isdisttd.3

speech signal process tools

.\" Copyright (c) 1987-1990 Entropic Speech, Inc.
.\" Copyright (c) 1997 Entropic Research Laboratory, Inc. All rights reserved.
.\" @(#)isdisttd.3	1.7 18 Apr 1997 ESI/ERL
.ds ]W (c) 1997 Entropic Research Laboratory, Inc.
.TH IS_DIST_TD 3\-ESPSsp 18 Apr 1997
.SH NAME
is_dist_td \- compute the Itakura-Saito distortion between two autoregressive power spectra given time domain information.
.SH SYNOPSIS
.ft B
double is_dist_td (autocorrn, autocorrn_err, codeword, codeword_err, size)
.br
double *autocorrn, autocorrn_err, *codeword, codeword_err;
.br
int     size;
.PP
.SH DESCRIPTION
.PP
.I is_dist_td
computes the
Itakura-Saito distortion  between two power spectra
that are defined by
.I autocorrn 
and 
.I codeword.
.I gnis_dist_td 
computes the distortion by using equation (7) in [1]
in which 
.I autocorrn 
corresponds to the first spectral argument and 
.I codeword 
corresponds to the second spectral argument.
.I autocorrn 
is a set of equally spaced, time-domain autocorrelations 
that start with the zero lag autocorrelation,
.I autocorrn_err
is the linear predictive analysis squared error that is associated with
the 
.I autocorrn
set of autocorrelations,
.I codeword
is 
the autocorrelation of autoregressive filter coefficients,
and
.I codeword_err
is the linear predictive analysis squared error term associated with
the 
.I codeword
set of filter coefficients.
.I size
is the number of 
.I autocorrn
and 
.I codeword
values, and
.I is_dist_td
returns the computed distortion value.
.SH WARNINGS
.PP
.I is_dist_td
ignores the first term (element 0) in the arrays,
.I autocorrn
and
.I codeword.
It assumes the arrays are defined from
.I autocorrn[1]
to
.I autocorrn[size]
and
.I codeword[1]
to
.I codeword[size].
.SH EXAMPLE
.PP
.nf
/* Assume the equally spaced, time-domain autocorrelation,
 * \fIauto_corr\fP,  is  defined  from  element 1  to element  6 and the
 * autocorrelation of the autoregressive filter coefficients,
 * \fIcdwd\fP, is defined from element 0 to element 5  (i.e. \fIsize\fP = 6).
 * Also assume that the linear predictive analysis squared error
 * terms \fIac_err\fP and \fIcdwd_err\fP have been computed. To compute
 * the Itakura-Saito distortion measure between the two power spectras,
 * we would have to call \fIis_dist_td\fP with the following arguments:
 */

    IS_distortion = is_dist_td(auto_corrn, ac_err, cdwd \- 1, cdwd_err, 6);
.fi
.SH REFERENCES
[1] J. E. Shore and D. K. Burton, Discrete Utterance Speech Recognition Without
Time Alignment," IEEE Transactions on Information Theory, Vol. IT-29, No. 4, July
1983, pp 473-491
.PP
[2] R. M. GRAY, A. Buzo, A. H. Gray, and Y. Matsuyama, "Distortion Measures for
Speech Processing," IEEE Transactions on Acoustics, Speech, and Signal Processing,
Vol. ASSP-28, No. 4, August 1980, pp 367-376
.SH "SEE ALSO"
.nf
\fIgnis_dist_td\fP(3\-ESPSsp), \fIgois_dist_td\fP(3\-ESPSsp)
.fi
.SH AUTHOR
Code by A. Virdy, manual page by D. Burton