/**
* @brief Compute a set of Gaussians with safe pruning.
*
* If the N-best mixtures in the previous frame is specified in @a last_id,
* They are first computed to set the initial threshold.
* After that, the rest of the Gaussians will be computed with the thresholds
* to drop unpromising Gaussians from computation at early stage
* of likelihood computation. If the computation of a Gaussian reached to
* the end, the threshold will be updated to always hold the likelihood of
* current N-best score.
*
* The calculated scores will be stored to OP_calced_score, with its
* corresponding mixture id to OP_calced_id. These are done by calling
* cache_push().
* The number of calculated mixtures is also stored in OP_calced_num.
*
* This can be called from calc_tied_mix() or calc_mix().
*
* @param wrk [i/o] HMM computation work area
* @param g [in] set of Gaussian densities to compute the output probability
* @param gnum [in] length of above
* @param last_id [in] ID list of N-best mixture in previous input frame,
* or NULL if not exist
* @param lnum [in] length of last_id
*/
void
gprune_safe(HMMWork *wrk, HTK_HMM_Dens **g, int gnum, int *last_id, int lnum)
{
int i, j, num = 0;
LOGPROB score, thres;
if (last_id != NULL) { /* compute them first to form threshold */
/* 1. calculate first $OP_gprune_num and set initial threshold */
for (j=0; j<lnum; j++) {
i = last_id[j];
score = compute_g_base(wrk, g[i]);
num = cache_push(wrk, i, score, num);
wrk->mixcalced[i] = TRUE; /* mark them as calculated */
}
thres = wrk->OP_calced_score[num-1];
/* 2. calculate the rest with pruning*/
for (i = 0; i < gnum; i++) {
/* skip calced ones in 1. */
if (wrk->mixcalced[i]) {
wrk->mixcalced[i] = FALSE;
continue;
}
/* compute with safe pruning */
score = compute_g_safe(wrk, g[i], thres);
if (score <= thres) continue;
num = cache_push(wrk, i, score, num);
thres = wrk->OP_calced_score[num-1];
}
} else { /* in case the last_id not available */
/* not tied-mixture, or at the first 0 frame */
thres = LOG_ZERO;
for (i = 0; i < gnum; i++) {
if (num < wrk->OP_gprune_num) {
score = compute_g_base(wrk, g[i]);
} else {
score = compute_g_safe(wrk, g[i], thres);
if (score <= thres) continue;
}
num = cache_push(wrk, i, score, num);
thres = wrk->OP_calced_score[num-1];
}
}
wrk->OP_calced_num = num;
}
/**
* @brief Compute a set of Gaussians with heuristic pruning.
*
* If the N-best mixtures in the previous frame is specified in @a last_id,
* They are first computed to get the maximum value for each dimension.
* After that, the rest of the Gaussians will be computed using the maximum
* values as heuristics of uncomputed dimensions to drop unpromising
* Gaussians from computation at early stage
* of likelihood computation. If the @a last_id is not specified (typically
* at the first frame of the input), a safe pruning as same as one in
* gprune_safe.c will be applied.
*
* The calculated scores will be stored to OP_calced_score, with its
* corresponding mixture id to OP_calced_id. These are done by calling
* cache_push().
* The number of calculated mixtures is also stored in OP_calced_num.
*
* This can be called from calc_tied_mix() or calc_mix().
*
* @param wrk [i/o] HMM computation work area
* @param g [in] set of Gaussian densities to compute the output probability
* @param gnum [in] length of above
* @param last_id [in] ID list of N-best mixture in previous input frame,
* or NULL if not exist
* @param lnum [in] length of last_id
*/
void
gprune_heu(HMMWork *wrk, HTK_HMM_Dens **g, int gnum, int *last_id, int lnum)
{
int i, j, num = 0;
LOGPROB score, thres;
if (last_id != NULL) { /* compute them first to form thresholds */
/* 1. clear backmax */
init_backmax(wrk);
/* 2. calculate first $OP_gprune_num with setting max for each dimension */
for (j=0; j<lnum; j++) {
i = last_id[j];
score = compute_g_heu_updating(wrk, g[i]);
num = cache_push(wrk, i, score, num);
wrk->mixcalced[i] = TRUE; /* mark them as calculated */
}
/* 3. set backmax for each dimension */
make_backmax(wrk);
/* 4. calculate the rest with pruning*/
thres = wrk->OP_calced_score[num-1];
for (i = 0; i < gnum; i++) {
/* skip calced ones in 1. */
if (wrk->mixcalced[i]) {
wrk->mixcalced[i] = FALSE;
continue;
}
/* compute with safe pruning */
score = compute_g_heu_pruning(wrk, g[i], thres);
if (score > LOG_ZERO) {
num = cache_push(wrk, i, score, num);
thres = wrk->OP_calced_score[num-1];
}
}
} else { /* in case the last_id not available */
/* at the first 0 frame */
/* calculate with safe pruning */
thres = LOG_ZERO;
for (i = 0; i < gnum; i++) {
if (num < wrk->OP_gprune_num) {
score = compute_g_base(wrk, g[i]);
} else {
score = compute_g_safe(wrk, g[i], thres);
if (score <= thres) continue;
}
num = cache_push(wrk, i, score, num);
thres = wrk->OP_calced_score[num-1];
}
}
wrk->OP_calced_num = num;
}
/**
* @brief Compute a set of Gaussians with beam pruning.
*
* If the N-best mixtures in the previous frame is specified in @a last_id,
* They are first computed to set the thresholds for each dimension.
* After that, the rest of the Gaussians will be computed with those dimension
* thresholds to drop unpromising Gaussians from computation at early stage
* of likelihood computation. If the @a last_id is not specified (typically
* at the first frame of the input), a safe pruning as same as one in
* gprune_safe.c will be applied.
*
* The calculated scores will be stored to OP_calced_score, with its
* corresponding mixture id to OP_calced_id. These are done by calling
* cache_push().
* The number of calculated mixtures is also stored in OP_calced_num.
*
* This can be called from calc_tied_mix() or calc_mix().
*
* @param wrk [i/o] HMM computation work area
* @param g [in] set of Gaussian densities to compute the output probability
* @param gnum [in] length of above
* @param last_id [in] ID list of N-best mixture in previous input frame,
* or NULL if not exist
* @param lnum [in] length of last_id
*/
void
gprune_beam(HMMWork *wrk, HTK_HMM_Dens **g, int gnum, int *last_id, int lnum)
{
int i, j, num = 0;
LOGPROB score, thres;
if (last_id != NULL) { /* compute them first to form thresholds */
/* 1. clear dimthres */
clear_dimthres(wrk);
/* 2. calculate first $OP_gprune_num and set initial thresholds */
for (j=0; j<lnum; j++) {
i = last_id[j];
#ifdef TEST2
if (!g[i]) {
score = LOG_ZERO;
} else {
score = compute_g_beam_updating(wrk, g[i]);
}
num = cache_push(wrk, i, score, num);
#else
score = compute_g_beam_updating(wrk, g[i]);
num = cache_push(wrk, i, score, num);
#endif
wrk->mixcalced[i] = TRUE; /* mark them as calculated */
}
/* 3. set pruning thresholds for each dimension */
set_dimthres(wrk);
/* 4. calculate the rest with pruning*/
for (i = 0; i < gnum; i++) {
/* skip calced ones in 1. */
if (wrk->mixcalced[i]) {
wrk->mixcalced[i] = FALSE;
continue;
}
#ifdef TEST2
/* compute with safe pruning */
if (!g[i]) continue;
score = compute_g_beam_pruning(wrk, g[i]);
if (score > LOG_ZERO) {
num = cache_push(wrk, i, score, num);
}
#else
/* compute with safe pruning */
score = compute_g_beam_pruning(wrk, g[i]);
if (score > LOG_ZERO) {
num = cache_push(wrk, i, score, num);
}
#endif
}
} else { /* in case the last_id not available */
/* at the first 0 frame */
/* calculate with safe pruning */
thres = LOG_ZERO;
for (i = 0; i < gnum; i++) {
if (num < wrk->OP_gprune_num) {
score = compute_g_base(wrk, g[i]);
} else {
score = compute_g_safe(wrk, g[i], thres);
if (score <= thres) continue;
}
num = cache_push(wrk, i, score, num);
thres = wrk->OP_calced_score[num-1];
}
}
wrk->OP_calced_num = num;
}