PocketSphinx  5prealpha
hmm.h File Reference

Implementation of HMM base structure. More...

#include <stdio.h>
#include <sphinxbase/fixpoint.h>
#include <sphinxbase/listelem_alloc.h>
#include "bin_mdef.h"

Go to the source code of this file.

Data Structures

struct  hmm_context_s
 
struct  hmm_s
 

Macros

#define MAX_N_FRAMES   MAX_INT32
 Maximum number of frames in index, should be in sync with above.
 
#define SENSCR_SHIFT   10
 Shift count for senone scores. More...
 
#define WORST_SCORE   ((int)0xE0000000)
 Large "bad" score. More...
 
#define TMAT_WORST_SCORE   (-255)
 Watch out, though! Transition matrix entries that are supposed to be "zero" don't actually get that small due to quantization.
 
#define BETTER_THAN   >
 Is one score better than another?
 
#define WORSE_THAN   <
 Is one score worse than another?
 
#define HMM_MAX_NSTATE   5
 Hard-coded limit on the number of emitting states.
 
#define hmm_context(h)   (h)->ctx
 Access macros. More...
 
#define hmm_is_mpx(h)   (h)->mpx
 
#define hmm_in_score(h)   (h)->score[0]
 
#define hmm_score(h, st)   (h)->score[st]
 
#define hmm_out_score(h)   (h)->out_score
 
#define hmm_in_history(h)   (h)->history[0]
 
#define hmm_history(h, st)   (h)->history[st]
 
#define hmm_out_history(h)   (h)->out_history
 
#define hmm_bestscore(h)   (h)->bestscore
 
#define hmm_frame(h)   (h)->frame
 
#define hmm_mpx_ssid(h, st)   (h)->senid[st]
 
#define hmm_nonmpx_ssid(h)   (h)->ssid
 
#define hmm_ssid(h, st)
 
#define hmm_mpx_senid(h, st)
 
#define hmm_nonmpx_senid(h, st)   ((h)->senid[st])
 
#define hmm_senid(h, st)
 
#define hmm_senscr(h, st)
 
#define hmm_tmatid(h)   (h)->tmatid
 
#define hmm_tprob(h, i, j)   (-(h)->ctx->tp[hmm_tmatid(h)][i][j])
 
#define hmm_n_emit_state(h)   ((h)->n_emit_state)
 
#define hmm_n_state(h)   ((h)->n_emit_state + 1)
 
#define hmm_context_set_senscore(ctx, senscr)   ((ctx)->senscore = (senscr))
 Change the senone score array for a context.
 

Typedefs

typedef int32 frame_idx_t
 Type for frame index values. More...
 
typedef struct hmm_context_s hmm_context_t
 
typedef struct hmm_s hmm_t
 

Functions

hmm_context_thmm_context_init (int32 n_emit_state, uint8 **const *tp, int16 const *senscore, uint16 *const *sseq)
 Create an HMM context.
 
void hmm_context_free (hmm_context_t *ctx)
 Free an HMM context. More...
 
void hmm_init (hmm_context_t *ctx, hmm_t *hmm, int mpx, int ssid, int tmatid)
 Populate a previously-allocated HMM structure, allocating internal data.
 
void hmm_deinit (hmm_t *hmm)
 Free an HMM structure, releasing internal data (but not the HMM structure itself).
 
void hmm_clear (hmm_t *h)
 Reset the states of the HMM to the invalid condition. More...
 
void hmm_clear_scores (hmm_t *h)
 Reset the scores of the HMM.
 
void hmm_normalize (hmm_t *h, int32 bestscr)
 Renormalize the scores in this HMM based on the given best score.
 
void hmm_enter (hmm_t *h, int32 score, int32 histid, int frame)
 Enter an HMM with the given path score and history ID.
 
int32 hmm_vit_eval (hmm_t *hmm)
 Viterbi evaluation of given HMM. More...
 
int32 hmm_dump_vit_eval (hmm_t *hmm, FILE *fp)
 Like hmm_vit_eval, but dump HMM state and relevant senscr to fp first, for debugging;. More...
 
void hmm_dump (hmm_t *h, FILE *fp)
 For debugging, dump the whole HMM out. More...
 

Detailed Description

Implementation of HMM base structure.

HMM data structure and operation.

Hidden Markov Model base structures.

For efficiency, this version is hardwired for two possible HMM topologies, but will fall back to others:

5-state left-to-right HMMs: (0 is the emitting entry state and E is a non-emitting exit state; the x's indicate allowed transitions between source and destination states):

              0   1   2   3   4   E (destination-states)
          0   x   x   x
          1       x   x   x
          2           x   x   x
          3               x   x   x
          4                   x   x
   (source-states)

5-state topologies that contain a subset of the above transitions should work as well.

3-state left-to-right HMMs (similar notation as the 5-state topology above):

              0   1   2   E (destination-states)
          0   x   x   x
          1       x   x   x
          2           x   x 
   (source-states)

3-state topologies that contain a subset of the above transitions should work as well.

Definition in file hmm.h.

Macro Definition Documentation

#define hmm_context (   h)    (h)->ctx

Access macros.

Definition at line 186 of file hmm.h.

#define hmm_mpx_senid (   h,
  st 
)
Value:
(hmm_mpx_ssid(h,st) == BAD_SENID \
? BAD_SENID : (h)->ctx->sseq[hmm_mpx_ssid(h,st)][st])
#define BAD_SENID
Invalid senone ID (limited to 16 bits for PocketSphinx).
Definition: bin_mdef.h:98

Definition at line 203 of file hmm.h.

#define hmm_senid (   h,
  st 
)
Value:
(hmm_is_mpx(h) \
? hmm_mpx_senid(h,st) : hmm_nonmpx_senid(h,st))

Definition at line 206 of file hmm.h.

#define hmm_senscr (   h,
  st 
)
Value:
(hmm_senid(h,st) == BAD_SENID \
: -(h)->ctx->senscore[hmm_senid(h,st)])
#define BAD_SENID
Invalid senone ID (limited to 16 bits for PocketSphinx).
Definition: bin_mdef.h:98
#define WORST_SCORE
Large &quot;bad&quot; score.
Definition: hmm.h:84

Definition at line 208 of file hmm.h.

#define hmm_ssid (   h,
  st 
)
Value:
(hmm_is_mpx(h) \
? hmm_mpx_ssid(h,st) : hmm_nonmpx_ssid(h))

Definition at line 201 of file hmm.h.

#define SENSCR_SHIFT   10
#define WORST_SCORE   ((int)0xE0000000)

Large "bad" score.

This number must be "bad" enough so that 4 times WORST_SCORE will not overflow. The reason for this is that the search doesn't check the scores in a model before evaluating the model and it may require as many was 4 plies before the new 'good' score can wipe out the initial WORST_SCORE initialization.

Definition at line 84 of file hmm.h.

Referenced by hmm_clear(), hmm_clear_scores(), hmm_normalize(), ngram_fwdflat_search(), ngram_search_find_exit(), ngram_search_lattice(), ngram_search_save_bp(), ps_astar_start(), ps_lattice_read(), ps_lattice_write(), and ps_lattice_write_htk().

Typedef Documentation

typedef int32 frame_idx_t

Type for frame index values.

Used in HMM indexes and backpointers and affects memory required.Due to limitations of FSG search implementation this value needs to be signed.

Definition at line 64 of file hmm.h.

Function Documentation

void hmm_clear ( hmm_t h)

Reset the states of the HMM to the invalid condition.

i.e., scores to WORST_SCORE and hist to undefined.

Definition at line 183 of file hmm.c.

References WORST_SCORE.

Referenced by fsg_psubtree_pnode_deactivate(), hmm_init(), ngram_fwdflat_start(), ngram_fwdtree_finish(), and ngram_fwdtree_start().

void hmm_context_free ( hmm_context_t ctx)

Free an HMM context.

Note
The transition matrices, senone scores, and senone sequence mapping are all assumed to be allocated externally, and will NOT be freed by this function.

Definition at line 80 of file hmm.c.

Referenced by ngram_search_free().

void hmm_dump ( hmm_t h,
FILE *  fp 
)

For debugging, dump the whole HMM out.

Parameters
hIn/Out: HMM being updated
fpAn output file pointer

Definition at line 116 of file hmm.c.

Referenced by hmm_dump_vit_eval().

int32 hmm_dump_vit_eval ( hmm_t hmm,
FILE *  fp 
)

Like hmm_vit_eval, but dump HMM state and relevant senscr to fp first, for debugging;.

Parameters
hmmIn/Out: HMM being updated
fpAn output file pointer

Definition at line 810 of file hmm.c.

References hmm_dump(), and hmm_vit_eval().

int32 hmm_vit_eval ( hmm_t hmm)

Viterbi evaluation of given HMM.

Note
If this module were being used for tracking state segmentations, the dummy, non-emitting exit state would have to be updated separately. In the Viterbi DP diagram, transitions to the exit state occur from the current time; they are vertical transitions. Hence they should be made only after the history has been logged for the emitting states. But we're not bothered with state segmentations, for now. So, we update the exit state as well.

Definition at line 789 of file hmm.c.

Referenced by hmm_dump_vit_eval().