NAME

     pad  - pad (unpad) dead traces into USP  ensembles  (for  2D
     data); fix EOF short records

SYNOPSIS

     pad [ -Nntap ] [ -Ootap ] [ -ntrcntrc  ]  [  -nrecnrec  ]  [
     -Kkeywrd ] [ -R ] [ -P ] [ -rnum ] [ -use ] [ -tail ] [ -V ]
     [ -? ]

DESCRIPTION

     pad pads in dead traces into USP  ensembles  that  have  had
     them  stripped  out  (e.g.  DISCO  or  PROMAX USP conversion
     without putting in dead traces). This  is  also  useful  for
     storing  large  CDP  data sets on disk or tape since on some
     land data sets stripping out the dead traces can save up  to
     25%  on  storage. The program can be run in reverse to strip
     out dead traces.

     Also can be used to pad out a short record if  an  unantici-
     pated end of file (EOF) is encountered.

     It works by detecting when a key trace header word  changes.
     When it does it calls this an ensemble boundary and the pads
     the output record with an appropriate number of dead traces.
     In forward mode it reads input data until it hits the end of
     file. It will report the total number of live traces it read
     from  the  ensembles. In reverse mode it will read the input
     data, strip out the dead traces and write the live traces to
     the  output.  It  will  also report the total number of live
     traces it read from the input.  On  reverse  mode  the  line
     header  will  be  set  to  be  one record with the number of
     traces set equal to the  product  of  the  number  of  input
     traces  times  the number of records. This will be in excess
     of the actual number of live traces so the user should do an
     in-place utop to set the correct number of tracces.

     There is a 3D equivalent called pack3d which does esentially
     the  same operation. The 3D version however checks the min &
     max DI & LI entries in the line header in order to know  how
     to build its output records. The assumption then is that the
     data must be from one of the 3D sort programs.

     pad gets both its data and its parameters from command  line
     arguments.   These  arguments specify the input, output, the
     trace header word to  key  on,  optional  output  number  of
     traces/record  and  number of records, and verbose printout,
     if desired.

  Command line arguments
     -N ntap
          Enter the input data set name or file immediately after
          typing -N unless the input is from a pipe in which case
          the -N entry must be omitted.  This input  file  should
          include the complete path name if the file resides in a
          different directory.  Example -N/b/vsp/dummy tells  the
          program to look for file 'dummy' in directory '/b/vsp'.

     -O otap
          Enter the output data  set  name  or  file  immediately
          after typing -O.  This output file is not required when
          piping the output to another process.  The output  data
          set also requires the full path name (see above).

     -K keywrd
          Enter the trace header word  to  key  on  in  order  to
          detect ensemble boundaries. Default = RecNum

     -ntrc ntrc
          Enter  the  override   for   the   output   number   of
          traces/record. Default = input line header.

     -nrec nrec
          Enter the override for the output  number  of  records.
          Default = input line header.

     -R   Enter the command line argument '-R' to reverse the pad
          process,  i.e.  strip  out  dead  traces from the input
          data.

     -P   Enter the command line argument '-P' to keep one  trace
          in  a  completely  dead  record as a record placeholder
          upon the strip operation. This is then used to  rebuild
          the  dead  record  on the restore operation.  Note that
          sensible indexes will depend  on  whether  or  not  the
          first dead trace in a dead record has sensible indexes.

     -rnum
          Enter the command line argument '-rnum' to renumber the
          output traces, i.e. renumber RecNum and TrcNum.

     -use Enter the command line argument '-use' to use the  line
          header  number  of  records  to determine how many dead
          records to pad at the end when an unanticipated EOF  is
          encountered.  Otherwise  the  default is to pad out the
          last record of the input and stop.

     -tail
          Enter the command line argument '-tail' to pad a  short
          record at the end of a data set if an unanticipated EOF
          is encountered.  This  option  does  not  fill  in  any
          records up to that last record, i.e. does not do a for-
          ward pad operation. It's sole function is to take  care
          of truncated last records.

     -V   Enter the command line argument '-V' to get  additional
          printout.

     -?   Enter the command line  argument  '-?'  to  get  online
          help.   The program terminates after the help screen is
          printed.

EXAMPLES

     pad -Nindata -KDphInd -Ooutdata1

     end of forward pad, processed  7860 total live input traces

     The input data has  ensembles  with  a  variable  number  of
     traces  per  gather. Here the boundaries of the input ensem-
     bles were assumed to be marked by the depth index  (DphInd).
     The example above reported 7860 total live input traces pro-
     cessed.

     pad -Noutdata1 -KDphInd -Ooutdata2 -R

     end of reverse pad, processed  7860 total live input traces

     utop -Noutdata2 -Ooutdata2 -L7860

     Here the reverse operation has been run resulting in a  sin-
     gle  record of 7860 traces with all the dead traces stripped
     out. The final output line header has  been  fixed  properly
     with an in-place utop

BUGS

     unknown

SEE ALSO

     pack3d for 3D equivalent

AUTHOR

     Paul Gutowski

COPYRIGHT

     copyright 2001, Amoco Production Company
               All Rights Reserved
          an affiliate of BP America Inc.