SphinxBase  5prealpha
fe_warp_affine.c
1 /* -*- c-basic-offset: 4; indent-tabs-mode: nil -*- */
2 /* ====================================================================
3  * Copyright (c) 2006 Carnegie Mellon University. All rights
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18  * This work was supported in part by funding from the Defense Advanced
19  * Research Projects Agency and the National Science Foundation of the
20  * United States of America, and the CMU Sphinx Speech Consortium.
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22  * THIS SOFTWARE IS PROVIDED BY CARNEGIE MELLON UNIVERSITY ``AS IS'' AND
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37 /*********************************************************************
38  *
39  * File: fe_warp_affine.c
40  *
41  * Description:
42  * Warp the frequency axis according to an affine function, i.e.:
43  *
44  * w' = a * w + b
45  *
46  *********************************************************************/
47 
48 /* static char rcsid[] = "@(#)$Id: fe_warp_affine.c,v 1.2 2006/02/17 00:31:34 egouvea Exp $"; */
49 
50 #include <stdio.h>
51 #include <stdlib.h>
52 #include <math.h>
53 #include <string.h>
54 
55 #ifdef _MSC_VER
56 #pragma warning (disable: 4996)
57 #endif
58 
59 #include "sphinxbase/strfuncs.h"
60 #include "sphinxbase/err.h"
61 
62 #include "fe_warp.h"
63 #include "fe_warp_affine.h"
64 
65 #define N_PARAM 2
66 #define YES 1
67 #define NO 0
68 
69 /*
70  * params[0] : a
71  * params[1] : b
72  */
73 static float params[N_PARAM] = { 1.0f, 0.0f };
74 static int32 is_neutral = YES;
75 static char p_str[256] = "";
76 static float nyquist_frequency = 0.0f;
77 
78 
79 const char *
80 fe_warp_affine_doc()
81 {
82  return "affine :== < w' = a * x + b >";
83 }
84 
85 uint32
86 fe_warp_affine_id()
87 {
88  return FE_WARP_ID_AFFINE;
89 }
90 
91 uint32
92 fe_warp_affine_n_param()
93 {
94  return N_PARAM;
95 }
96 
97 void
98 fe_warp_affine_set_parameters(char const *param_str, float sampling_rate)
99 {
100  char *tok;
101  char *seps = " \t";
102  char temp_param_str[256];
103  int param_index = 0;
104 
105  nyquist_frequency = sampling_rate / 2;
106  if (param_str == NULL) {
107  is_neutral = YES;
108  return;
109  }
110  /* The new parameters are the same as the current ones, so do nothing. */
111  if (strcmp(param_str, p_str) == 0) {
112  return;
113  }
114  is_neutral = NO;
115  strcpy(temp_param_str, param_str);
116  memset(params, 0, N_PARAM * sizeof(float));
117  strcpy(p_str, param_str);
118  /* FIXME: strtok() is not re-entrant... */
119  tok = strtok(temp_param_str, seps);
120  while (tok != NULL) {
121  params[param_index++] = (float) atof_c(tok);
122  tok = strtok(NULL, seps);
123  if (param_index >= N_PARAM) {
124  break;
125  }
126  }
127  if (tok != NULL) {
128  E_INFO
129  ("Affine warping takes up to two arguments, %s ignored.\n",
130  tok);
131  }
132  if (params[0] == 0) {
133  is_neutral = YES;
134  E_INFO
135  ("Affine warping cannot have slope zero, warping not applied.\n");
136  }
137 }
138 
139 float
140 fe_warp_affine_warped_to_unwarped(float nonlinear)
141 {
142  if (is_neutral) {
143  return nonlinear;
144  }
145  else {
146  /* linear = (nonlinear - b) / a */
147  float temp = nonlinear - params[1];
148  temp /= params[0];
149  if (temp > nyquist_frequency) {
150  E_WARN
151  ("Warp factor %g results in frequency (%.1f) higher than Nyquist (%.1f)\n",
152  params[0], temp, nyquist_frequency);
153  }
154  return temp;
155  }
156 }
157 
158 float
159 fe_warp_affine_unwarped_to_warped(float linear)
160 {
161  if (is_neutral) {
162  return linear;
163  }
164  else {
165  /* nonlinear = a * linear - b */
166  float temp = linear * params[0];
167  temp += params[1];
168  return temp;
169  }
170 }
171 
172 void
173 fe_warp_affine_print(const char *label)
174 {
175  uint32 i;
176 
177  for (i = 0; i < N_PARAM; i++) {
178  printf("%s[%04u]: %6.3f ", label, i, params[i]);
179  }
180  printf("\n");
181 }
Miscellaneous useful string functions.
#define E_INFO(...)
Print logging information to standard error stream.
Definition: err.h:114
SPHINXBASE_EXPORT double atof_c(char const *str)
Locale independent version of atof().
Definition: strfuncs.c:55
Implementation of logging routines.
#define E_WARN(...)
Print warning message to error log.
Definition: err.h:109