refltofilt.3

来自「speech signal process tools」· 3 代码 · 共 78 行

.\" Copyright (c) 1986-1990 Entropic Speech, Inc.
.\" Copyright (c) 1991 Entropic Research Laboratory, Inc. All rights reserved.
.\" @(#)refltofilt.3	1.7 29 Jul 1991 ESI/ERL
.ds ]W (c) 1991 Entropic Research Laboratory, Inc.
.TH REFL_TO_FILTER 3\-ESPSsp 29 Jul 1991
.SH NAME

refl_to_filter \- Convert reflection coefficients to autoregressive filter coefficients.
.SH SYNOPSIS
.ft B
int
.br
refl_to_filter (refl_coeff, filter, size)
.br
float *refl_coeff, *filter;
.br
int size;
.SH DESCRIPTION
.PP
.I refl_to_filter
converts 
.I size \- 1
reflection coefficients,
.I refl_coeff,
(in positions 1 through
.I size \- 1
in the 
.I refl_coeff
array)
into the equivalent
.I size
autoregressive filter coefficients 
.I filter
(with the first coefficient being = \-1.0).
\fIrefl_to_filter\fR returns 1 on failure (one of the reflection coefficients
has magnitude > 1.0) and 0 on successful completion.
.PP
Note: this routine uses the sign convention for reflection coefficients
mentioned in FEA_ANA(5\-ESPS).
.SH EXAMPLE
.PP
.nf
/* We want to convert 3 reflection coefficients to
 * 4 autoregressive filter coefficients. Assume the
 * array \fIref_coeff\fP contains the reflection coefficients
 * starting from ref_coeff[0] to ref_coeff[2] and the
 * autoregressive filter coefficient array, \fIfilt_coeff\fP, has
 * enough memory to hold 4 coefficients.
 */

	int	size = 3;
	float	ref_coeff[3] = {	/* reflection coefficients */
		 \-0.248618, 0.81, 0.0
		};
	float	filt_coeff[4];	/* size + 1 array */

/* The following statement will convert the size ref_coeff
 * array to the proper size + 1 filt_coeff array.
 */

	refl_to_filter (ref_coeff \- 1, filt_coeff, 4);

/* Notice we are  sending (ref_coeff  \- 1)  pointer; it  is the one
 * before  ref_coeff[0].    Therefore,  in  refl_to_filt  routine,
 * refl_coeff[1]  will actually  be ref_coeff[0].
 */
.fi
.SH REFERENCES
[1] Programs for Digital Signal Processing, edited by the Digital Signal Processing
Committee, IEEE Acoustics, Speech, and Signal Processing Society, Chapter 4.3,
pp 4.3-1 to 4.3-7.
.SH "SEE ALSO"
.PP
rc_autopef(3\-ESPSsp)
.SH AUTHOR
Code by B. Fraenkel, manual page by D. Burton and A. Virdy.