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f6aec75 | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 | // C port of KeywordSpotter (see phoneme_engine/decoder.py for the
// reference semantics and design rationale).
#include "pww_decoder.h"
#include <string.h>
#include "model_int8.h"
#define NEG_INF (-1e30f)
// 200 ms/phone cap: looser caps let garbage alignments crawl across
// continuous background speech (see decoder.py)
#define MAX_FRAMES_PER_PHONE 10
// Confusable sets, mirroring decoder.py CONFUSABLE. Ids are 1-based
// (0 = CTC blank), matching PWW_PHONES order in model_int8.h:
// AA=1 AE=2 AH=3 AO=4 AW=5 AY=6 B=7 CH=8 D=9 DH=10 EH=11 ER=12 EY=13
// F=14 G=15 HH=16 IH=17 IY=18 JH=19 K=20 L=21 M=22 N=23 NG=24 OW=25
// OY=26 P=27 R=28 S=29 SH=30 T=31 TH=32 UH=33 UW=34 V=35 W=36 Y=37
// Z=38 ZH=39
static int confusable(uint8_t id, uint8_t out[PWW_DEC_MAX_ALLOWED]) {
switch (id) {
case 3: out[0] = 3; out[1] = 17; out[2] = 12; return 3; // AH
case 17: out[0] = 17; out[1] = 3; return 2; // IH
case 12: out[0] = 12; out[1] = 3; return 2; // ER
case 4: out[0] = 4; out[1] = 1; return 2; // AO
case 2: out[0] = 2; out[1] = 1; return 2; // AE
case 33: out[0] = 33; out[1] = 34; return 2; // UH
case 20: out[0] = 20; out[1] = 15; return 2; // K
case 15: out[0] = 15; out[1] = 20; return 2; // G
case 31: out[0] = 31; out[1] = 9; return 2; // T
case 9: out[0] = 9; out[1] = 31; return 2; // D
default: out[0] = id; return 1;
}
}
int pww_spotter_init(pww_spotter_t *sp, const uint8_t *phone_ids,
int n_phones, float threshold) {
if (n_phones < 2 || n_phones > PWW_DEC_MAX_PHONES) return -1;
memset(sp, 0, sizeof(*sp));
sp->n_phones = n_phones;
sp->threshold = threshold;
sp->strong_margin = 1.5f;
sp->strong_ratio = 0.5f;
sp->refractory = 50;
int n = 0;
// leading blank
sp->labels[n] = 0;
sp->preds[n][0] = 0; sp->preds[n][1] = -1;
sp->entry[n] = 1;
n++;
for (int i = 0; i < n_phones; i++) {
uint8_t pid = phone_ids[i];
int a = n;
if (i == 0) {
sp->labels[n] = pid;
sp->preds[n][0] = 0; sp->preds[n][1] = -1;
sp->entry[n] = 1;
n++;
} else {
sp->labels[n] = pid;
sp->preds[n][0] = (int8_t)(a - 1);
// skip the blank between different phones
sp->preds[n][1] = (sp->labels[a - 2] != pid)
? (int8_t)(a - 2) : -1;
sp->entry[n] = 0;
n++;
}
sp->labels[n] = pid; // B state, only from A
sp->preds[n][0] = (int8_t)a; sp->preds[n][1] = -1;
sp->entry[n] = 0;
n++;
sp->labels[n] = 0; // blank after phone
sp->preds[n][0] = (int8_t)(a + 1); sp->preds[n][1] = -1;
sp->entry[n] = 0;
n++;
}
sp->n_states = n;
for (int s = 0; s < n; s++)
sp->n_allowed[s] = (sp->labels[s] == 0)
? (sp->allowed[s][0] = 0, 1)
: (uint8_t)confusable(sp->labels[s], sp->allowed[s]);
sp->min_dur = 3 * n_phones;
sp->max_dur = MAX_FRAMES_PER_PHONE * n_phones;
pww_spotter_reset(sp);
return 0;
}
void pww_spotter_reset(pww_spotter_t *sp) {
for (int s = 0; s < sp->n_states; s++) {
sp->rel[s] = NEG_INF;
sp->start[s] = 0;
sp->pframes[s] = 0;
sp->strong[s] = 0;
}
sp->cooldown = 0;
sp->t = 0;
sp->best_seen = NEG_INF;
}
int pww_spotter_step(pww_spotter_t *sp, const float *logits,
float *score_out, int *dur_out) {
float filler = logits[0];
for (int c = 1; c < PWW_NUM_CLASSES; c++)
if (logits[c] > filler) filler = logits[c];
float rel[PWW_DEC_MAX_STATES];
int32_t start[PWW_DEC_MAX_STATES], pf[PWW_DEC_MAX_STATES],
strong[PWW_DEC_MAX_STATES];
for (int s = 0; s < sp->n_states; s++) {
float best = sp->rel[s];
int32_t b_start = sp->start[s], b_pf = sp->pframes[s],
b_sf = sp->strong[s];
for (int q = 0; q < 2; q++) {
int8_t p = sp->preds[s][q];
if (p >= 0 && sp->rel[p] > best) {
best = sp->rel[p];
b_start = sp->start[p];
b_pf = sp->pframes[p];
b_sf = sp->strong[p];
}
}
if (sp->entry[s] && 0.0f >= best) {
best = 0.0f; b_start = sp->t; b_pf = 0; b_sf = 0;
}
float emit = logits[sp->allowed[s][0]];
for (int a = 1; a < sp->n_allowed[s]; a++) {
float v = logits[sp->allowed[s][a]];
if (v > emit) emit = v;
}
int is_phone = sp->labels[s] != 0;
rel[s] = best + emit - filler;
start[s] = b_start;
pf[s] = b_pf + (is_phone ? 1 : 0);
strong[s] = b_sf +
((is_phone && emit >= filler - sp->strong_margin) ? 1 : 0);
}
memcpy(sp->rel, rel, sizeof(float) * sp->n_states);
memcpy(sp->start, start, sizeof(int32_t) * sp->n_states);
memcpy(sp->pframes, pf, sizeof(int32_t) * sp->n_states);
memcpy(sp->strong, strong, sizeof(int32_t) * sp->n_states);
sp->t++;
float norm_best = NEG_INF;
int norm_dur = 0, have = 0;
for (int f = 0; f < 2; f++) {
int s = sp->n_states - 1 - f;
int32_t dur = sp->t - sp->start[s];
int32_t p = sp->pframes[s];
if (dur < sp->min_dur || dur > sp->max_dur) continue;
if (p < 2 * sp->n_phones) continue;
if ((float)sp->strong[s] < sp->strong_ratio * (float)p) continue;
float norm = sp->rel[s] / (float)p;
if (!have || norm > norm_best) {
norm_best = norm; norm_dur = (int)dur; have = 1;
}
}
if (have && norm_best > sp->best_seen) sp->best_seen = norm_best;
if (sp->cooldown > 0) { sp->cooldown--; return 0; }
if (have && norm_best > sp->threshold) {
sp->cooldown = sp->refractory;
for (int s = 0; s < sp->n_states; s++) sp->rel[s] = NEG_INF;
*score_out = norm_best;
*dur_out = norm_dur;
return 1;
}
return 0;
}
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