PocketSphinx  5prealpha
ps_lattice.h File Reference

Word graph search. More...

#include <sphinxbase/prim_type.h>
#include <sphinxbase/ngram_model.h>
#include <pocketsphinx_export.h>

Go to the source code of this file.

Typedefs

typedef struct ps_lattice_s ps_lattice_t
 Word graph structure used in bestpath/nbest search.
 
typedef struct ps_latnode_s ps_latnode_t
 DAG nodes. More...
 
typedef struct ps_latnode_s ps_latnode_iter_t
 Iterator over DAG nodes.
 
typedef struct ps_latlink_s ps_latlink_t
 Links between DAG nodes. More...
 
typedef struct latlink_list_s ps_latlink_iter_t
 Iterator over DAG links.
 

Functions

POCKETSPHINX_EXPORT ps_lattice_tps_lattice_read (struct ps_decoder_s *ps, char const *file)
 Read a lattice from a file on disk. More...
 
POCKETSPHINX_EXPORT ps_lattice_tps_lattice_retain (ps_lattice_t *dag)
 Retain a lattice. More...
 
POCKETSPHINX_EXPORT int ps_lattice_free (ps_lattice_t *dag)
 Free a lattice. More...
 
POCKETSPHINX_EXPORT int ps_lattice_write (ps_lattice_t *dag, char const *filename)
 Write a lattice to disk. More...
 
POCKETSPHINX_EXPORT int ps_lattice_write_htk (ps_lattice_t *dag, char const *filename)
 Write a lattice to disk in HTK format. More...
 
POCKETSPHINX_EXPORT logmath_t * ps_lattice_get_logmath (ps_lattice_t *dag)
 Get the log-math computation object for this lattice. More...
 
POCKETSPHINX_EXPORT
ps_latnode_iter_t
ps_latnode_iter (ps_lattice_t *dag)
 Start iterating over nodes in the lattice. More...
 
POCKETSPHINX_EXPORT
ps_latnode_iter_t
ps_latnode_iter_next (ps_latnode_iter_t *itor)
 Move to next node in iteration. More...
 
POCKETSPHINX_EXPORT void ps_latnode_iter_free (ps_latnode_iter_t *itor)
 Stop iterating over nodes. More...
 
POCKETSPHINX_EXPORT ps_latnode_tps_latnode_iter_node (ps_latnode_iter_t *itor)
 Get node from iterator.
 
POCKETSPHINX_EXPORT int ps_latnode_times (ps_latnode_t *node, int16 *out_fef, int16 *out_lef)
 Get start and end time range for a node. More...
 
POCKETSPHINX_EXPORT char const * ps_latnode_word (ps_lattice_t *dag, ps_latnode_t *node)
 Get word string for this node. More...
 
POCKETSPHINX_EXPORT char const * ps_latnode_baseword (ps_lattice_t *dag, ps_latnode_t *node)
 Get base word string for this node. More...
 
POCKETSPHINX_EXPORT
ps_latlink_iter_t
ps_latnode_exits (ps_latnode_t *node)
 Iterate over exits from this node. More...
 
POCKETSPHINX_EXPORT
ps_latlink_iter_t
ps_latnode_entries (ps_latnode_t *node)
 Iterate over entries to this node. More...
 
POCKETSPHINX_EXPORT int32 ps_latnode_prob (ps_lattice_t *dag, ps_latnode_t *node, ps_latlink_t **out_link)
 Get best posterior probability and associated acoustic score from a lattice node. More...
 
POCKETSPHINX_EXPORT
ps_latlink_iter_t
ps_latlink_iter_next (ps_latlink_iter_t *itor)
 Get next link from a lattice link iterator. More...
 
POCKETSPHINX_EXPORT void ps_latlink_iter_free (ps_latlink_iter_t *itor)
 Stop iterating over links. More...
 
POCKETSPHINX_EXPORT ps_latlink_tps_latlink_iter_link (ps_latlink_iter_t *itor)
 Get link from iterator.
 
POCKETSPHINX_EXPORT int ps_latlink_times (ps_latlink_t *link, int16 *out_sf)
 Get start and end times from a lattice link. More...
 
POCKETSPHINX_EXPORT ps_latnode_tps_latlink_nodes (ps_latlink_t *link, ps_latnode_t **out_src)
 Get destination and source nodes from a lattice link. More...
 
POCKETSPHINX_EXPORT char const * ps_latlink_word (ps_lattice_t *dag, ps_latlink_t *link)
 Get word string from a lattice link. More...
 
POCKETSPHINX_EXPORT char const * ps_latlink_baseword (ps_lattice_t *dag, ps_latlink_t *link)
 Get base word string from a lattice link. More...
 
POCKETSPHINX_EXPORT ps_latlink_tps_latlink_pred (ps_latlink_t *link)
 Get predecessor link in best path. More...
 
POCKETSPHINX_EXPORT int32 ps_latlink_prob (ps_lattice_t *dag, ps_latlink_t *link, int32 *out_ascr)
 Get acoustic score and posterior probability from a lattice link. More...
 
POCKETSPHINX_EXPORT void ps_lattice_link (ps_lattice_t *dag, ps_latnode_t *from, ps_latnode_t *to, int32 score, int32 ef)
 Create a directed link between "from" and "to" nodes, but if a link already exists, choose one with the best link_scr.
 
POCKETSPHINX_EXPORT ps_latlink_tps_lattice_traverse_edges (ps_lattice_t *dag, ps_latnode_t *start, ps_latnode_t *end)
 Start a forward traversal of edges in a word graph. More...
 
POCKETSPHINX_EXPORT ps_latlink_tps_lattice_traverse_next (ps_lattice_t *dag, ps_latnode_t *end)
 Get the next link in forward traversal. More...
 
POCKETSPHINX_EXPORT ps_latlink_tps_lattice_reverse_edges (ps_lattice_t *dag, ps_latnode_t *start, ps_latnode_t *end)
 Start a reverse traversal of edges in a word graph. More...
 
POCKETSPHINX_EXPORT ps_latlink_tps_lattice_reverse_next (ps_lattice_t *dag, ps_latnode_t *start)
 Get the next link in reverse traversal. More...
 
POCKETSPHINX_EXPORT ps_latlink_tps_lattice_bestpath (ps_lattice_t *dag, ngram_model_t *lmset, float32 lwf, float32 ascale)
 Do N-Gram based best-path search on a word graph. More...
 
POCKETSPHINX_EXPORT int32 ps_lattice_posterior (ps_lattice_t *dag, ngram_model_t *lmset, float32 ascale)
 Calculate link posterior probabilities on a word graph. More...
 
POCKETSPHINX_EXPORT int32 ps_lattice_posterior_prune (ps_lattice_t *dag, int32 beam)
 Prune all links (and associated nodes) below a certain posterior probability. More...
 
POCKETSPHINX_EXPORT int ps_lattice_n_frames (ps_lattice_t *dag)
 Get the number of frames in the lattice. More...
 

Detailed Description

Word graph search.

Definition in file ps_lattice.h.

Typedef Documentation

typedef struct ps_latlink_s ps_latlink_t

Links between DAG nodes.

A link corresponds to a single hypothesized instance of a word with a given start and end point.

Definition at line 83 of file ps_lattice.h.

typedef struct ps_latnode_s ps_latnode_t

DAG nodes.

A node corresponds to a number of hypothesized instances of a word which all share the same starting point.

Definition at line 70 of file ps_lattice.h.

Function Documentation

POCKETSPHINX_EXPORT char const* ps_latlink_baseword ( ps_lattice_t dag,
ps_latlink_t link 
)

Get base word string from a lattice link.

Parameters
dagLattice to which node belongs.
linkLink inquired about
Returns
Base word string for this link

Definition at line 808 of file ps_lattice.c.

References ps_latnode_s::basewid, ps_lattice_s::dict, and ps_latlink_s::from.

POCKETSPHINX_EXPORT void ps_latlink_iter_free ( ps_latlink_iter_t itor)

Stop iterating over links.

Parameters
itorLink iterator.

Definition at line 767 of file ps_lattice.c.

POCKETSPHINX_EXPORT ps_latlink_iter_t* ps_latlink_iter_next ( ps_latlink_iter_t itor)

Get next link from a lattice link iterator.

Parameters
itorIterator.
Returns
Updated iterator, or NULL if finished.

Definition at line 761 of file ps_lattice.c.

POCKETSPHINX_EXPORT ps_latnode_t* ps_latlink_nodes ( ps_latlink_t link,
ps_latnode_t **  out_src 
)

Get destination and source nodes from a lattice link.

Parameters
linkLink inquired about
out_srcOutput: (optional) source node.
Returns
destination node

Definition at line 793 of file ps_lattice.c.

References ps_latlink_s::from, and ps_latlink_s::to.

POCKETSPHINX_EXPORT ps_latlink_t* ps_latlink_pred ( ps_latlink_t link)

Get predecessor link in best path.

Parameters
linkLink inquired about
Returns
Best previous link from bestpath search, if any. Otherwise NULL

Definition at line 816 of file ps_lattice.c.

POCKETSPHINX_EXPORT int32 ps_latlink_prob ( ps_lattice_t dag,
ps_latlink_t link,
int32 *  out_ascr 
)

Get acoustic score and posterior probability from a lattice link.

Parameters
dagLattice to which node belongs.
linkLink inquired about
out_ascrOutput: (optional) acoustic score.
Returns
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).

Definition at line 822 of file ps_lattice.c.

References ps_latlink_s::alpha, ps_latlink_s::ascr, ps_latlink_s::beta, ps_lattice_s::norm, and SENSCR_SHIFT.

POCKETSPHINX_EXPORT int ps_latlink_times ( ps_latlink_t link,
int16 *  out_sf 
)

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.
Parameters
linkLink inquired about.
out_sfOutput: (optional) start frame of this link.
Returns
End frame of this link.

Definition at line 779 of file ps_lattice.c.

References ps_latlink_s::ef, ps_latlink_s::from, and ps_latnode_s::sf.

POCKETSPHINX_EXPORT char const* ps_latlink_word ( ps_lattice_t dag,
ps_latlink_t link 
)

Get word string from a lattice link.

Parameters
dagLattice to which node belongs.
linkLink inquired about
Returns
Word string for this link (possibly a pronunciation variant).

Definition at line 800 of file ps_lattice.c.

References ps_lattice_s::dict, ps_latlink_s::from, and ps_latnode_s::wid.

POCKETSPHINX_EXPORT char const* ps_latnode_baseword ( ps_lattice_t dag,
ps_latnode_t node 
)

Get base word string for this node.

Parameters
dagLattice to which node belongs.
nodeNode inquired about.
Returns
Base word string for this node.

Definition at line 726 of file ps_lattice.c.

References ps_latnode_s::basewid, and ps_lattice_s::dict.

POCKETSPHINX_EXPORT ps_latlink_iter_t* ps_latnode_entries ( ps_latnode_t node)

Iterate over entries to this node.

Parameters
nodeNode inquired about.
Returns
Iterator over entry links to this node.

Definition at line 755 of file ps_lattice.c.

References ps_latnode_s::entries.

POCKETSPHINX_EXPORT ps_latlink_iter_t* ps_latnode_exits ( ps_latnode_t node)

Iterate over exits from this node.

Parameters
nodeNode inquired about.
Returns
Iterator over exit links from this node.

Definition at line 749 of file ps_lattice.c.

References ps_latnode_s::exits.

POCKETSPHINX_EXPORT ps_latnode_iter_t* ps_latnode_iter ( 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.
Parameters
dagLattice to iterate over.
Returns
Iterator over lattice nodes.

Definition at line 688 of file ps_lattice.c.

References ps_lattice_s::nodes.

POCKETSPHINX_EXPORT void ps_latnode_iter_free ( ps_latnode_iter_t itor)

Stop iterating over nodes.

Parameters
itorNode iterator.

Definition at line 700 of file ps_lattice.c.

POCKETSPHINX_EXPORT ps_latnode_iter_t* ps_latnode_iter_next ( ps_latnode_iter_t itor)

Move to next node in iteration.

Parameters
itorNode iterator.
Returns
Updated node iterator, or NULL if finished

Definition at line 694 of file ps_lattice.c.

References ps_latnode_s::next.

POCKETSPHINX_EXPORT int32 ps_latnode_prob ( ps_lattice_t dag,
ps_latnode_t node,
ps_latlink_t **  out_link 
)

Get best posterior probability and associated acoustic score from a lattice node.

Parameters
dagLattice to which node belongs.
nodeNode inquired about.
out_linkOutput: exit link with highest posterior probability
Returns
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).

Definition at line 732 of file ps_lattice.c.

References ps_latlink_s::alpha, ps_latlink_s::beta, ps_latnode_s::exits, ps_lattice_s::lmath, and ps_lattice_s::norm.

POCKETSPHINX_EXPORT int ps_latnode_times ( ps_latnode_t node,
int16 *  out_fef,
int16 *  out_lef 
)

Get start and end time range for a node.

Parameters
nodeNode inquired about.
out_fefOutput: End frame of first exit from this node.
out_lefOutput: End frame of last exit from this node.
Returns
Start frame for all edges exiting this node.

Definition at line 712 of file ps_lattice.c.

References ps_latnode_s::fef, ps_latnode_s::lef, and ps_latnode_s::sf.

POCKETSPHINX_EXPORT char const* ps_latnode_word ( ps_lattice_t dag,
ps_latnode_t node 
)

Get word string for this node.

Parameters
dagLattice to which node belongs.
nodeNode inquired about.
Returns
Word string for this node (possibly a pronunciation variant).

Definition at line 720 of file ps_lattice.c.

References ps_lattice_s::dict, and ps_latnode_s::wid.

POCKETSPHINX_EXPORT ps_latlink_t* ps_lattice_bestpath ( ps_lattice_t dag,
ngram_model_t *  lmset,
float32  lwf,
float32  ascale 
)
POCKETSPHINX_EXPORT int ps_lattice_free ( ps_lattice_t dag)
POCKETSPHINX_EXPORT logmath_t* ps_lattice_get_logmath ( ps_lattice_t dag)

Get the log-math computation object for this lattice.

Returns
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.

Definition at line 682 of file ps_lattice.c.

References ps_lattice_s::lmath.

POCKETSPHINX_EXPORT int ps_lattice_n_frames ( ps_lattice_t dag)

Get the number of frames in the lattice.

Parameters
dagThe lattice in question.
Returns
Number of frames in this lattice.

Definition at line 633 of file ps_lattice.c.

References ps_lattice_s::n_frames.

POCKETSPHINX_EXPORT int32 ps_lattice_posterior ( ps_lattice_t dag,
ngram_model_t *  lmset,
float32  ascale 
)

Calculate link posterior probabilities on a word graph.

This function assumes that bestpath search has already been done.

Returns
Posterior probability of the utterance as a whole.

Definition at line 1446 of file ps_lattice.c.

References ps_latlink_s::ascr, ps_latnode_s::basewid, ps_latlink_s::beta, BETTER_THAN, ps_lattice_s::dict, dict_filler_word(), ps_lattice_s::end, ps_latnode_s::exits, ps_lattice_s::final_node_ascr, ps_latlink_s::from, ps_lattice_s::lmath, ps_latnode_s::next, ps_lattice_s::nodes, ps_lattice_s::norm, ps_latlink_s::path_scr, ps_lattice_reverse_edges(), ps_lattice_reverse_next(), SENSCR_SHIFT, ps_lattice_s::start, and ps_latlink_s::to.

POCKETSPHINX_EXPORT int32 ps_lattice_posterior_prune ( ps_lattice_t dag,
int32  beam 
)

Prune all links (and associated nodes) below a certain posterior probability.

This function assumes that ps_lattice_posterior() has already been called.

Parameters
beamMinimum 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).
Returns
number of arcs removed.

Definition at line 1524 of file ps_lattice.c.

References ps_latlink_s::alpha, ps_latlink_s::beta, ps_lattice_s::end, ps_latnode_s::entries, ps_latnode_s::exits, ps_latlink_s::from, ps_lattice_s::latlink_alloc, ps_lattice_s::latlink_list_alloc, ps_lattice_s::norm, ps_lattice_delete_unreachable(), ps_lattice_traverse_edges(), ps_lattice_traverse_next(), ps_latnode_s::reachable, ps_lattice_s::start, and ps_latlink_s::to.

POCKETSPHINX_EXPORT ps_lattice_t* ps_lattice_retain ( ps_lattice_t dag)

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.

Returns
pointer to the retained lattice.

Definition at line 658 of file ps_lattice.c.

References ps_lattice_s::refcount.

POCKETSPHINX_EXPORT ps_latlink_t* ps_lattice_reverse_edges ( ps_lattice_t dag,
ps_latnode_t start,
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.
Parameters
dagLattice to be traversed.
startStart node (goal) of traversal.
endEnd node (source) of traversal.
Returns
First link in traversal.

Definition at line 1148 of file ps_lattice.c.

References ps_lattice_s::end, ps_latnode_s::entries, ps_latnode_s::exits, ps_latnode_s::fanin, ps_latnode_s::next, ps_lattice_s::nodes, ps_lattice_delq(), ps_lattice_pushq(), and ps_lattice_reverse_next().

Referenced by ps_lattice_posterior().

POCKETSPHINX_EXPORT ps_latlink_t* ps_lattice_reverse_next ( ps_lattice_t dag,
ps_latnode_t start 
)

Get the next link in reverse traversal.

Parameters
dagLattice to be traversed.
startStart node (goal) of traversal.
Returns
Next link in traversal.

Definition at line 1173 of file ps_lattice.c.

References ps_latnode_s::entries, ps_latnode_s::fanin, ps_latlink_s::from, ps_lattice_delq(), ps_lattice_popq(), ps_lattice_pushq(), and ps_lattice_s::start.

Referenced by ps_lattice_posterior(), and ps_lattice_reverse_edges().

POCKETSPHINX_EXPORT ps_latlink_t* ps_lattice_traverse_edges ( ps_lattice_t dag,
ps_latnode_t start,
ps_latnode_t end 
)

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.
Parameters
dagLattice to be traversed.
startStart node (source) of traversal.
endEnd node (goal) of traversal.
Returns
First link in traversal.

Definition at line 1091 of file ps_lattice.c.

References ps_latnode_s::exits, ps_latnode_s::fanin, ps_latnode_s::next, ps_lattice_s::nodes, ps_lattice_delq(), ps_lattice_pushq(), ps_lattice_traverse_next(), ps_lattice_s::start, and ps_latlink_s::to.

Referenced by ps_lattice_bestpath(), and ps_lattice_posterior_prune().

POCKETSPHINX_EXPORT ps_latlink_t* ps_lattice_traverse_next ( ps_lattice_t dag,
ps_latnode_t end 
)

Get the next link in forward traversal.

Parameters
dagLattice to be traversed.
endEnd node (goal) of traversal.
Returns
Next link in traversal.

Definition at line 1117 of file ps_lattice.c.

References ps_lattice_s::end, ps_latnode_s::exits, ps_latnode_s::fanin, ps_lattice_delq(), ps_lattice_popq(), ps_lattice_pushq(), and ps_latlink_s::to.

Referenced by ps_lattice_bestpath(), ps_lattice_posterior_prune(), and ps_lattice_traverse_edges().