/* HTS_b2en: calculate frame energy */
static double HTS_b2en(HTS_Vocoder * v, const double *b, const int m, const double a)
{
int i;
double en = 0.0;
double *cep;
double *ir;
if (v->spectrum2en_size < m) {
if (v->spectrum2en_buff != NULL)
HTS_free(v->spectrum2en_buff);
v->spectrum2en_buff = (double *) HTS_calloc((m + 1) + 2 * IRLENG, sizeof(double));
v->spectrum2en_size = m;
}
cep = v->spectrum2en_buff + m + 1;
ir = cep + IRLENG;
HTS_b2mc(b, v->spectrum2en_buff, m, a);
HTS_freqt(v, v->spectrum2en_buff, m, cep, IRLENG - 1, -a);
HTS_c2ir(cep, IRLENG, ir, IRLENG);
for (i = 0; i < IRLENG; i++)
en += ir[i] * ir[i];
return (en);
}
/* HTS_Vocoder_postfilter_mcp: postfilter for MCP */
void HTS_Vocoder_postfilter_mcp(HTS_Vocoder *v, double *mcp, const int m,
double alpha, double beta)
{
double e1, e2;
int k;
if (beta > 0.0 && m > 1) {
if (v->postfilter_size < m) {
if (v->postfilter_buff != NULL)
HTS_free(v->postfilter_buff);
v->postfilter_buff = (double *) HTS_calloc(m + 1, sizeof(double));
v->postfilter_size = m;
}
HTS_mc2b(mcp, v->postfilter_buff, m, alpha);
e1 = HTS_b2en(v, v->postfilter_buff, m, alpha);
v->postfilter_buff[1] -= beta * alpha * mcp[2];
for (k = 2; k <= m; k++)
v->postfilter_buff[k] *= (1.0 + beta);
e2 = HTS_b2en(v, v->postfilter_buff, m, alpha);
v->postfilter_buff[0] += log(e1 / e2) / 2;
HTS_b2mc(v->postfilter_buff, mcp, m, alpha);
}
}
