agc.c
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/*
* agc.c -- Various forms of automatic gain control (AGC)
*
* **********************************************
* CMU ARPA Speech Project
*
* Copyright (c) 1996 Carnegie Mellon University.
* ALL RIGHTS RESERVED.
* **********************************************
*
* HISTORY
* $Log$
* Revision 1.5 2005/06/21 19:25:41 arthchan2003
* 1, Fixed doxygen documentation. 2, Added $ keyword.
*
* Revision 1.3 2005/03/30 01:22:46 archan
* Fixed mistakes in last updates. Add
*
*
* 04-Nov-95 M K Ravishankar (rkm@cs.cmu.edu) at Carnegie Mellon University
* Created.
*/
#include <string.h>
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#include "sphinxbase/err.h"
#include "sphinxbase/ckd_alloc.h"
#include "sphinxbase/agc.h"
/* NOTE! These must match the enum in agc.h */
const char *agc_type_str[] = {
"none",
"max",
"emax",
"noise"
};
static const int n_agc_type_str = sizeof(agc_type_str)/sizeof(agc_type_str[0]);
agc_type_t
agc_type_from_str(const char *str)
{
int i;
for (i = 0; i < n_agc_type_str; ++i) {
if (0 == strcmp(str, agc_type_str[i]))
return (agc_type_t)i;
}
E_FATAL("Unknown AGC type '%s'\n", str);
return AGC_NONE;
}
agc_t *agc_init(void)
{
agc_t *agc;
agc = ckd_calloc(1, sizeof(*agc));
agc->noise_thresh = FLOAT2MFCC(2.0);
return agc;
}
void agc_free(agc_t *agc)
{
ckd_free(agc);
}
void
agc_max(agc_t *agc, mfcc_t **mfc, int32 n_frame)
{
int32 i;
if (n_frame <= 0)
return;
agc->obs_max = mfc[0][0];
for (i = 1; i < n_frame; i++) {
if (mfc[i][0] > agc->obs_max) {
agc->obs_max = mfc[i][0];
agc->obs_frame = 1;
}
}
E_INFO("AGCMax: obs=max= %.2f\n", agc->obs_max);
for (i = 0; i < n_frame; i++)
mfc[i][0] -= agc->obs_max;
}
void
agc_emax_set(agc_t *agc, float32 m)
{
agc->max = FLOAT2MFCC(m);
E_INFO("AGCEMax: max= %.2f\n", m);
}
float32
agc_emax_get(agc_t *agc)
{
return MFCC2FLOAT(agc->max);
}
void
agc_emax(agc_t *agc, mfcc_t **mfc, int32 n_frame)
{
int i;
if (n_frame <= 0)
return;
for (i = 0; i < n_frame; ++i) {
if (mfc[i][0] > agc->obs_max) {
agc->obs_max = mfc[i][0];
agc->obs_frame = 1;
}
mfc[i][0] -= agc->max;
}
}
/* Update estimated max for next utterance */
void
agc_emax_update(agc_t *agc)
{
if (agc->obs_frame) { /* Update only if some data observed */
agc->obs_max_sum += agc->obs_max;
agc->obs_utt++;
/* Re-estimate max over past history; decay the history */
agc->max = agc->obs_max_sum / agc->obs_utt;
if (agc->obs_utt == 8) {
agc->obs_max_sum /= 2;
agc->obs_utt = 4;
}
}
E_INFO("AGCEMax: obs= %.2f, new= %.2f\n", agc->obs_max, agc->max);
/* Reset the accumulators for the next utterance. */
agc->obs_frame = 0;
agc->obs_max = FLOAT2MFCC(-1000.0); /* Less than any real C0 value (hopefully!!) */
}
void
agc_noise(agc_t *agc,
mfcc_t **cep,
int32 nfr)
{
mfcc_t min_energy; /* Minimum log-energy */
mfcc_t noise_level; /* Average noise_level */
int32 i; /* frame index */
int32 noise_frames; /* Number of noise frames */
/* Determine minimum log-energy in utterance */
min_energy = cep[0][0];
for (i = 0; i < nfr; ++i) {
if (cep[i][0] < min_energy)
min_energy = cep[i][0];
}
/* Average all frames between min_energy and min_energy + agc->noise_thresh */
noise_frames = 0;
noise_level = 0;
min_energy += agc->noise_thresh;
for (i = 0; i < nfr; ++i) {
if (cep[i][0] < min_energy) {
noise_level += cep[i][0];
noise_frames++;
}
}
noise_level /= noise_frames;
E_INFO("AGC NOISE: max= %6.3f\n", MFCC2FLOAT(noise_level));
/* Subtract noise_level from all log_energy values */
for (i = 0; i < nfr; ++i)
cep[i][0] -= noise_level;
}
void
agc_set_threshold(agc_t *agc, float32 threshold)
{
agc->noise_thresh = FLOAT2MFCC(threshold);
}
float32
agc_get_threshold(agc_t *agc)
{
return FLOAT2MFCC(agc->noise_thresh);
}
agc_get_threshold
SPHINXBASE_EXPORT float32 agc_get_threshold(agc_t *agc)
Get the current AGC noise threshold.
Definition: agc.c:222
agc_noise
SPHINXBASE_EXPORT void agc_noise(agc_t *agc, mfcc_t **mfc, int32 n_frame)
Apply AGC using noise threshold to the given block of MFC vectors.
Definition: agc.c:180
agc_s::max
mfcc_t max
Estimated max for current utterance (for AGC_EMAX)
Definition: agc.h:114
agc_max
SPHINXBASE_EXPORT void agc_max(agc_t *agc, mfcc_t **mfc, int32 n_frame)
Apply AGC to the given mfc vectors (normalize all C0 mfc coefficients in the given input such that th...
Definition: agc.c:109
agc.h
routine that implements automatic gain control
ckd_calloc
#define ckd_calloc(n, sz)
Macros to simplify the use of above functions.
Definition: ckd_alloc.h:248
E_INFO
#define E_INFO
Print logging information to standard error stream.
Definition: err.h:147
ckd_alloc.h
Sphinx&#39;s memory allocation/deallocation routines.
agc_type_str
SPHINXBASE_EXPORT const char * agc_type_str[]
String representations of agc_type_t values.
Definition: agc.c:70
agc_s::obs_max
mfcc_t obs_max
Observed max in current utterance.
Definition: agc.h:115
agc_s::obs_frame
int32 obs_frame
Whether any data was observed after prev update.
Definition: agc.h:116
ckd_free
SPHINXBASE_EXPORT void ckd_free(void *ptr)
Test and free a 1-D array.
Definition: ckd_alloc.c:241
agc_init
SPHINXBASE_EXPORT agc_t * agc_init(void)
Initialize AGC structure with default values.
Definition: agc.c:91
agc_free
SPHINXBASE_EXPORT void agc_free(agc_t *agc)
Free AGC structure.
Definition: agc.c:100
agc_type_t
enum agc_type_e agc_type_t
Types of acoustic gain control to apply to the features.
agc_s::obs_utt
int32 obs_utt
Whether any utterances have been observed.
Definition: agc.h:117
agc_set_threshold
SPHINXBASE_EXPORT void agc_set_threshold(agc_t *agc, float32 threshold)
Set the current AGC noise threshold.
Definition: agc.c:216
agc_s::noise_thresh
mfcc_t noise_thresh
Noise threshold (for AGC_NOISE only)
Definition: agc.h:119
agc_emax_set
SPHINXBASE_EXPORT void agc_emax_set(agc_t *agc, float32 m)
Set the current AGC maximum estimate.
Definition: agc.c:129
err.h
Implementation of logging routines.
agc_s
Structure holding data for doing AGC.
Definition: agc.h:113
agc_emax_update
SPHINXBASE_EXPORT void agc_emax_update(agc_t *agc)
Update AGC parameters for next utterance.
Definition: agc.c:159
E_FATAL
#define E_FATAL
Exit with non-zero status after error message.
Definition: err.h:127
agc_emax
SPHINXBASE_EXPORT void agc_emax(agc_t *agc, mfcc_t **mfc, int32 n_frame)
Apply AGC to the given block of MFC vectors.
Definition: agc.c:142
agc_emax_get
SPHINXBASE_EXPORT float32 agc_emax_get(agc_t *agc)
Get the current AGC maximum estimate.
Definition: agc.c:136
agc_type_from_str
SPHINXBASE_EXPORT agc_type_t agc_type_from_str(const char *str)
Convert string representation (from command-line) to agc_type_t.
Definition: agc.c:79