diff options
Diffstat (limited to 'media/sphinxbase/src/libsphinxbase/fe/fe_warp_piecewise_linear.c')
| -rw-r--r-- | media/sphinxbase/src/libsphinxbase/fe/fe_warp_piecewise_linear.c | 223 |
1 files changed, 223 insertions, 0 deletions
diff --git a/media/sphinxbase/src/libsphinxbase/fe/fe_warp_piecewise_linear.c b/media/sphinxbase/src/libsphinxbase/fe/fe_warp_piecewise_linear.c new file mode 100644 index 000000000..34570120f --- /dev/null +++ b/media/sphinxbase/src/libsphinxbase/fe/fe_warp_piecewise_linear.c @@ -0,0 +1,223 @@ +/* -*- 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_piecewise_linear.c + * + * Description: + * + * Warp the frequency axis according to an piecewise linear + * function. The function is linear up to a frequency F, where + * the slope changes so that the Nyquist frequency in the warped + * axis maps to the Nyquist frequency in the unwarped. + * + * w' = a * w, w < F + * w' = a' * w + b, W > F + * w'(0) = 0 + * w'(F) = F + * w'(Nyq) = Nyq + * + *********************************************************************/ + +/* static char rcsid[] = "@(#)$Id: fe_warp_piecewise_linear.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_piecewise_linear.h" + +#define N_PARAM 2 +#define YES 1 +#define NO 0 + +/* + * params[0] : a + * params[1] : F (the non-differentiable point) + */ +static float params[N_PARAM] = { 1.0f, 6800.0f }; +static float final_piece[2]; +static int32 is_neutral = YES; +static char p_str[256] = ""; +static float nyquist_frequency = 0.0f; + + +const char * +fe_warp_piecewise_linear_doc() +{ + return "piecewise_linear :== < w' = a * w, w < F >"; +} + +uint32 +fe_warp_piecewise_linear_id() +{ + return FE_WARP_ID_PIECEWISE_LINEAR; +} + +uint32 +fe_warp_piecewise_linear_n_param() +{ + return N_PARAM; +} + +void +fe_warp_piecewise_linear_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)); + memset(final_piece, 0, 2 * 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 + ("Piecewise linear warping takes up to two arguments, %s ignored.\n", + tok); + } + if (params[1] < sampling_rate) { + /* Precompute these. These are the coefficients of a + * straight line that contains the points (F, aF) and (N, + * N), where a = params[0], F = params[1], N = Nyquist + * frequency. + */ + if (params[1] == 0) { + params[1] = sampling_rate * 0.85f; + } + final_piece[0] = + (nyquist_frequency - + params[0] * params[1]) / (nyquist_frequency - params[1]); + final_piece[1] = + nyquist_frequency * params[1] * (params[0] - + 1.0f) / (nyquist_frequency - + params[1]); + } + else { + memset(final_piece, 0, 2 * sizeof(float)); + } + if (params[0] == 0) { + is_neutral = YES; + E_INFO + ("Piecewise linear warping cannot have slope zero, warping not applied.\n"); + } +} + +float +fe_warp_piecewise_linear_warped_to_unwarped(float nonlinear) +{ + if (is_neutral) { + return nonlinear; + } + else { + /* linear = (nonlinear - b) / a */ + float temp; + if (nonlinear < params[0] * params[1]) { + temp = nonlinear / params[0]; + } + else { + temp = nonlinear - final_piece[1]; + temp /= final_piece[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_piecewise_linear_unwarped_to_warped(float linear) +{ + if (is_neutral) { + return linear; + } + else { + float temp; + /* nonlinear = a * linear - b */ + if (linear < params[1]) { + temp = linear * params[0]; + } + else { + temp = final_piece[0] * linear + final_piece[1]; + } + return temp; + } +} + +void +fe_warp_piecewise_linear_print(const char *label) +{ + uint32 i; + + for (i = 0; i < N_PARAM; i++) { + printf("%s[%04u]: %6.3f ", label, i, params[i]); + } + printf("\n"); +} |