [ |
| .B \-cdfpvhualsFC |
| ] [ |
| .I "filename...\&" |
| ] |
| .LP |
| .B untoast |
| [ |
| .B \-cfpvhuaslF |
| ] [ |
| .I "filename...\&" |
| ] |
| .LP |
| .B tcat |
| [ |
| .B \-vhuaslF |
| ] [ |
| .I "filename...\&" |
| ] |
| .ll -8 |
| .SH DESCRIPTION |
| Toast compresses the sound files given on its command line. |
| Each file is replaced by a file with the extension |
| .I \&.gsm . |
| If no files are specified, the compression is applied to the |
| standard input, and its result is written to standard output. |
| .PP |
| Toasted files can be restored to something not quite unlike |
| their original form by running toast |
| .I "\-d" |
| , or |
| .I untoast |
| , on the \&.gsm-files or standard input. |
| .PP |
| The program |
| .I tcat |
| (the same as running |
| .I "untoast \-c" |
| ) uncompresses its input on standard output, |
| but leaves the compressed .gsm\-files alone. |
| .PP |
| When files are compressed or uncompressed into other files, |
| the ownership (if run by root), modes, accessed and modified times |
| are maintained between both versions. |
| .SH OPTIONS |
| .TP |
| .B \-c |
| (cat) |
| Write to the standard output; no files are changed. |
| .TP |
| .B \-d |
| (decode) |
| Decode, rather than encode, the files. |
| .TP |
| .B \-f |
| (force) |
| Force replacement of output files if they exist. |
| If \-f is omitted and toast (or untoast) is run interactively from |
| a terminal, the user is prompted as to whether the file should be replaced. |
| .TP |
| .B \-p |
| (precious) |
| Do not delete the source files. |
| Source files are implicitly left alone whenever \-c is |
| specified or tcat is run. |
| .TP |
| .B \-C |
| (LTP cut-off) |
| Ignore most sample values when calculating the GSM long-term |
| correlation lag during encoding. |
| (The multiplications that do this are a bottleneck |
| of the algorithm.) |
| The resulting encoding process will not produce |
| exactly the same results as GSM 06.10 would, |
| but remains close enough to be compatible. |
| .br |
| The |
| .B \-C |
| option applies only to the encoder and is silently |
| ignored by the decoder. |
| .TP |
| .B \-F |
| (fast) |
| On systems with a floating point processor, but without |
| a multiplication instruction, \-F sacrifices standard conformance to |
| performance and nearly doubles the speed of the algorithm. |
| .br |
| The resulting encoding and decoding process will not produce |
| exactly the same results as GSM 06.10 would, but remains close |
| enough to be compatible. |
| .br |
| The default is standard-conforming operation. |
| .TP |
| .B \-v |
| (version)\ |
| outputs the version of toast (or untoast or tcat) to stdout and exits. |
| .TP |
| .B \-h |
| (help)\ |
| prints a short overview of the options. |
| .PP |
| Toast, untoast and tcat try to guess the appropriate audio data |
| format from the file suffix. |
| Command line options can also specify a format to be used for |
| all files. |
| .br |
| The following formats are supported: |
| .TP |
| .B "\-u" |
| (\(*mU-law) |
| 8 kHz, 8 bit \(*mU-law encoding (file suffix .u) |
| .TP |
| .B "\-a" |
| (A-law) |
| 8 kHz, 8 bit A-law encoding (file suffix .A) |
| .TP |
| .B "\-s" |
| (Sun audio) |
| 8 kHz, 8 bit \(*mU-law encoding with audio header (file suffix .au) |
| .TP |
| .B "-l" |
| (linear) |
| 8 kHz, 16 bit signed linear encoding in host byte order |
| with 13 significant bits (file suffix .l) |
| .PP |
| In absence of options or suffixes to specify a format, |
| \(*mU-law encoding as forced by \-u is assumed. |
| .PP |
| .SH PECULIARITIES |
| A four bit magic number is prefixed to each 32 1/2-byte GSM frame, |
| mainly because 32 1/2-bytes are rather clumsy to handle. |
| .SH WARNING |
| The compression algorithm used is a lossy compression algorithm |
| devised especially for speech; on no account should it be used |
| for text, pictures or any other non-speech-data you consider |
| valuable. |
| .SH BUGS |
| Please direct bug reports to jutta@cs.tu-berlin.de. |
| .SH "SEE ALSO" |
| gsm(3) |
| .\" |
| .\" Toast is dedicated to Bill Sienkiewicz, author of "Stray Toasters". |