/*
* Compute the top-N closest gaussians from the chosen set (mgau,feat)
* for the given input observation vector.
*/
static int32
compute_dist(gauden_dist_t * out_dist, int32 n_top,
mfcc_t * obs, int32 featlen,
mfcc_t ** mean, mfcc_t ** var, mfcc_t * det,
int32 n_density)
{
int32 i, j, d;
gauden_dist_t *worst;
/* Special case optimization when n_density <= n_top */
if (n_top >= n_density)
return (compute_dist_all
(out_dist, obs, featlen, mean, var, det, n_density));
for (i = 0; i < n_top; i++)
out_dist[i].dist = WORST_DIST;
worst = &(out_dist[n_top - 1]);
for (d = 0; d < n_density; d++) {
mfcc_t *m;
mfcc_t *v;
mfcc_t dval;
m = mean[d];
v = var[d];
dval = det[d];
for (i = 0; (i < featlen) && (dval >= worst->dist); i++) {
mfcc_t diff;
#ifdef FIXED_POINT
/* Have to check for underflows here. */
mfcc_t pdval = dval;
diff = obs[i] - m[i];
dval -= MFCCMUL(MFCCMUL(diff, diff), v[i]);
if (dval > pdval) {
dval = WORST_SCORE;
break;
}
#else
diff = obs[i] - m[i];
/* The compiler really likes this to be a single
* expression, for whatever reason. */
dval -= diff * diff * v[i];
#endif
}
if ((i < featlen) || (dval < worst->dist)) /* Codeword d worse than worst */
continue;
/* Codeword d at least as good as worst so far; insert in the ordered list */
for (i = 0; (i < n_top) && (dval < out_dist[i].dist); i++);
assert(i < n_top);
for (j = n_top - 1; j > i; --j)
out_dist[j] = out_dist[j - 1];
out_dist[i].dist = dval;
out_dist[i].id = d;
}
return 0;
}
/*
* Compute the top-N closest gaussians from the chosen set (mgau,feat)
* for the given input observation vector.
* NOTE: The density values computed are in log-domain, and while they are being
* computed they're really the DENOMINATOR of the distance expression.
*/
static int32
compute_dist(dist_t * out_dist, int32 n_top,
vector_t obs, int32 featlen,
vector_t * mean, vector_t * var, float32 * det,
int32 n_density)
{
int32 i, j, d;
dist_t *worst;
vector_t m, v;
float64 dval, diff;
/* Special case optimization when n_density <= n_top */
if (n_top >= n_density)
return (compute_dist_all
(out_dist, obs, featlen, mean, var, det, n_density));
/*
* We are really computing denominators in the gaussian density expression:
* sqrt(2pi * det), and (x-mean)^2*var.
* To maximize the density value, we want to minimize the denominators.
*/
for (i = 0; i < n_top; i++)
out_dist[i].dist = DBL_MAX;
worst = &(out_dist[n_top - 1]);
for (d = 0; d < n_density; d++) {
m = mean[d];
v = var[d];
dval = det[d];
for (i = 0; (i < featlen) && (dval <= worst->dist); i++) {
diff = obs[i] - m[i];
dval += diff * diff * v[i];
}
if ((i < featlen) || (dval >= worst->dist)) /* Codeword d worse than worst */
continue;
/* Codeword d at least as good as worst so far; insert in the ordered list */
for (i = 0; (i < n_top) && (dval >= out_dist[i].dist); i++);
assert(i < n_top);
for (j = n_top - 1; j > i; --j)
out_dist[j] = out_dist[j - 1];
out_dist[i].dist = dval;
out_dist[i].id = d;
}
return 0;
}
