SphinxBase  0.6
fe_internal.h
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37 
38 #ifndef __FE_INTERNAL_H__
39 #define __FE_INTERNAL_H__
40 
41 #ifdef HAVE_CONFIG_H
42 #include <config.h>
43 #endif
44 
45 #include "sphinxbase/fe.h"
46 #include "sphinxbase/fixpoint.h"
47 
48 #ifdef __cplusplus
49 extern "C" {
50 #endif
51 #if 0
52 /* Fool Emacs. */
53 }
54 #endif
55 
56 #ifdef FIXED16
57 /* Q15 format */
58 typedef int16 frame_t;
59 typedef int16 window_t;
60 typedef int32 powspec_t;
61 typedef struct { int16 r, i; } complex;
62 #elif defined(FIXED_POINT)
63 typedef fixed32 frame_t;
64 typedef int32 powspec_t;
65 typedef fixed32 window_t;
66 typedef struct { fixed32 r, i; } complex;
67 #else /* FIXED_POINT */
68 typedef float64 frame_t;
69 typedef float64 powspec_t;
70 typedef float64 window_t;
71 typedef struct { float64 r, i; } complex;
72 #endif /* FIXED_POINT */
73 
74 /* Values for the 'logspec' field. */
75 enum {
76  RAW_LOG_SPEC = 1,
77  SMOOTH_LOG_SPEC = 2
78 };
79 
80 /* Values for the 'transform' field. */
81 enum {
82  LEGACY_DCT = 0,
83  DCT_II = 1,
84  DCT_HTK = 2
85 };
86 
87 typedef struct melfb_s melfb_t;
89 struct melfb_s {
90  float32 sampling_rate;
91  int32 num_cepstra;
92  int32 num_filters;
93  int32 fft_size;
94  float32 lower_filt_freq;
95  float32 upper_filt_freq;
96  /* DCT coefficients. */
97  mfcc_t **mel_cosine;
98  /* Filter coefficients. */
99  mfcc_t *filt_coeffs;
100  int16 *spec_start;
101  int16 *filt_start;
102  int16 *filt_width;
103  /* Luxury mobile home. */
104  int32 doublewide;
105  char const *warp_type;
106  char const *warp_params;
107  uint32 warp_id;
108  /* Precomputed normalization constants for unitary DCT-II/DCT-III */
109  mfcc_t sqrt_inv_n, sqrt_inv_2n;
110  /* Value and coefficients for HTK-style liftering */
111  int32 lifter_val;
112  mfcc_t *lifter;
113  /* Normalize filters to unit area */
114  int32 unit_area;
115  /* Round filter frequencies to DFT points (hurts accuracy, but is
116  useful for legacy purposes) */
117  int32 round_filters;
118 };
119 
120 /* sqrt(1/2), also used for unitary DCT-II/DCT-III */
121 #define SQRT_HALF FLOAT2MFCC(0.707106781186548)
122 
124 struct fe_s {
125  cmd_ln_t *config;
126  int refcount;
127 
128  float32 sampling_rate;
129  int16 frame_rate;
130  int16 frame_shift;
131 
132  float32 window_length;
133  int16 frame_size;
134  int16 fft_size;
135 
136  uint8 fft_order;
137  uint8 feature_dimension;
138  uint8 num_cepstra;
139  uint8 remove_dc;
140  uint8 log_spec;
141  uint8 swap;
142  uint8 dither;
143  uint8 transform;
144 
145  float32 pre_emphasis_alpha;
146  int32 seed;
147 
148  int16 frame_counter;
149  uint8 start_flag;
150  uint8 reserved;
151 
152  /* Twiddle factors for FFT. */
153  frame_t *ccc, *sss;
154  /* Mel filter parameters. */
155  melfb_t *mel_fb;
156  /* Half of a Hamming Window. */
157  window_t *hamming_window;
158 
159  /* Temporary buffers for processing. */
160  /* FIXME: too many of these. */
161  int16 *spch;
162  frame_t *frame;
163  powspec_t *spec, *mfspec;
164  int16 *overflow_samps;
165  int16 num_overflow_samps;
166  int16 prior;
167 };
168 
169 #define BB_SAMPLING_RATE 16000
170 #define DEFAULT_BB_FFT_SIZE 512
171 #define DEFAULT_BB_FRAME_SHIFT 160
172 #define DEFAULT_BB_NUM_FILTERS 40
173 #define DEFAULT_BB_LOWER_FILT_FREQ 133.33334
174 #define DEFAULT_BB_UPPER_FILT_FREQ 6855.4976
175 
176 #define NB_SAMPLING_RATE 8000
177 #define DEFAULT_NB_FFT_SIZE 256
178 #define DEFAULT_NB_FRAME_SHIFT 80
179 #define DEFAULT_NB_NUM_FILTERS 31
180 #define DEFAULT_NB_LOWER_FILT_FREQ 200
181 #define DEFAULT_NB_UPPER_FILT_FREQ 3500
182 
183 void fe_init_dither(int32 seed);
184 
185 /* Apply 1/2 bit noise to a buffer of audio. */
186 int32 fe_dither(int16 *buffer, int32 nsamps);
187 
188 /* Load a frame of data into the fe. */
189 int fe_read_frame(fe_t *fe, int16 const *in, int32 len);
190 
191 /* Shift the input buffer back and read more data. */
192 int fe_shift_frame(fe_t *fe, int16 const *in, int32 len);
193 
194 /* Process a frame of data into features. */
195 int32 fe_write_frame(fe_t *fe, mfcc_t *fea);
196 
197 /* Initialization functions. */
198 int32 fe_build_melfilters(melfb_t *MEL_FB);
199 int32 fe_compute_melcosine(melfb_t *MEL_FB);
200 void fe_create_hamming(window_t *in, int32 in_len);
201 void fe_create_twiddle(fe_t *fe);
202 
203 /* Miscellaneous processing functions. */
204 void fe_spec2cep(fe_t * fe, const powspec_t * mflogspec, mfcc_t * mfcep);
205 void fe_dct2(fe_t *fe, const powspec_t *mflogspec, mfcc_t *mfcep, int htk);
206 void fe_dct3(fe_t *fe, const mfcc_t *mfcep, powspec_t *mflogspec);
207 
208 #ifdef __cplusplus
209 }
210 #endif
211 
212 #endif /* __FE_INTERNAL_H__ */
Base Struct to hold all structure for MFCC computation.
Definition: fe_internal.h:89
Opaque structure used to hold the results of command-line parsing.
Structure for the front-end computation.
Definition: fe_internal.h:124
Definition: f2c.h:16