NAME

       toast — GSM 06.10 lossy sound compression

SYNOPSIS

       toast [ -cdfpvhualsFC ] [ filename... ]

       untoast [ -cfpvhuaslF ] [ filename... ]

       tcat [ -vhuaslF ] [ filename... ]

DESCRIPTION

       Toast  compresses  the  sound files given on its command line.  Each file is replaced by a
       file with the extension .gsm .  If no files are specified, the compression is  applied  to
       the standard input, and its result is written to standard output.

       Toasted files can be restored to something not quite unlike their original form by running
       toast -d , or untoast , on the .gsm-files or standard input.

       The program tcat (the same as running untoast -c )  uncompresses  its  input  on  standard
       output, but leaves the compressed .gsm-files alone.

       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.

OPTIONS

       -c     (cat) Write to the standard output; no files are changed.

       -d     (decode) Decode, rather than encode, the files.

       -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.

       -p     (precious) Do not delete the source files.  Source files are implicitly left  alone
              whenever -c is specified or tcat is run.

       -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.
              The -C option applies only to the encoder and is silently ignored by the decoder.

       -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.
              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.
              The default is standard-conforming operation.

       -v     (version)  outputs the version of toast (or untoast or tcat) to stdout and exits.

       -h     (help)  prints a short overview of the options.

       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.
       The following formats are supported:

       -u     (μU-law) 8 kHz, 8 bit μU-law encoding (file suffix .u)

       -a     (A-law) 8 kHz, 8 bit A-law encoding (file suffix .A)

       -s     (Sun audio) 8 kHz, 8 bit μU-law encoding with audio header (file suffix .au)

       -l     (linear)  8  kHz,  16  bit  signed  linear  encoding  in  host  byte  order with 13
              significant bits (file suffix .l)

       In absence of options or suffixes to specify a format, μU-law encoding as forced by -u  is
       assumed.

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.

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.

BUGS

       Please direct bug reports to jutta@cs.tu-berlin.de.

SEE ALSO

       gsm(3)

                                              local                                      TOAST(1)