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/* -*- c-basic-offset: 4; indent-tabs-mode: nil -*- */
/* ====================================================================
* Copyright (c) 2006 Carnegie Mellon University. All rights
* reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* This work was supported in part by funding from the Defense Advanced
* Research Projects Agency and the National Science Foundation of the
* United States of America, and the CMU Sphinx Speech Consortium.
*
* THIS SOFTWARE IS PROVIDED BY CARNEGIE MELLON UNIVERSITY ``AS IS'' AND
* ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL CARNEGIE MELLON UNIVERSITY
* NOR ITS EMPLOYEES BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* ====================================================================
*
*/
/*********************************************************************
*
* File: fe_warp_affine.c
*
* Description:
* Warp the frequency axis according to an affine function, i.e.:
*
* w' = a * w + b
*
*********************************************************************/
/* static char rcsid[] = "@(#)$Id: fe_warp_affine.c,v 1.2 2006/02/17 00:31:34 egouvea Exp $"; */
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <string.h>
#ifdef _MSC_VER
#pragma warning (disable: 4996)
#endif
#include "sphinxbase/strfuncs.h"
#include "sphinxbase/err.h"
#include "fe_warp.h"
#include "fe_warp_affine.h"
#define N_PARAM 2
#define YES 1
#define NO 0
/*
* params[0] : a
* params[1] : b
*/
static float params[N_PARAM] = { 1.0f, 0.0f };
static int32 is_neutral = YES;
static char p_str[256] = "";
static float nyquist_frequency = 0.0f;
const char *
fe_warp_affine_doc()
{
return "affine :== < w' = a * x + b >";
}
uint32
fe_warp_affine_id()
{
return FE_WARP_ID_AFFINE;
}
uint32
fe_warp_affine_n_param()
{
return N_PARAM;
}
void
fe_warp_affine_set_parameters(char const *param_str, float sampling_rate)
{
char *tok;
char *seps = " \t";
char temp_param_str[256];
int param_index = 0;
nyquist_frequency = sampling_rate / 2;
if (param_str == NULL) {
is_neutral = YES;
return;
}
/* The new parameters are the same as the current ones, so do nothing. */
if (strcmp(param_str, p_str) == 0) {
return;
}
is_neutral = NO;
strcpy(temp_param_str, param_str);
memset(params, 0, N_PARAM * sizeof(float));
strcpy(p_str, param_str);
/* FIXME: strtok() is not re-entrant... */
tok = strtok(temp_param_str, seps);
while (tok != NULL) {
params[param_index++] = (float) atof_c(tok);
tok = strtok(NULL, seps);
if (param_index >= N_PARAM) {
break;
}
}
if (tok != NULL) {
E_INFO
("Affine warping takes up to two arguments, %s ignored.\n",
tok);
}
if (params[0] == 0) {
is_neutral = YES;
E_INFO
("Affine warping cannot have slope zero, warping not applied.\n");
}
}
float
fe_warp_affine_warped_to_unwarped(float nonlinear)
{
if (is_neutral) {
return nonlinear;
}
else {
/* linear = (nonlinear - b) / a */
float temp = nonlinear - params[1];
temp /= params[0];
if (temp > nyquist_frequency) {
E_WARN
("Warp factor %g results in frequency (%.1f) higher than Nyquist (%.1f)\n",
params[0], temp, nyquist_frequency);
}
return temp;
}
}
float
fe_warp_affine_unwarped_to_warped(float linear)
{
if (is_neutral) {
return linear;
}
else {
/* nonlinear = a * linear - b */
float temp = linear * params[0];
temp += params[1];
return temp;
}
}
void
fe_warp_affine_print(const char *label)
{
uint32 i;
for (i = 0; i < N_PARAM; i++) {
printf("%s[%04u]: %6.3f ", label, i, params[i]);
}
printf("\n");
}
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