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Diffstat (limited to 'media/pocketsphinx/src/ngram_search.c')
| -rw-r--r-- | media/pocketsphinx/src/ngram_search.c | 1409 |
1 files changed, 0 insertions, 1409 deletions
diff --git a/media/pocketsphinx/src/ngram_search.c b/media/pocketsphinx/src/ngram_search.c deleted file mode 100644 index 47e488c3af..0000000000 --- a/media/pocketsphinx/src/ngram_search.c +++ /dev/null @@ -1,1409 +0,0 @@ -/* -*- c-basic-offset: 4; indent-tabs-mode: nil -*- */ -/* ==================================================================== - * Copyright (c) 2008 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 ngram_search.c N-Gram based multi-pass search ("FBS") - */ - -/* System headers. */ -#include <string.h> -#include <assert.h> - -/* SphinxBase headers. */ -#include <sphinxbase/ckd_alloc.h> -#include <sphinxbase/listelem_alloc.h> -#include <sphinxbase/err.h> - -/* Local headers. */ -#include "pocketsphinx_internal.h" -#include "ps_lattice_internal.h" -#include "ngram_search.h" -#include "ngram_search_fwdtree.h" -#include "ngram_search_fwdflat.h" - -static int ngram_search_start(ps_search_t *search); -static int ngram_search_step(ps_search_t *search, int frame_idx); -static int ngram_search_finish(ps_search_t *search); -static int ngram_search_reinit(ps_search_t *search, dict_t *dict, dict2pid_t *d2p); -static char const *ngram_search_hyp(ps_search_t *search, int32 *out_score, int32 *out_is_final); -static int32 ngram_search_prob(ps_search_t *search); -static ps_seg_t *ngram_search_seg_iter(ps_search_t *search, int32 *out_score); - -static ps_searchfuncs_t ngram_funcs = { - /* name: */ "ngram", - /* start: */ ngram_search_start, - /* step: */ ngram_search_step, - /* finish: */ ngram_search_finish, - /* reinit: */ ngram_search_reinit, - /* free: */ ngram_search_free, - /* lattice: */ ngram_search_lattice, - /* hyp: */ ngram_search_hyp, - /* prob: */ ngram_search_prob, - /* seg_iter: */ ngram_search_seg_iter, -}; - -static ngram_model_t *default_lm; - -static void -ngram_search_update_widmap(ngram_search_t *ngs) -{ - char const **words; - int32 i, n_words; - - /* It's okay to include fillers since they won't be in the LM */ - n_words = ps_search_n_words(ngs); - words = (char const**)ckd_calloc(n_words, sizeof(*words)); - /* This will include alternates, again, that's okay since they aren't in the LM */ - for (i = 0; i < n_words; ++i) - words[i] = dict_wordstr(ps_search_dict(ngs), i); - ngram_model_set_map_words(ngs->lmset, words, n_words); - ckd_free(words); -} - -static void -ngram_search_calc_beams(ngram_search_t *ngs) -{ - cmd_ln_t *config; - acmod_t *acmod; - - config = ps_search_config(ngs); - acmod = ps_search_acmod(ngs); - - /* Log beam widths. */ - ngs->beam = logmath_log(acmod->lmath, cmd_ln_float64_r(config, "-beam"))>>SENSCR_SHIFT; - ngs->wbeam = logmath_log(acmod->lmath, cmd_ln_float64_r(config, "-wbeam"))>>SENSCR_SHIFT; - ngs->pbeam = logmath_log(acmod->lmath, cmd_ln_float64_r(config, "-pbeam"))>>SENSCR_SHIFT; - ngs->lpbeam = logmath_log(acmod->lmath, cmd_ln_float64_r(config, "-lpbeam"))>>SENSCR_SHIFT; - ngs->lponlybeam = logmath_log(acmod->lmath, cmd_ln_float64_r(config, "-lponlybeam"))>>SENSCR_SHIFT; - ngs->fwdflatbeam = logmath_log(acmod->lmath, cmd_ln_float64_r(config, "-fwdflatbeam"))>>SENSCR_SHIFT; - ngs->fwdflatwbeam = logmath_log(acmod->lmath, cmd_ln_float64_r(config, "-fwdflatwbeam"))>>SENSCR_SHIFT; - - /* Absolute pruning parameters. */ - ngs->maxwpf = cmd_ln_int32_r(config, "-maxwpf"); - ngs->maxhmmpf = cmd_ln_int32_r(config, "-maxhmmpf"); - - /* Various penalties which may or may not be useful. */ - ngs->wip = logmath_log(acmod->lmath, cmd_ln_float32_r(config, "-wip")) >>SENSCR_SHIFT; - ngs->nwpen = logmath_log(acmod->lmath, cmd_ln_float32_r(config, "-nwpen")) >>SENSCR_SHIFT; - ngs->pip = logmath_log(acmod->lmath, cmd_ln_float32_r(config, "-pip")) >>SENSCR_SHIFT; - ngs->silpen = ngs->pip - + (logmath_log(acmod->lmath, cmd_ln_float32_r(config, "-silprob"))>>SENSCR_SHIFT); - ngs->fillpen = ngs->pip - + (logmath_log(acmod->lmath, cmd_ln_float32_r(config, "-fillprob"))>>SENSCR_SHIFT); - - /* Language weight ratios for fwdflat and bestpath search. */ - ngs->fwdflat_fwdtree_lw_ratio = - cmd_ln_float32_r(config, "-fwdflatlw") - / cmd_ln_float32_r(config, "-lw"); - ngs->bestpath_fwdtree_lw_ratio = - cmd_ln_float32_r(config, "-bestpathlw") - / cmd_ln_float32_r(config, "-lw"); - - /* Acoustic score scale for posterior probabilities. */ - ngs->ascale = 1.0 / cmd_ln_float32_r(config, "-ascale"); -} - -ps_search_t * -ngram_search_init(ngram_model_t *lm, - cmd_ln_t *config, - acmod_t *acmod, - dict_t *dict, - dict2pid_t *d2p) -{ - ngram_search_t *ngs; - static char *lmname = "default"; - - /* Make the acmod's feature buffer growable if we are doing two-pass - * search. */ - acmod_set_grow(acmod, cmd_ln_boolean_r(config, "-fwdflat") && - cmd_ln_boolean_r(config, "-fwdtree")); - - ngs = ckd_calloc(1, sizeof(*ngs)); - ps_search_init(&ngs->base, &ngram_funcs, config, acmod, dict, d2p); - ngs->hmmctx = hmm_context_init(bin_mdef_n_emit_state(acmod->mdef), - acmod->tmat->tp, NULL, acmod->mdef->sseq); - if (ngs->hmmctx == NULL) { - ps_search_free(ps_search_base(ngs)); - return NULL; - } - ngs->chan_alloc = listelem_alloc_init(sizeof(chan_t)); - ngs->root_chan_alloc = listelem_alloc_init(sizeof(root_chan_t)); - ngs->latnode_alloc = listelem_alloc_init(sizeof(ps_latnode_t)); - - /* Calculate various beam widths and such. */ - ngram_search_calc_beams(ngs); - - /* Allocate a billion different tables for stuff. */ - ngs->word_chan = ckd_calloc(dict_size(dict), - sizeof(*ngs->word_chan)); - ngs->word_lat_idx = ckd_calloc(dict_size(dict), - sizeof(*ngs->word_lat_idx)); - ngs->word_active = bitvec_alloc(dict_size(dict)); - ngs->last_ltrans = ckd_calloc(dict_size(dict), - sizeof(*ngs->last_ltrans)); - - /* FIXME: All these structures need to be made dynamic with - * garbage collection. */ - ngs->bp_table_size = cmd_ln_int32_r(config, "-latsize"); - ngs->bp_table = ckd_calloc(ngs->bp_table_size, - sizeof(*ngs->bp_table)); - /* FIXME: This thing is frickin' huge. */ - ngs->bscore_stack_size = ngs->bp_table_size * 20; - ngs->bscore_stack = ckd_calloc(ngs->bscore_stack_size, - sizeof(*ngs->bscore_stack)); - ngs->n_frame_alloc = 256; - ngs->bp_table_idx = ckd_calloc(ngs->n_frame_alloc + 1, - sizeof(*ngs->bp_table_idx)); - ++ngs->bp_table_idx; /* Make bptableidx[-1] valid */ - - /* Allocate active word list array */ - ngs->active_word_list = ckd_calloc_2d(2, dict_size(dict), - sizeof(**ngs->active_word_list)); - - ngs->lmset = ngram_model_set_init(config, &lm, &lmname, NULL, 1); - if (!ngs->lmset) - goto error_out; - - if (ngram_wid(ngs->lmset, S3_FINISH_WORD) == - ngram_unknown_wid(ngs->lmset)) - { - E_ERROR("Language model/set does not contain </s>, " - "recognition will fail\n"); - goto error_out; - } - - /* Create word mappings. */ - ngram_search_update_widmap(ngs); - - /* Initialize fwdtree, fwdflat, bestpath modules if necessary. */ - if (cmd_ln_boolean_r(config, "-fwdtree")) { - ngram_fwdtree_init(ngs); - ngs->fwdtree = TRUE; - ngs->fwdtree_perf.name = "fwdtree"; - ptmr_init(&ngs->fwdtree_perf); - } - if (cmd_ln_boolean_r(config, "-fwdflat")) { - ngram_fwdflat_init(ngs); - ngs->fwdflat = TRUE; - ngs->fwdflat_perf.name = "fwdflat"; - ptmr_init(&ngs->fwdflat_perf); - } - if (cmd_ln_boolean_r(config, "-bestpath")) { - ngs->bestpath = TRUE; - ngs->bestpath_perf.name = "bestpath"; - ptmr_init(&ngs->bestpath_perf); - } - - return (ps_search_t *)ngs; - -error_out: - ngram_search_free((ps_search_t *)ngs); - return NULL; -} - -static int -ngram_search_reinit(ps_search_t *search, dict_t *dict, dict2pid_t *d2p) -{ - ngram_search_t *ngs = (ngram_search_t *)search; - int old_n_words; - int rv = 0; - - /* Update the number of words. */ - old_n_words = search->n_words; - if (old_n_words != dict_size(dict)) { - search->n_words = dict_size(dict); - /* Reallocate these temporary arrays. */ - ckd_free(ngs->word_lat_idx); - ckd_free(ngs->word_active); - ckd_free(ngs->last_ltrans); - ckd_free_2d(ngs->active_word_list); - ngs->word_lat_idx = ckd_calloc(search->n_words, sizeof(*ngs->word_lat_idx)); - ngs->word_active = bitvec_alloc(search->n_words); - ngs->last_ltrans = ckd_calloc(search->n_words, sizeof(*ngs->last_ltrans)); - ngs->active_word_list - = ckd_calloc_2d(2, search->n_words, - sizeof(**ngs->active_word_list)); - } - - /* Free old dict2pid, dict */ - ps_search_base_reinit(search, dict, d2p); - - if (ngs->lmset == NULL) - return 0; - - /* Update beam widths. */ - ngram_search_calc_beams(ngs); - - /* Update word mappings. */ - ngram_search_update_widmap(ngs); - - /* Now rebuild lextrees. */ - if (ngs->fwdtree) { - if ((rv = ngram_fwdtree_reinit(ngs)) < 0) - return rv; - } - if (ngs->fwdflat) { - if ((rv = ngram_fwdflat_reinit(ngs)) < 0) - return rv; - } - - return rv; -} - -void -ngram_search_free(ps_search_t *search) -{ - ngram_search_t *ngs = (ngram_search_t *)search; - - ps_search_deinit(search); - if (ngs->fwdtree) - ngram_fwdtree_deinit(ngs); - if (ngs->fwdflat) - ngram_fwdflat_deinit(ngs); - if (ngs->bestpath) { - double n_speech = (double)ngs->n_tot_frame - / cmd_ln_int32_r(ps_search_config(ngs), "-frate"); - - E_INFO("TOTAL bestpath %.2f CPU %.3f xRT\n", - ngs->bestpath_perf.t_tot_cpu, - ngs->bestpath_perf.t_tot_cpu / n_speech); - E_INFO("TOTAL bestpath %.2f wall %.3f xRT\n", - ngs->bestpath_perf.t_tot_elapsed, - ngs->bestpath_perf.t_tot_elapsed / n_speech); - } - - hmm_context_free(ngs->hmmctx); - listelem_alloc_free(ngs->chan_alloc); - listelem_alloc_free(ngs->root_chan_alloc); - listelem_alloc_free(ngs->latnode_alloc); - ngram_model_free(ngs->lmset); - - ckd_free(ngs->word_chan); - ckd_free(ngs->word_lat_idx); - bitvec_free(ngs->word_active); - ckd_free(ngs->bp_table); - ckd_free(ngs->bscore_stack); - if (ngs->bp_table_idx != NULL) - ckd_free(ngs->bp_table_idx - 1); - ckd_free_2d(ngs->active_word_list); - ckd_free(ngs->last_ltrans); - ckd_free(ngs); -} - -int -ngram_search_mark_bptable(ngram_search_t *ngs, int frame_idx) -{ - if (frame_idx >= ngs->n_frame_alloc) { - ngs->n_frame_alloc *= 2; - ngs->bp_table_idx = ckd_realloc(ngs->bp_table_idx - 1, - (ngs->n_frame_alloc + 1) - * sizeof(*ngs->bp_table_idx)); - if (ngs->frm_wordlist) { - ngs->frm_wordlist = ckd_realloc(ngs->frm_wordlist, - ngs->n_frame_alloc - * sizeof(*ngs->frm_wordlist)); - } - ++ngs->bp_table_idx; /* Make bptableidx[-1] valid */ - } - ngs->bp_table_idx[frame_idx] = ngs->bpidx; - return ngs->bpidx; -} - -static void -set_real_wid(ngram_search_t *ngs, int32 bp) -{ - bptbl_t *ent, *prev; - - assert(bp != NO_BP); - ent = ngs->bp_table + bp; - if (ent->bp == NO_BP) - prev = NULL; - else - prev = ngs->bp_table + ent->bp; - - /* Propagate lm state for fillers, rotate it for words. */ - if (dict_filler_word(ps_search_dict(ngs), ent->wid)) { - if (prev != NULL) { - ent->real_wid = prev->real_wid; - ent->prev_real_wid = prev->prev_real_wid; - } - else { - ent->real_wid = dict_basewid(ps_search_dict(ngs), - ent->wid); - ent->prev_real_wid = BAD_S3WID; - } - } - else { - ent->real_wid = dict_basewid(ps_search_dict(ngs), ent->wid); - if (prev != NULL) - ent->prev_real_wid = prev->real_wid; - else - ent->prev_real_wid = BAD_S3WID; - } -} - -#define NGRAM_HISTORY_LONG_WORD 2000 /* 20s */ - -void -ngram_search_save_bp(ngram_search_t *ngs, int frame_idx, - int32 w, int32 score, int32 path, int32 rc) -{ - int32 bp; - - /* Look for an existing exit for this word in this frame. The - * only reason one would exist is from a different right context - * triphone, but of course that happens quite frequently. */ - bp = ngs->word_lat_idx[w]; - if (bp != NO_BP) { - - if (frame_idx - ngs->bp_table[path].frame > NGRAM_HISTORY_LONG_WORD) { - E_WARN("Word '%s' survived for %d frames, potential overpruning\n", dict_wordstr(ps_search_dict(ngs), w), - frame_idx - ngs->bp_table[path].frame); - } - - /* Keep only the best scoring one, we will reconstruct the - * others from the right context scores - usually the history - * is not lost. */ - if (ngs->bp_table[bp].score WORSE_THAN score) { - assert(path != bp); /* Pathological. */ - if (ngs->bp_table[bp].bp != path) { - int32 bplh[2], newlh[2]; - /* But, sometimes, the history *is* lost. If we wanted to - * do exact language model scoring we'd have to preserve - * these alternate histories. */ - E_DEBUG(2,("Updating path history %d => %d frame %d\n", - ngs->bp_table[bp].bp, path, frame_idx)); - bplh[0] = ngs->bp_table[bp].bp == -1 - ? -1 : ngs->bp_table[ngs->bp_table[bp].bp].prev_real_wid; - bplh[1] = ngs->bp_table[bp].bp == -1 - ? -1 : ngs->bp_table[ngs->bp_table[bp].bp].real_wid; - newlh[0] = path == -1 - ? -1 : ngs->bp_table[path].prev_real_wid; - newlh[1] = path == -1 - ? -1 : ngs->bp_table[path].real_wid; - /* Actually it's worth checking how often the actual - * language model state changes. */ - if (bplh[0] != newlh[0] || bplh[1] != newlh[1]) { - /* It's fairly rare that the actual language model - * state changes, but it does happen some - * times. */ - E_DEBUG(1, ("Updating language model state %s,%s => %s,%s frame %d\n", - dict_wordstr(ps_search_dict(ngs), bplh[0]), - dict_wordstr(ps_search_dict(ngs), bplh[1]), - dict_wordstr(ps_search_dict(ngs), newlh[0]), - dict_wordstr(ps_search_dict(ngs), newlh[1]), - frame_idx)); - set_real_wid(ngs, bp); - } - ngs->bp_table[bp].bp = path; - } - ngs->bp_table[bp].score = score; - } - /* But do keep track of scores for all right contexts, since - * we need them to determine the starting path scores for any - * successors of this word exit. */ - if (ngs->bp_table[bp].s_idx != -1) - ngs->bscore_stack[ngs->bp_table[bp].s_idx + rc] = score; - } - else { - int32 i, rcsize; - bptbl_t *be; - - /* This might happen if recognition fails. */ - if (ngs->bpidx == NO_BP) { - E_ERROR("No entries in backpointer table!"); - return; - } - - /* Expand the backpointer tables if necessary. */ - if (ngs->bpidx >= ngs->bp_table_size) { - ngs->bp_table_size *= 2; - ngs->bp_table = ckd_realloc(ngs->bp_table, - ngs->bp_table_size - * sizeof(*ngs->bp_table)); - E_INFO("Resized backpointer table to %d entries\n", ngs->bp_table_size); - } - if (ngs->bss_head >= ngs->bscore_stack_size - - bin_mdef_n_ciphone(ps_search_acmod(ngs)->mdef)) { - ngs->bscore_stack_size *= 2; - ngs->bscore_stack = ckd_realloc(ngs->bscore_stack, - ngs->bscore_stack_size - * sizeof(*ngs->bscore_stack)); - E_INFO("Resized score stack to %d entries\n", ngs->bscore_stack_size); - } - - ngs->word_lat_idx[w] = ngs->bpidx; - be = &(ngs->bp_table[ngs->bpidx]); - be->wid = w; - be->frame = frame_idx; - be->bp = path; - be->score = score; - be->s_idx = ngs->bss_head; - be->valid = TRUE; - assert(path != ngs->bpidx); - - /* DICT2PID */ - /* Get diphone ID for final phone and number of ssids corresponding to it. */ - be->last_phone = dict_last_phone(ps_search_dict(ngs),w); - if (dict_is_single_phone(ps_search_dict(ngs), w)) { - be->last2_phone = -1; - be->s_idx = -1; - rcsize = 0; - } - else { - be->last2_phone = dict_second_last_phone(ps_search_dict(ngs),w); - rcsize = dict2pid_rssid(ps_search_dict2pid(ngs), - be->last_phone, be->last2_phone)->n_ssid; - } - /* Allocate some space on the bscore_stack for all of these triphones. */ - for (i = 0; i < rcsize; ++i) - ngs->bscore_stack[ngs->bss_head + i] = WORST_SCORE; - if (rcsize) - ngs->bscore_stack[ngs->bss_head + rc] = score; - set_real_wid(ngs, ngs->bpidx); - - ngs->bpidx++; - ngs->bss_head += rcsize; - } -} - -int -ngram_search_find_exit(ngram_search_t *ngs, int frame_idx, int32 *out_best_score, int32 *out_is_final) -{ - /* End of backpointers for this frame. */ - int end_bpidx; - int best_exit, bp; - int32 best_score; - - /* No hypothesis means no exit node! */ - if (ngs->n_frame == 0) - return NO_BP; - - if (frame_idx == -1 || frame_idx >= ngs->n_frame) - frame_idx = ngs->n_frame - 1; - end_bpidx = ngs->bp_table_idx[frame_idx]; - - best_score = WORST_SCORE; - best_exit = NO_BP; - - /* Scan back to find a frame with some backpointers in it. */ - while (frame_idx >= 0 && ngs->bp_table_idx[frame_idx] == end_bpidx) - --frame_idx; - /* This is NOT an error, it just means there is no hypothesis yet. */ - if (frame_idx < 0) - return NO_BP; - - /* Now find the entry for </s> OR the best scoring entry. */ - assert(end_bpidx < ngs->bp_table_size); - for (bp = ngs->bp_table_idx[frame_idx]; bp < end_bpidx; ++bp) { - if (ngs->bp_table[bp].wid == ps_search_finish_wid(ngs) - || ngs->bp_table[bp].score BETTER_THAN best_score) { - best_score = ngs->bp_table[bp].score; - best_exit = bp; - } - if (ngs->bp_table[bp].wid == ps_search_finish_wid(ngs)) - break; - } - - if (out_best_score) { - *out_best_score = best_score; - } - if (out_is_final) { - *out_is_final = (ngs->bp_table[bp].wid == ps_search_finish_wid(ngs)); - } - return best_exit; -} - -char const * -ngram_search_bp_hyp(ngram_search_t *ngs, int bpidx) -{ - ps_search_t *base = ps_search_base(ngs); - char *c; - size_t len; - int bp; - - if (bpidx == NO_BP) - return NULL; - - bp = bpidx; - len = 0; - while (bp != NO_BP) { - bptbl_t *be = &ngs->bp_table[bp]; - bp = be->bp; - if (dict_real_word(ps_search_dict(ngs), be->wid)) - len += strlen(dict_basestr(ps_search_dict(ngs), be->wid)) + 1; - } - - ckd_free(base->hyp_str); - if (len == 0) { - base->hyp_str = NULL; - return base->hyp_str; - } - base->hyp_str = ckd_calloc(1, len); - - bp = bpidx; - c = base->hyp_str + len - 1; - while (bp != NO_BP) { - bptbl_t *be = &ngs->bp_table[bp]; - size_t len; - - bp = be->bp; - if (dict_real_word(ps_search_dict(ngs), be->wid)) { - len = strlen(dict_basestr(ps_search_dict(ngs), be->wid)); - c -= len; - memcpy(c, dict_basestr(ps_search_dict(ngs), be->wid), len); - if (c > base->hyp_str) { - --c; - *c = ' '; - } - } - } - - return base->hyp_str; -} - -void -ngram_search_alloc_all_rc(ngram_search_t *ngs, int32 w) -{ - chan_t *hmm, *thmm; - xwdssid_t *rssid; - int32 i, tmatid, ciphone; - - /* DICT2PID */ - /* Get pointer to array of triphones for final diphone. */ - assert(!dict_is_single_phone(ps_search_dict(ngs), w)); - ciphone = dict_last_phone(ps_search_dict(ngs),w); - rssid = dict2pid_rssid(ps_search_dict2pid(ngs), - ciphone, - dict_second_last_phone(ps_search_dict(ngs),w)); - tmatid = bin_mdef_pid2tmatid(ps_search_acmod(ngs)->mdef, ciphone); - hmm = ngs->word_chan[w]; - if ((hmm == NULL) || (hmm_nonmpx_ssid(&hmm->hmm) != rssid->ssid[0])) { - hmm = listelem_malloc(ngs->chan_alloc); - hmm->next = ngs->word_chan[w]; - ngs->word_chan[w] = hmm; - - hmm->info.rc_id = 0; - hmm->ciphone = ciphone; - hmm_init(ngs->hmmctx, &hmm->hmm, FALSE, rssid->ssid[0], tmatid); - E_DEBUG(3,("allocated rc_id 0 ssid %d ciphone %d lc %d word %s\n", - rssid->ssid[0], hmm->ciphone, - dict_second_last_phone(ps_search_dict(ngs),w), - dict_wordstr(ps_search_dict(ngs),w))); - } - for (i = 1; i < rssid->n_ssid; ++i) { - if ((hmm->next == NULL) || (hmm_nonmpx_ssid(&hmm->next->hmm) != rssid->ssid[i])) { - thmm = listelem_malloc(ngs->chan_alloc); - thmm->next = hmm->next; - hmm->next = thmm; - hmm = thmm; - - hmm->info.rc_id = i; - hmm->ciphone = ciphone; - hmm_init(ngs->hmmctx, &hmm->hmm, FALSE, rssid->ssid[i], tmatid); - E_DEBUG(3,("allocated rc_id %d ssid %d ciphone %d lc %d word %s\n", - i, rssid->ssid[i], hmm->ciphone, - dict_second_last_phone(ps_search_dict(ngs),w), - dict_wordstr(ps_search_dict(ngs),w))); - } - else - hmm = hmm->next; - } -} - -void -ngram_search_free_all_rc(ngram_search_t *ngs, int32 w) -{ - chan_t *hmm, *thmm; - - for (hmm = ngs->word_chan[w]; hmm; hmm = thmm) { - thmm = hmm->next; - hmm_deinit(&hmm->hmm); - listelem_free(ngs->chan_alloc, hmm); - } - ngs->word_chan[w] = NULL; -} - -int32 -ngram_search_exit_score(ngram_search_t *ngs, bptbl_t *pbe, int rcphone) -{ - /* DICT2PID */ - /* Get the mapping from right context phone ID to index in the - * right context table and the bscore_stack. */ - if (pbe->last2_phone == -1) { - /* No right context for single phone predecessor words. */ - return pbe->score; - } - else { - xwdssid_t *rssid; - /* Find the index for the last diphone of the previous word + - * the first phone of the current word. */ - rssid = dict2pid_rssid(ps_search_dict2pid(ngs), - pbe->last_phone, pbe->last2_phone); - /* This may be WORST_SCORE, which means that there was no exit - * with rcphone as right context. */ - return ngs->bscore_stack[pbe->s_idx + rssid->cimap[rcphone]]; - } -} - -/* - * Compute acoustic and LM scores for a BPTable entry (segment). - */ -void -ngram_compute_seg_score(ngram_search_t *ngs, bptbl_t *be, float32 lwf, - int32 *out_ascr, int32 *out_lscr) -{ - bptbl_t *pbe; - int32 start_score; - - /* Start of utterance. */ - if (be->bp == NO_BP) { - *out_ascr = be->score; - *out_lscr = 0; - return; - } - - /* Otherwise, calculate lscr and ascr. */ - pbe = ngs->bp_table + be->bp; - start_score = ngram_search_exit_score(ngs, pbe, - dict_first_phone(ps_search_dict(ngs),be->wid)); - assert(start_score BETTER_THAN WORST_SCORE); - - /* FIXME: These result in positive acoustic scores when filler - words have non-filler pronunciations. That whole business - is still pretty much broken but at least it doesn't - segfault. */ - if (be->wid == ps_search_silence_wid(ngs)) { - *out_lscr = ngs->silpen; - } - else if (dict_filler_word(ps_search_dict(ngs), be->wid)) { - *out_lscr = ngs->fillpen; - } - else { - int32 n_used; - *out_lscr = ngram_tg_score(ngs->lmset, - be->real_wid, - pbe->real_wid, - pbe->prev_real_wid, - &n_used)>>SENSCR_SHIFT; - *out_lscr = *out_lscr * lwf; - } - *out_ascr = be->score - start_score - *out_lscr; -} - -static int -ngram_search_start(ps_search_t *search) -{ - ngram_search_t *ngs = (ngram_search_t *)search; - - ngs->done = FALSE; - ngram_model_flush(ngs->lmset); - if (ngs->fwdtree) - ngram_fwdtree_start(ngs); - else if (ngs->fwdflat) - ngram_fwdflat_start(ngs); - else - return -1; - return 0; -} - -static int -ngram_search_step(ps_search_t *search, int frame_idx) -{ - ngram_search_t *ngs = (ngram_search_t *)search; - - if (ngs->fwdtree) - return ngram_fwdtree_search(ngs, frame_idx); - else if (ngs->fwdflat) - return ngram_fwdflat_search(ngs, frame_idx); - else - return -1; -} - -void -dump_bptable(ngram_search_t *ngs) -{ - int i; - E_INFO("Backpointer table (%d entries):\n", ngs->bpidx); - for (i = 0; i < ngs->bpidx; ++i) { - bptbl_t *bpe = ngs->bp_table + i; - int j, rcsize; - - E_INFO_NOFN("%-5d %-10s start %-3d end %-3d score %-8d bp %-3d real_wid %-5d prev_real_wid %-5d", - i, dict_wordstr(ps_search_dict(ngs), bpe->wid), - (bpe->bp == -1 - ? 0 : ngs->bp_table[bpe->bp].frame + 1), - bpe->frame, bpe->score, bpe->bp, - bpe->real_wid, bpe->prev_real_wid); - - if (bpe->last2_phone == -1) - rcsize = 0; - else - rcsize = dict2pid_rssid(ps_search_dict2pid(ngs), - bpe->last_phone, bpe->last2_phone)->n_ssid; - if (rcsize) { - E_INFOCONT("\tbss"); - for (j = 0; j < rcsize; ++j) - if (ngs->bscore_stack[bpe->s_idx + j] != WORST_SCORE) - E_INFOCONT(" %d", bpe->score - ngs->bscore_stack[bpe->s_idx + j]); - } - E_INFOCONT("\n"); - } -} - -static int -ngram_search_finish(ps_search_t *search) -{ - ngram_search_t *ngs = (ngram_search_t *)search; - - ngs->n_tot_frame += ngs->n_frame; - if (ngs->fwdtree) { - ngram_fwdtree_finish(ngs); - /* dump_bptable(ngs); */ - - /* Now do fwdflat search in its entirety, if requested. */ - if (ngs->fwdflat) { - int i; - /* Rewind the acoustic model. */ - if (acmod_rewind(ps_search_acmod(ngs)) < 0) - return -1; - /* Now redo search. */ - ngram_fwdflat_start(ngs); - i = 0; - while (ps_search_acmod(ngs)->n_feat_frame > 0) { - int nfr; - if ((nfr = ngram_fwdflat_search(ngs, i)) < 0) - return nfr; - acmod_advance(ps_search_acmod(ngs)); - ++i; - } - ngram_fwdflat_finish(ngs); - /* And now, we should have a result... */ - /* dump_bptable(ngs); */ - } - } - else if (ngs->fwdflat) { - ngram_fwdflat_finish(ngs); - } - - /* Mark the current utterance as done. */ - ngs->done = TRUE; - return 0; -} - -static ps_latlink_t * -ngram_search_bestpath(ps_search_t *search, int32 *out_score, int backward) -{ - ngram_search_t *ngs = (ngram_search_t *)search; - - if (search->last_link == NULL) { - search->last_link = ps_lattice_bestpath(search->dag, ngs->lmset, - ngs->bestpath_fwdtree_lw_ratio, - ngs->ascale); - if (search->last_link == NULL) - return NULL; - /* Also calculate betas so we can fill in the posterior - * probability field in the segmentation. */ - if (search->post == 0) - search->post = ps_lattice_posterior(search->dag, ngs->lmset, - ngs->ascale); - } - if (out_score) - *out_score = search->last_link->path_scr + search->dag->final_node_ascr; - return search->last_link; -} - -static char const * -ngram_search_hyp(ps_search_t *search, int32 *out_score, int32 *out_is_final) -{ - ngram_search_t *ngs = (ngram_search_t *)search; - - /* Only do bestpath search if the utterance is complete. */ - if (ngs->bestpath && ngs->done) { - ps_lattice_t *dag; - ps_latlink_t *link; - char const *hyp; - double n_speech; - - ptmr_reset(&ngs->bestpath_perf); - ptmr_start(&ngs->bestpath_perf); - if ((dag = ngram_search_lattice(search)) == NULL) - return NULL; - if ((link = ngram_search_bestpath(search, out_score, FALSE)) == NULL) - return NULL; - hyp = ps_lattice_hyp(dag, link); - ptmr_stop(&ngs->bestpath_perf); - n_speech = (double)dag->n_frames - / cmd_ln_int32_r(ps_search_config(ngs), "-frate"); - E_INFO("bestpath %.2f CPU %.3f xRT\n", - ngs->bestpath_perf.t_cpu, - ngs->bestpath_perf.t_cpu / n_speech); - E_INFO("bestpath %.2f wall %.3f xRT\n", - ngs->bestpath_perf.t_elapsed, - ngs->bestpath_perf.t_elapsed / n_speech); - return hyp; - } - else { - int32 bpidx; - - /* fwdtree and fwdflat use same backpointer table. */ - bpidx = ngram_search_find_exit(ngs, -1, out_score, out_is_final); - if (bpidx != NO_BP) - return ngram_search_bp_hyp(ngs, bpidx); - } - - return NULL; -} - -static void -ngram_search_bp2itor(ps_seg_t *seg, int bp) -{ - ngram_search_t *ngs = (ngram_search_t *)seg->search; - bptbl_t *be, *pbe; - - be = &ngs->bp_table[bp]; - pbe = be->bp == -1 ? NULL : &ngs->bp_table[be->bp]; - seg->word = dict_wordstr(ps_search_dict(ngs), be->wid); - seg->ef = be->frame; - seg->sf = pbe ? pbe->frame + 1 : 0; - seg->prob = 0; /* Bogus value... */ - /* Compute acoustic and LM scores for this segment. */ - if (pbe == NULL) { - seg->ascr = be->score; - seg->lscr = 0; - seg->lback = 0; - } - else { - int32 start_score; - - /* Find ending path score of previous word. */ - start_score = ngram_search_exit_score(ngs, pbe, - dict_first_phone(ps_search_dict(ngs), be->wid)); - assert(start_score BETTER_THAN WORST_SCORE); - if (be->wid == ps_search_silence_wid(ngs)) { - seg->lscr = ngs->silpen; - } - else if (dict_filler_word(ps_search_dict(ngs), be->wid)) { - seg->lscr = ngs->fillpen; - } - else { - seg->lscr = ngram_tg_score(ngs->lmset, - be->real_wid, - pbe->real_wid, - pbe->prev_real_wid, - &seg->lback)>>SENSCR_SHIFT; - seg->lscr = (int32)(seg->lscr * seg->lwf); - } - seg->ascr = be->score - start_score - seg->lscr; - } -} - -static void -ngram_bp_seg_free(ps_seg_t *seg) -{ - bptbl_seg_t *itor = (bptbl_seg_t *)seg; - - ckd_free(itor->bpidx); - ckd_free(itor); -} - -static ps_seg_t * -ngram_bp_seg_next(ps_seg_t *seg) -{ - bptbl_seg_t *itor = (bptbl_seg_t *)seg; - - if (++itor->cur == itor->n_bpidx) { - ngram_bp_seg_free(seg); - return NULL; - } - - ngram_search_bp2itor(seg, itor->bpidx[itor->cur]); - return seg; -} - -static ps_segfuncs_t ngram_bp_segfuncs = { - /* seg_next */ ngram_bp_seg_next, - /* seg_free */ ngram_bp_seg_free -}; - -static ps_seg_t * -ngram_search_bp_iter(ngram_search_t *ngs, int bpidx, float32 lwf) -{ - bptbl_seg_t *itor; - int bp, cur; - - /* Calling this an "iterator" is a bit of a misnomer since we have - * to get the entire backtrace in order to produce it. On the - * other hand, all we actually need is the bptbl IDs, and we can - * allocate a fixed-size array of them. */ - itor = ckd_calloc(1, sizeof(*itor)); - itor->base.vt = &ngram_bp_segfuncs; - itor->base.search = ps_search_base(ngs); - itor->base.lwf = lwf; - itor->n_bpidx = 0; - bp = bpidx; - while (bp != NO_BP) { - bptbl_t *be = &ngs->bp_table[bp]; - bp = be->bp; - ++itor->n_bpidx; - } - if (itor->n_bpidx == 0) { - ckd_free(itor); - return NULL; - } - itor->bpidx = ckd_calloc(itor->n_bpidx, sizeof(*itor->bpidx)); - cur = itor->n_bpidx - 1; - bp = bpidx; - while (bp != NO_BP) { - bptbl_t *be = &ngs->bp_table[bp]; - itor->bpidx[cur] = bp; - bp = be->bp; - --cur; - } - - /* Fill in relevant fields for first element. */ - ngram_search_bp2itor((ps_seg_t *)itor, itor->bpidx[0]); - - return (ps_seg_t *)itor; -} - -static ps_seg_t * -ngram_search_seg_iter(ps_search_t *search, int32 *out_score) -{ - ngram_search_t *ngs = (ngram_search_t *)search; - - /* Only do bestpath search if the utterance is done. */ - if (ngs->bestpath && ngs->done) { - ps_lattice_t *dag; - ps_latlink_t *link; - double n_speech; - ps_seg_t *itor; - - ptmr_reset(&ngs->bestpath_perf); - ptmr_start(&ngs->bestpath_perf); - if ((dag = ngram_search_lattice(search)) == NULL) - return NULL; - if ((link = ngram_search_bestpath(search, out_score, TRUE)) == NULL) - return NULL; - itor = ps_lattice_seg_iter(dag, link, - ngs->bestpath_fwdtree_lw_ratio); - ptmr_stop(&ngs->bestpath_perf); - n_speech = (double)dag->n_frames - / cmd_ln_int32_r(ps_search_config(ngs), "-frate"); - E_INFO("bestpath %.2f CPU %.3f xRT\n", - ngs->bestpath_perf.t_cpu, - ngs->bestpath_perf.t_cpu / n_speech); - E_INFO("bestpath %.2f wall %.3f xRT\n", - ngs->bestpath_perf.t_elapsed, - ngs->bestpath_perf.t_elapsed / n_speech); - return itor; - } - else { - int32 bpidx; - - /* fwdtree and fwdflat use same backpointer table. */ - bpidx = ngram_search_find_exit(ngs, -1, out_score, NULL); - return ngram_search_bp_iter(ngs, bpidx, - /* but different language weights... */ - (ngs->done && ngs->fwdflat) - ? ngs->fwdflat_fwdtree_lw_ratio : 1.0); - } - - return NULL; -} - -static int32 -ngram_search_prob(ps_search_t *search) -{ - ngram_search_t *ngs = (ngram_search_t *)search; - - /* Only do bestpath search if the utterance is done. */ - if (ngs->bestpath && ngs->done) { - ps_lattice_t *dag; - ps_latlink_t *link; - - if ((dag = ngram_search_lattice(search)) == NULL) - return 0; - if ((link = ngram_search_bestpath(search, NULL, TRUE)) == NULL) - return 0; - return search->post; - } - else { - /* FIXME: Give some kind of good estimate here, eventually. */ - return 0; - } -} - -static void -create_dag_nodes(ngram_search_t *ngs, ps_lattice_t *dag) -{ - bptbl_t *bp_ptr; - int32 i; - - for (i = 0, bp_ptr = ngs->bp_table; i < ngs->bpidx; ++i, ++bp_ptr) { - int32 sf, ef, wid; - ps_latnode_t *node; - - /* Skip invalid backpointers (these result from -maxwpf pruning) */ - if (!bp_ptr->valid) - continue; - - sf = (bp_ptr->bp < 0) ? 0 : ngs->bp_table[bp_ptr->bp].frame + 1; - ef = bp_ptr->frame; - wid = bp_ptr->wid; - - assert(ef < dag->n_frames); - /* Skip non-final </s> entries. */ - if ((wid == ps_search_finish_wid(ngs)) && (ef < dag->n_frames - 1)) - continue; - - /* Skip if word not in LM */ - if ((!dict_filler_word(ps_search_dict(ngs), wid)) - && (!ngram_model_set_known_wid(ngs->lmset, - dict_basewid(ps_search_dict(ngs), wid)))) - continue; - - /* See if bptbl entry <wid,sf> already in lattice */ - for (node = dag->nodes; node; node = node->next) { - if ((node->wid == wid) && (node->sf == sf)) - break; - } - - /* For the moment, store bptbl indices in node.{fef,lef} */ - if (node) - node->lef = i; - else { - /* New node; link to head of list */ - node = listelem_malloc(dag->latnode_alloc); - node->wid = wid; - node->sf = sf; /* This is a frame index. */ - node->fef = node->lef = i; /* These are backpointer indices (argh) */ - node->reachable = FALSE; - node->entries = NULL; - node->exits = NULL; - - /* NOTE: This creates the list of nodes in reverse - * topological order, i.e. a node always precedes its - * antecedents in this list. */ - node->next = dag->nodes; - dag->nodes = node; - ++dag->n_nodes; - } - } -} - -static ps_latnode_t * -find_start_node(ngram_search_t *ngs, ps_lattice_t *dag) -{ - ps_latnode_t *node; - - /* Find start node <s>.0 */ - for (node = dag->nodes; node; node = node->next) { - if ((node->wid == ps_search_start_wid(ngs)) && (node->sf == 0)) - break; - } - if (!node) { - /* This is probably impossible. */ - E_ERROR("Couldn't find <s> in first frame\n"); - return NULL; - } - return node; -} - -static ps_latnode_t * -find_end_node(ngram_search_t *ngs, ps_lattice_t *dag, float32 lwf) -{ - ps_latnode_t *node; - int32 ef, bestbp, bp, bestscore; - - /* Find final node </s>.last_frame; nothing can follow this node */ - for (node = dag->nodes; node; node = node->next) { - int32 lef = ngs->bp_table[node->lef].frame; - if ((node->wid == ps_search_finish_wid(ngs)) - && (lef == dag->n_frames - 1)) - break; - } - if (node != NULL) - return node; - - /* It is quite likely that no </s> exited in the last frame. So, - * find the node corresponding to the best exit. */ - /* Find the last frame containing a word exit. */ - for (ef = dag->n_frames - 1; - ef >= 0 && ngs->bp_table_idx[ef] == ngs->bpidx; - --ef); - if (ef < 0) { - E_ERROR("Empty backpointer table: can not build DAG.\n"); - return NULL; - } - - /* Find best word exit in that frame. */ - bestscore = WORST_SCORE; - bestbp = NO_BP; - for (bp = ngs->bp_table_idx[ef]; bp < ngs->bp_table_idx[ef + 1]; ++bp) { - int32 n_used, l_scr, wid, prev_wid; - wid = ngs->bp_table[bp].real_wid; - prev_wid = ngs->bp_table[bp].prev_real_wid; - /* Always prefer </s>, of which there will only be one per frame. */ - if (wid == ps_search_finish_wid(ngs)) { - bestbp = bp; - break; - } - l_scr = ngram_tg_score(ngs->lmset, ps_search_finish_wid(ngs), - wid, prev_wid, &n_used) >>SENSCR_SHIFT; - l_scr = l_scr * lwf; - if (ngs->bp_table[bp].score + l_scr BETTER_THAN bestscore) { - bestscore = ngs->bp_table[bp].score + l_scr; - bestbp = bp; - } - } - if (bestbp == NO_BP) { - E_ERROR("No word exits found in last frame (%d), assuming no recognition\n", ef); - return NULL; - } - E_INFO("</s> not found in last frame, using %s.%d instead\n", - dict_basestr(ps_search_dict(ngs), ngs->bp_table[bestbp].wid), ef); - - /* Now find the node that corresponds to it. */ - for (node = dag->nodes; node; node = node->next) { - if (node->lef == bestbp) - return node; - } - - /* FIXME: This seems to happen a lot! */ - E_ERROR("Failed to find DAG node corresponding to %s\n", - dict_basestr(ps_search_dict(ngs), ngs->bp_table[bestbp].wid)); - return NULL; -} - -/* - * Build lattice from bptable. - */ -ps_lattice_t * -ngram_search_lattice(ps_search_t *search) -{ - int32 i, score, ascr, lscr; - ps_latnode_t *node, *from, *to; - ngram_search_t *ngs; - ps_lattice_t *dag; - int min_endfr, nlink; - float lwf; - - ngs = (ngram_search_t *)search; - min_endfr = cmd_ln_int32_r(ps_search_config(search), "-min_endfr"); - - /* If the best score is WORST_SCORE or worse, there is no way to - * make a lattice. */ - if (ngs->best_score == WORST_SCORE || ngs->best_score WORSE_THAN WORST_SCORE) - return NULL; - - /* Check to see if a lattice has previously been created over the - * same number of frames, and reuse it if so. */ - if (search->dag && search->dag->n_frames == ngs->n_frame) - return search->dag; - - /* Nope, create a new one. */ - ps_lattice_free(search->dag); - search->dag = NULL; - dag = ps_lattice_init_search(search, ngs->n_frame); - /* Compute these such that they agree with the fwdtree language weight. */ - lwf = ngs->fwdflat ? ngs->fwdflat_fwdtree_lw_ratio : 1.0; - create_dag_nodes(ngs, dag); - if ((dag->start = find_start_node(ngs, dag)) == NULL) - goto error_out; - if ((dag->end = find_end_node(ngs, dag, ngs->bestpath_fwdtree_lw_ratio)) == NULL) - goto error_out; - E_INFO("lattice start node %s.%d end node %s.%d\n", - dict_wordstr(search->dict, dag->start->wid), dag->start->sf, - dict_wordstr(search->dict, dag->end->wid), dag->end->sf); - - ngram_compute_seg_score(ngs, ngs->bp_table + dag->end->lef, lwf, - &dag->final_node_ascr, &lscr); - - /* - * At this point, dag->nodes is ordered such that nodes earlier in - * the list can follow (in time) those later in the list, but not - * vice versa (see above - also note that adjacency is purely - * determined by time which is why we can make this claim). Now - * create precedence links and simultanesously mark all nodes that - * can reach dag->end. (All nodes are reached from dag->start - * simply by definition - they were created that way). - * - * Note that this also means that any nodes before dag->end in the - * list can be discarded, meaning that dag->end will always be - * equal to dag->nodes (FIXME: except when loading from a file but - * we can fix that...) - */ - i = 0; - while (dag->nodes && dag->nodes != dag->end) { - ps_latnode_t *next = dag->nodes->next; - listelem_free(dag->latnode_alloc, dag->nodes); - dag->nodes = next; - ++i; - } - E_INFO("Eliminated %d nodes before end node\n", i); - dag->end->reachable = TRUE; - nlink = 0; - for (to = dag->end; to; to = to->next) { - int fef, lef; - - /* Skip if not reachable; it will never be reachable from dag->end */ - if (!to->reachable) - continue; - - /* Prune nodes with too few endpoints - heuristic - borrowed from Sphinx3 */ - fef = ngs->bp_table[to->fef].frame; - lef = ngs->bp_table[to->lef].frame; - if (to != dag->end && lef - fef < min_endfr) { - to->reachable = FALSE; - continue; - } - - /* Find predecessors of to : from->fef+1 <= to->sf <= from->lef+1 */ - for (from = to->next; from; from = from->next) { - bptbl_t *from_bpe; - - fef = ngs->bp_table[from->fef].frame; - lef = ngs->bp_table[from->lef].frame; - - if ((to->sf <= fef) || (to->sf > lef + 1)) - continue; - if (lef - fef < min_endfr) { - assert(!from->reachable); - continue; - } - - /* Find bptable entry for "from" that exactly precedes "to" */ - i = from->fef; - from_bpe = ngs->bp_table + i; - for (; i <= from->lef; i++, from_bpe++) { - if (from_bpe->wid != from->wid) - continue; - if (from_bpe->frame >= to->sf - 1) - break; - } - - if ((i > from->lef) || (from_bpe->frame != to->sf - 1)) - continue; - - /* Find acoustic score from.sf->to.sf-1 with right context = to */ - /* This gives us from_bpe's best acoustic score. */ - ngram_compute_seg_score(ngs, from_bpe, lwf, - &ascr, &lscr); - /* Now find the exact path score for from->to, including - * the appropriate final triphone. In fact this might not - * exist. */ - score = ngram_search_exit_score(ngs, from_bpe, - dict_first_phone(ps_search_dict(ngs), to->wid)); - /* Does not exist. Can't create a link here. */ - if (score == WORST_SCORE) - continue; - /* Adjust the arc score to match the correct triphone. */ - else - score = ascr + (score - from_bpe->score); - if (score BETTER_THAN 0) { - /* Scores must be negative, or Bad Things will happen. - In general, they are, except in corner cases - involving filler words. We don't want to throw any - links away so we'll keep these, but with some - arbitrarily improbable but recognizable score. */ - ps_lattice_link(dag, from, to, -424242, from_bpe->frame); - ++nlink; - from->reachable = TRUE; - } - else if (score BETTER_THAN WORST_SCORE) { - ps_lattice_link(dag, from, to, score, from_bpe->frame); - ++nlink; - from->reachable = TRUE; - } - } - } - - /* There must be at least one path between dag->start and dag->end */ - if (!dag->start->reachable) { - E_ERROR("End node of lattice isolated; unreachable\n"); - goto error_out; - } - - for (node = dag->nodes; node; node = node->next) { - /* Change node->{fef,lef} from bptbl indices to frames. */ - node->fef = ngs->bp_table[node->fef].frame; - node->lef = ngs->bp_table[node->lef].frame; - /* Find base wid for nodes. */ - node->basewid = dict_basewid(search->dict, node->wid); - } - - /* Link nodes with alternate pronunciations at the same timepoint. */ - for (node = dag->nodes; node; node = node->next) { - ps_latnode_t *alt; - /* Scan forward to find the next alternate, then stop. */ - for (alt = node->next; alt && alt->sf == node->sf; alt = alt->next) { - if (alt->basewid == node->basewid) { - alt->alt = node->alt; - node->alt = alt; - break; - } - } - } - E_INFO("Lattice has %d nodes, %d links\n", dag->n_nodes, nlink); - - /* Minor hack: If the final node is a filler word and not </s>, - * then set its base word ID to </s>, so that the language model - * scores won't be screwed up. */ - if (dict_filler_word(ps_search_dict(ngs), dag->end->wid)) - dag->end->basewid = ps_search_finish_wid(ngs); - - /* Free nodes unreachable from dag->end and their links */ - ps_lattice_delete_unreachable(dag); - - /* Add silprob and fillprob to corresponding links */ - ps_lattice_penalize_fillers(dag, ngs->silpen, ngs->fillpen); - - search->dag = dag; - return dag; - -error_out: - ps_lattice_free(dag); - return NULL; -} - -void ngram_search_set_lm(ngram_model_t *lm) -{ - default_lm = ngram_model_retain(lm); -} - |