tenfourfox/media/pocketsphinx/ps_lattice.h

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2017-04-19 07:56:45 +00:00
/* -*- 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 <sphinxbase/prim_type.h>
#include <sphinxbase/ngram_model.h>
/* PocketSphinx headers. */
#include <pocketsphinx_export.h>
/**
* 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 <strong>inclusive</strong> - 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__ */