lsftopc.3

speech signal process tools

.\" Copyright (c) 1987-1990 Entropic Speech, Inc.
.\" Copyright (c) 1991-1997 Entropic Research Laboratory, Inc. All rights reserved.
.\" @(#)lsftopc.3	1.6 18 Apr 1997 ESI/ERL
.ds ]W (c) 1997 Entropic Research Laboratory, Inc.
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.TH LSF_TO_PC \3-ESPSsp 18 Apr 1997
.SH NAME

lsf_to_pc \- convert line spectral frequencies to linear prediction coefficients
.SH SYNOPSIS
.ft B
int lsf_to_pc(lsf, pc, order, bandwidth)
.br
float   pc[], lsf[], bandwidth;
.br
int     order;
.SH DESCRIPTION
This routine takes an input vector
.I lsf
of line spectral frequencies (see [1]) and computes the corresponding
linear prediction coefficients
.I pc,
also known as autoregressive filter coefficients
or prediction-error filter coefficients.
The convention adopted is that the first such coefficient is \-1,
and it does not appear in the output vector.
The argument
.I order
is the analysis filter order\*-i.e. the number of input
.I lsf
parameters and the number of output 
.I pc
coefficients\*-and
.I bandwidth
should equal one-half the sampling frequency of the original sampled data.
.SH ASSUMPTIONS
This routine assumes that 
.I order
is even.
.SH BUGS
None known.
.SH REFERENCES
[1] G. S. Kang and L. J. Fransen,
.I 
Low-Bit Rate Speech Encoders Based on Line-Spectrum Frequencies (LSFs),
NRL Report 8857, Naval Research Laboratory, Washington, D.C., January, 1985.
.SH AUTHOR
Manual page D. Burton, Code by D. Burton