fsg_history.h
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/*
* fsg_history.h -- FSG Viterbi decode history
*
* **********************************************
* CMU ARPA Speech Project
*
* Copyright (c) 1999 Carnegie Mellon University.
* ALL RIGHTS RESERVED.
* **********************************************
*
* HISTORY
*
* $Log: fsg_history.h,v $
* Revision 1.1.1.1 2006/05/23 18:45:02 dhuggins
* re-importation
*
* Revision 1.1 2004/07/16 00:57:12 egouvea
* Added Ravi's implementation of FSG support.
*
* Revision 1.7 2004/07/07 22:30:35 rkm
* *** empty log message ***
*
* Revision 1.6 2004/07/07 13:56:33 rkm
* Added reporting of (acoustic score - best senone score)/frame
*
* Revision 1.5 2004/06/25 14:49:08 rkm
* Optimized size of history table and speed of word transitions by maintaining only best scoring word exits at each state
*
* Revision 1.4 2004/06/23 20:32:16 rkm
* *** empty log message ***
*
* Revision 1.3 2004/05/27 15:16:08 rkm
* *** empty log message ***
*
*
* 25-Feb-2004 M K Ravishankar (rkm@cs.cmu.edu) at Carnegie Mellon University
* Started, based on S3.3 version.
*/
#ifndef __S2_FSG_HISTORY_H__
#define __S2_FSG_HISTORY_H__
/* SphinxBase headers. */
#include <sphinxbase/prim_type.h>
#include <sphinxbase/fsg_model.h>
/* Local headers. */
#include "blkarray_list.h"
#include "fsg_lextree.h"
#include "dict.h"
/*
* The Viterbi history structure. This is a tree, with the root at the
* FSG start state, at frame 0, with a null predecessor.
*/
/*
* A single Viterbi history entry
*/
typedef struct fsg_hist_entry_s {
fsg_link_t *fsglink; /* Link taken result in this entry */
int32 score; /* Total path score at the end of this
transition */
int32 pred; /* Predecessor entry; -1 if none */
frame_idx_t frame; /* Ending frame for this entry */
int16 lc; /* Left context provided by this entry to
succeeding words */
fsg_pnode_ctxt_t rc; /* Possible right contexts to which this entry
applies */
} fsg_hist_entry_t;
/* Access macros */
#define fsg_hist_entry_fsglink(v) ((v)->fsglink)
#define fsg_hist_entry_frame(v) ((v)->frame)
#define fsg_hist_entry_score(v) ((v)->score)
#define fsg_hist_entry_pred(v) ((v)->pred)
#define fsg_hist_entry_lc(v) ((v)->lc)
#define fsg_hist_entry_rc(v) ((v)->rc)
/*
* The entire tree of history entries (fsg_history_t.entries).
* Optimization: In a given frame, there may be several history entries, with
* the same left and right phonetic context, terminating in a particular state.
* Only the best scoring one of these needs to be saved, since everything else
* will be pruned according to the Viterbi algorithm. frame_entries is used
* temporarily in each frame to determine these best scoring entries in that
* frame. Only the ones not pruned are transferred to entries at the end of
* the frame. However, null transitions are a problem since they create
* entries that depend on entries created in the CURRENT frame. Hence, this
* pruning is done in two stages: first for the non-null transitions, and then
* for the null transitions alone. (This solution is sub-optimal, and can be
* improved with a little more work. SMOP.)
* Why is frame_entries a list? Each entry has a unique terminating state,
* and has a unique lc CIphone. But it has a SET of rc CIphones.
* frame_entries[s][lc] is an ordered list of entries created in the current
* frame, terminating in state s, and with left context lc. The list is in
* descending order of path score. When a new entry with (s,lc) arrives,
* its position in the list is determined. Then its rc set is modified by
* subtracting the union of the rc's of all its predecessors (i.e., better
* scoring entries). If the resulting rc set is empty, the entry is discarded.
* Otherwise, it is inserted, and the rc sets of all downstream entries in the
* list are updated by subtracting the new entry's rc. If any of them becomes
* empty, it is also discarded.
* As mentioned earlier, this procedure is applied in two stages, for the
* non-null transitions, and the null transitions, separately.
*/
typedef struct fsg_history_s {
fsg_model_t *fsg; /* The FSG for which this object applies */
blkarray_list_t *entries; /* A list of history table entries; the root
entry is the first element of the list */
glist_t **frame_entries;
int n_ciphone;
} fsg_history_t;
/*
* One-time intialization: Allocate and return an initially empty history
* module.
*/
fsg_history_t *fsg_history_init(fsg_model_t *fsg, dict_t *dict);
void fsg_history_utt_start(fsg_history_t *h);
void fsg_history_utt_end(fsg_history_t *h);
/*
* Create a history entry recording the completion of the given FSG
* transition, at the end of the given frame, with the given score, and
* the given predecessor history entry.
* The entry is initially temporary, and may be superseded by another
* with a higher score. The surviving entries must be transferred to
* the main history table, via fsg_history_end_frame().
*/
void fsg_history_entry_add (fsg_history_t *h,
fsg_link_t *l, /* FSG transition */
int32 frame,
int32 score,
int32 pred,
int32 lc,
fsg_pnode_ctxt_t rc);
/*
* Transfer the surviving history entries for this frame into the permanent
* history table. This function can be called several times during a frame.
* Each time, the entries surviving so far are transferred, and the temporary
* lists cleared. This feature is used to handle the entries due to non-null
* transitions and null transitions separately.
*/
void fsg_history_end_frame (fsg_history_t *h);
/* Clear the hitory table */
void fsg_history_reset (fsg_history_t *h);
/* Return the number of valid entries in the given history table */
int32 fsg_history_n_entries (fsg_history_t *h);
/*
* Return a ptr to the history entry for the given ID; NULL if there is no
* such entry.
*/
fsg_hist_entry_t *fsg_history_entry_get(fsg_history_t *h, int32 id);
/*
* Switch the FSG associated with the given history module. Should be done
* when the history list is empty. If not empty, the list is cleared.
*/
void fsg_history_set_fsg (fsg_history_t *h, fsg_model_t *fsg, dict_t *dict);
/* Free the given Viterbi search history object */
void fsg_history_free (fsg_history_t *h);
/* Print the entire history */
void fsg_history_print(fsg_history_t *h, dict_t *dict);
#endif
fsg_pnode_ctxt_t
Definition: fsg_lextree.h:60
fsg_hist_entry_s
Definition: fsg_history.h:95
blkarray_list_s
Definition: blkarray_list.h:79
dict.h
Operations on dictionary.
fsg_history_s
Definition: fsg_history.h:143
dict_t
a structure for a dictionary.
Definition: dict.h:76
frame_idx_t
int32 frame_idx_t
Type for frame index values.
Definition: hmm.h:64