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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)