/* -*- 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 ps_lattice.h Word graph search */ #ifndef __PS_LATTICE_H__ #define __PS_LATTICE_H__ /* SphinxBase headers. */ #include #include /* PocketSphinx headers. */ #include /** * Word graph structure used in bestpath/nbest search. */ typedef struct ps_lattice_s ps_lattice_t; /** * DAG nodes. * * A node corresponds to a number of hypothesized instances of a word * which all share the same starting point. */ typedef struct ps_latnode_s ps_latnode_t; /** * Iterator over DAG nodes. */ typedef struct ps_latnode_s ps_latnode_iter_t; /* pay no attention to the man behind the curtain */ /** * Links between DAG nodes. * * A link corresponds to a single hypothesized instance of a word with * a given start and end point. */ typedef struct ps_latlink_s ps_latlink_t; /** * Iterator over DAG links. */ typedef struct latlink_list_s ps_latlink_iter_t; /* Forward declaration needed to avoid circular includes */ struct ps_decoder_s; /** * Read a lattice from a file on disk. * * @param ps Decoder to use for processing this lattice, or NULL. * @param file Path to lattice file. * @return Newly created lattice, or NULL for failure. */ POCKETSPHINX_EXPORT ps_lattice_t *ps_lattice_read(struct ps_decoder_s *ps, char const *file); /** * Retain a lattice. * * This function retains ownership of a lattice for the caller, * preventing it from being freed automatically. You must call * ps_lattice_free() to free it after having called this function. * * @return pointer to the retained lattice. */ POCKETSPHINX_EXPORT ps_lattice_t *ps_lattice_retain(ps_lattice_t *dag); /** * Free a lattice. * * @return new reference count (0 if dag was freed) */ POCKETSPHINX_EXPORT int ps_lattice_free(ps_lattice_t *dag); /** * Write a lattice to disk. * * @return 0 for success, <0 on failure. */ POCKETSPHINX_EXPORT int ps_lattice_write(ps_lattice_t *dag, char const *filename); /** * Write a lattice to disk in HTK format * * @return 0 for success, <0 on failure. */ POCKETSPHINX_EXPORT int ps_lattice_write_htk(ps_lattice_t *dag, char const *filename); /** * Get the log-math computation object for this lattice * * @return The log-math object for this lattice. The lattice retains * ownership of this pointer, so you should not attempt to * free it manually. Use logmath_retain() if you wish to * reuse it elsewhere. */ POCKETSPHINX_EXPORT logmath_t *ps_lattice_get_logmath(ps_lattice_t *dag); /** * Start iterating over nodes in the lattice. * * @note No particular order of traversal is guaranteed, and you * should not depend on this. * * @param dag Lattice to iterate over. * @return Iterator over lattice nodes. */ POCKETSPHINX_EXPORT ps_latnode_iter_t *ps_latnode_iter(ps_lattice_t *dag); /** * Move to next node in iteration. * @param itor Node iterator. * @return Updated node iterator, or NULL if finished */ POCKETSPHINX_EXPORT ps_latnode_iter_t *ps_latnode_iter_next(ps_latnode_iter_t *itor); /** * Stop iterating over nodes. * @param itor Node iterator. */ POCKETSPHINX_EXPORT void ps_latnode_iter_free(ps_latnode_iter_t *itor); /** * Get node from iterator. */ POCKETSPHINX_EXPORT ps_latnode_t *ps_latnode_iter_node(ps_latnode_iter_t *itor); /** * Get start and end time range for a node. * * @param node Node inquired about. * @param out_fef Output: End frame of first exit from this node. * @param out_lef Output: End frame of last exit from this node. * @return Start frame for all edges exiting this node. */ POCKETSPHINX_EXPORT int ps_latnode_times(ps_latnode_t *node, int16 *out_fef, int16 *out_lef); /** * Get word string for this node. * * @param dag Lattice to which node belongs. * @param node Node inquired about. * @return Word string for this node (possibly a pronunciation variant). */ POCKETSPHINX_EXPORT char const *ps_latnode_word(ps_lattice_t *dag, ps_latnode_t *node); /** * Get base word string for this node. * * @param dag Lattice to which node belongs. * @param node Node inquired about. * @return Base word string for this node. */ POCKETSPHINX_EXPORT char const *ps_latnode_baseword(ps_lattice_t *dag, ps_latnode_t *node); /** * Iterate over exits from this node. * * @param node Node inquired about. * @return Iterator over exit links from this node. */ POCKETSPHINX_EXPORT ps_latlink_iter_t *ps_latnode_exits(ps_latnode_t *node); /** * Iterate over entries to this node. * * @param node Node inquired about. * @return Iterator over entry links to this node. */ POCKETSPHINX_EXPORT ps_latlink_iter_t *ps_latnode_entries(ps_latnode_t *node); /** * Get best posterior probability and associated acoustic score from a lattice node. * * @param dag Lattice to which node belongs. * @param node Node inquired about. * @param out_link Output: exit link with highest posterior probability * @return Posterior probability of the best link exiting this node. * Log is expressed in the log-base used in the decoder. To * convert to linear floating-point, use * logmath_exp(ps_lattice_get_logmath(), pprob). */ POCKETSPHINX_EXPORT int32 ps_latnode_prob(ps_lattice_t *dag, ps_latnode_t *node, ps_latlink_t **out_link); /** * Get next link from a lattice link iterator. * * @param itor Iterator. * @return Updated iterator, or NULL if finished. */ POCKETSPHINX_EXPORT ps_latlink_iter_t *ps_latlink_iter_next(ps_latlink_iter_t *itor); /** * Stop iterating over links. * @param itor Link iterator. */ POCKETSPHINX_EXPORT void ps_latlink_iter_free(ps_latlink_iter_t *itor); /** * Get link from iterator. */ POCKETSPHINX_EXPORT ps_latlink_t *ps_latlink_iter_link(ps_latlink_iter_t *itor); /** * Get start and end times from a lattice link. * * @note these are inclusive - i.e. the last frame of * this word is ef, not ef-1. * * @param link Link inquired about. * @param out_sf Output: (optional) start frame of this link. * @return End frame of this link. */ POCKETSPHINX_EXPORT int ps_latlink_times(ps_latlink_t *link, int16 *out_sf); /** * Get destination and source nodes from a lattice link * * @param link Link inquired about * @param out_src Output: (optional) source node. * @return destination node */ POCKETSPHINX_EXPORT ps_latnode_t *ps_latlink_nodes(ps_latlink_t *link, ps_latnode_t **out_src); /** * Get word string from a lattice link. * * @param dag Lattice to which node belongs. * @param link Link inquired about * @return Word string for this link (possibly a pronunciation variant). */ POCKETSPHINX_EXPORT char const *ps_latlink_word(ps_lattice_t *dag, ps_latlink_t *link); /** * Get base word string from a lattice link. * * @param dag Lattice to which node belongs. * @param link Link inquired about * @return Base word string for this link */ POCKETSPHINX_EXPORT char const *ps_latlink_baseword(ps_lattice_t *dag, ps_latlink_t *link); /** * Get predecessor link in best path. * * @param link Link inquired about * @return Best previous link from bestpath search, if any. Otherwise NULL */ POCKETSPHINX_EXPORT ps_latlink_t *ps_latlink_pred(ps_latlink_t *link); /** * Get acoustic score and posterior probability from a lattice link. * * @param dag Lattice to which node belongs. * @param link Link inquired about * @param out_ascr Output: (optional) acoustic score. * @return Posterior probability for this link. Log is expressed in * the log-base used in the decoder. To convert to linear * floating-point, use logmath_exp(ps_lattice_get_logmath(), pprob). */ POCKETSPHINX_EXPORT int32 ps_latlink_prob(ps_lattice_t *dag, ps_latlink_t *link, int32 *out_ascr); /** * Create a directed link between "from" and "to" nodes, but if a link already exists, * choose one with the best link_scr. */ POCKETSPHINX_EXPORT void ps_lattice_link(ps_lattice_t *dag, ps_latnode_t *from, ps_latnode_t *to, int32 score, int32 ef); /** * Start a forward traversal of edges in a word graph. * * @note A keen eye will notice an inconsistency in this API versus * other types of iterators in PocketSphinx. The reason for this is * that the traversal algorithm is much more efficient when it is able * to modify the lattice structure. Therefore, to avoid giving the * impression that multiple traversals are possible at once, no * separate iterator structure is provided. * * @param dag Lattice to be traversed. * @param start Start node (source) of traversal. * @param end End node (goal) of traversal. * @return First link in traversal. */ POCKETSPHINX_EXPORT ps_latlink_t *ps_lattice_traverse_edges(ps_lattice_t *dag, ps_latnode_t *start, ps_latnode_t *end); /** * Get the next link in forward traversal. * * @param dag Lattice to be traversed. * @param end End node (goal) of traversal. * @return Next link in traversal. */ POCKETSPHINX_EXPORT ps_latlink_t *ps_lattice_traverse_next(ps_lattice_t *dag, ps_latnode_t *end); /** * Start a reverse traversal of edges in a word graph. * * @note See ps_lattice_traverse_edges() for why this API is the way it is. * * @param dag Lattice to be traversed. * @param start Start node (goal) of traversal. * @param end End node (source) of traversal. * @return First link in traversal. */ POCKETSPHINX_EXPORT ps_latlink_t *ps_lattice_reverse_edges(ps_lattice_t *dag, ps_latnode_t *start, ps_latnode_t *end); /** * Get the next link in reverse traversal. * * @param dag Lattice to be traversed. * @param start Start node (goal) of traversal. * @return Next link in traversal. */ POCKETSPHINX_EXPORT ps_latlink_t *ps_lattice_reverse_next(ps_lattice_t *dag, ps_latnode_t *start); /** * Do N-Gram based best-path search on a word graph. * * This function calculates both the best path as well as the forward * probability used in confidence estimation. * * @return Final link in best path, NULL on error. */ POCKETSPHINX_EXPORT ps_latlink_t *ps_lattice_bestpath(ps_lattice_t *dag, ngram_model_t *lmset, float32 lwf, float32 ascale); /** * Calculate link posterior probabilities on a word graph. * * This function assumes that bestpath search has already been done. * * @return Posterior probability of the utterance as a whole. */ POCKETSPHINX_EXPORT int32 ps_lattice_posterior(ps_lattice_t *dag, ngram_model_t *lmset, float32 ascale); /** * Prune all links (and associated nodes) below a certain posterior probability. * * This function assumes that ps_lattice_posterior() has already been called. * * @param beam Minimum posterior probability for links. This is * expressed in the log-base used in the decoder. To convert * from linear floating-point, use * logmath_log(ps_lattice_get_logmath(), prob). * @return number of arcs removed. */ POCKETSPHINX_EXPORT int32 ps_lattice_posterior_prune(ps_lattice_t *dag, int32 beam); #ifdef NOT_IMPLEMENTED_YET /** * Expand lattice using an N-gram language model. * * This function expands the lattice such that each node represents a * unique N-gram history, and adds language model scores to the links. */ POCKETSPHINX_EXPORT int32 ps_lattice_ngram_expand(ps_lattice_t *dag, ngram_model_t *lm); #endif /** * Get the number of frames in the lattice. * * @param dag The lattice in question. * @return Number of frames in this lattice. */ POCKETSPHINX_EXPORT int ps_lattice_n_frames(ps_lattice_t *dag); #endif /* __PS_LATTICE_H__ */