LPsyn(1audio)

Routine
LPsyn [options] -p PFile -c LPFile AFileI [AFileO]

Purpose
LPC synthesis from a residual file

Description
This program does linear prediction synthesis given a file of residual samples and a file of linear prediction coefficients. The output is an audio file containing the reconstructed signal.

The steps involved in forming the linear prediction coefficients are as follows.
 1: Use the all-pole LPC filter to filter the residual signal
 2: Deemphasize the reconstructed signal

Options
Input file name: AFileI:
The environment variable AUDIOPATH specifies a list of directories to be searched for the input residual file.
Output file name: AFileO:
This name specifies the optional output file containing the reconstructed signal. Specifying "-" as the output file indicates that output is to be written to standard output.
-p PFile, --parameter_file=PFile
Parameter file.
-c LPFile, --lpc_file=LPFile
LPC predictor coefficient file.
-s, --statistics
Print frame-by-frame statistics.
-I INFO, --info=INFO
Audio file information string for the output file.
-h, --help
Print a list of options and exit.
-v, --version
Print the version number and exit.

The analysis parameters are read from the parameter file.
  preemphasis_factor = float  ! preemphasis factor (0 to 1, default 0)
  window_length = int         ! analysis window length
  window_offset = int         ! initial offset of the center of the analysis
                              ! window from the center of the frame (negative
                              ! values mean that the analysis window precedes
                              ! frame, default  0)
  window_type = char          ! window type (Hamming or rectangular, default
                              ! Hamming)
  frame_length = int          ! frame size
  LPC_number = int            ! number of LPC coefficients
  LPC_BW_expansion = float    ! bandwidth expansion factor (1 gives no
                              ! bandwidth expansion, default 1)

By default, the output file contains a standard audio file information string.
  Standard Audio File Information:
     date: 1994-01-25 19:19:39 UTC    date
     user: kabal@aldebaran            user
     program: LPsyn                   program name
     parameters: <parameters>         list of parameters
This information can be changed with the header information string which is specified as one of the command line options. Structured information records should adhere to the above format with a named field terminated by a colon, followed by numeric data or text. Comments can follow as unstructured information.
  Record delimiter: Newline character or the two character escape
      sequence "\" + "n".
  Line delimiter: Within records, lines are delimiteded by a carriage
      control character, the two character escape sequence "\" + "r",
      or the two character sequence "\" + newline.
If the information string starts with a record delimiter, the header information string is appended to the standard header information. If not, the user supplied header information string appears alone.

Environment variables
AUDIOPATH:
This environment variable specifies a list of directories to be searched when opening the input audio files. Directories in the list are separated by colons (semicolons for Windows).

Author / version
P. Kabal / v2r3b 2000-11-21 Copyright (C) 2000

See Also
LPanal, AFsp