fe_internal.h
/* -*- c-basic-offset: 4; indent-tabs-mode: nil -*- */
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* This work was supported in part by funding from the Defense Advanced
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* United States of America, and the CMU Sphinx Speech Consortium.
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#ifndef __FE_INTERNAL_H__
#define __FE_INTERNAL_H__
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#include "sphinxbase/fe.h"
#include "sphinxbase/fixpoint.h"
#ifdef __cplusplus
extern "C" {
#endif
#if 0
/* Fool Emacs. */
}
#endif
#ifdef FIXED16
/* Q15 format */
typedef int16 frame_t;
typedef int16 window_t;
typedef int32 powspec_t;
typedef struct { int16 r, i; } complex;
#elif defined(FIXED_POINT)
typedef fixed32 frame_t;
typedef int32 powspec_t;
typedef fixed32 window_t;
typedef struct { fixed32 r, i; } complex;
#else /* FIXED_POINT */
typedef float64 frame_t;
typedef float64 powspec_t;
typedef float64 window_t;
typedef struct { float64 r, i; } complex;
#endif /* FIXED_POINT */
/* Values for the 'logspec' field. */
enum {
RAW_LOG_SPEC = 1,
SMOOTH_LOG_SPEC = 2
};
/* Values for the 'transform' field. */
enum {
LEGACY_DCT = 0,
DCT_II = 1,
DCT_HTK = 2
};
typedef struct melfb_s melfb_t;
struct melfb_s {
float32 sampling_rate;
int32 num_cepstra;
int32 num_filters;
int32 fft_size;
float32 lower_filt_freq;
float32 upper_filt_freq;
/* DCT coefficients. */
mfcc_t **mel_cosine;
/* Filter coefficients. */
mfcc_t *filt_coeffs;
int16 *spec_start;
int16 *filt_start;
int16 *filt_width;
/* Luxury mobile home. */
int32 doublewide;
char const *warp_type;
char const *warp_params;
uint32 warp_id;
/* Precomputed normalization constants for unitary DCT-II/DCT-III */
mfcc_t sqrt_inv_n, sqrt_inv_2n;
/* Value and coefficients for HTK-style liftering */
int32 lifter_val;
mfcc_t *lifter;
/* Normalize filters to unit area */
int32 unit_area;
/* Round filter frequencies to DFT points (hurts accuracy, but is
useful for legacy purposes) */
int32 round_filters;
};
/* sqrt(1/2), also used for unitary DCT-II/DCT-III */
#define SQRT_HALF FLOAT2MFCC(0.707106781186548)
struct fe_s {
cmd_ln_t *config;
int refcount;
float32 sampling_rate;
int16 frame_rate;
int16 frame_shift;
float32 window_length;
int16 frame_size;
int16 fft_size;
uint8 fft_order;
uint8 feature_dimension;
uint8 num_cepstra;
uint8 remove_dc;
uint8 log_spec;
uint8 swap;
uint8 dither;
uint8 transform;
float32 pre_emphasis_alpha;
int32 seed;
int16 frame_counter;
uint8 start_flag;
uint8 reserved;
/* Twiddle factors for FFT. */
frame_t *ccc, *sss;
/* Mel filter parameters. */
melfb_t *mel_fb;
/* Half of a Hamming Window. */
window_t *hamming_window;
/* Temporary buffers for processing. */
/* FIXME: too many of these. */
int16 *spch;
frame_t *frame;
powspec_t *spec, *mfspec;
int16 *overflow_samps;
int16 num_overflow_samps;
int16 prior;
};
#define BB_SAMPLING_RATE 16000
#define DEFAULT_BB_FFT_SIZE 512
#define DEFAULT_BB_FRAME_SHIFT 160
#define DEFAULT_BB_NUM_FILTERS 40
#define DEFAULT_BB_LOWER_FILT_FREQ 133.33334
#define DEFAULT_BB_UPPER_FILT_FREQ 6855.4976
#define NB_SAMPLING_RATE 8000
#define DEFAULT_NB_FFT_SIZE 256
#define DEFAULT_NB_FRAME_SHIFT 80
#define DEFAULT_NB_NUM_FILTERS 31
#define DEFAULT_NB_LOWER_FILT_FREQ 200
#define DEFAULT_NB_UPPER_FILT_FREQ 3500
void fe_init_dither(int32 seed);
/* Apply 1/2 bit noise to a buffer of audio. */
int32 fe_dither(int16 *buffer, int32 nsamps);
/* Load a frame of data into the fe. */
int fe_read_frame(fe_t *fe, int16 const *in, int32 len);
/* Shift the input buffer back and read more data. */
int fe_shift_frame(fe_t *fe, int16 const *in, int32 len);
/* Process a frame of data into features. */
int32 fe_write_frame(fe_t *fe, mfcc_t *fea);
/* Initialization functions. */
int32 fe_build_melfilters(melfb_t *MEL_FB);
int32 fe_compute_melcosine(melfb_t *MEL_FB);
void fe_create_hamming(window_t *in, int32 in_len);
void fe_create_twiddle(fe_t *fe);
/* Miscellaneous processing functions. */
void fe_spec2cep(fe_t * fe, const powspec_t * mflogspec, mfcc_t * mfcep);
void fe_dct2(fe_t *fe, const powspec_t *mflogspec, mfcc_t *mfcep, int htk);
void fe_dct3(fe_t *fe, const mfcc_t *mfcep, powspec_t *mflogspec);
#ifdef __cplusplus
}
#endif
#endif /* __FE_INTERNAL_H__ */
melfb_s
Base Struct to hold all structure for MFCC computation.
Definition: fe_internal.h:89
cmd_ln_t
Opaque structure used to hold the results of command-line parsing.
fe_s
Structure for the front-end computation.
Definition: fe_internal.h:124
complex
Definition: f2c.h:16