/* Transform a masking curve (power spectrum) into a pole-zero filter */
void curve_to_lpc(VorbisPsy *psy, float *curve, float *awk1, float *awk2, int ord)
{
int i;
float ac[psy->n];
float tmp;
int len = psy->n >> 1;
for (i=0;i<2*len;i++)
ac[i] = 0;
for (i=1;i<len;i++)
ac[2*i-1] = curve[i];
ac[0] = curve[0];
ac[2*len-1] = curve[len-1];
spx_drft_backward(&psy->lookup, ac);
_spx_lpc(awk1, ac, ord);
tmp = 1.;
for (i=0;i<ord;i++)
{
tmp *= .99;
awk1[i] *= tmp;
}
#if 0
for (i=0;i<ord;i++)
awk2[i] = 0;
#else
/* Use the second (awk2) filter to correct the first one */
for (i=0;i<2*len;i++)
ac[i] = 0;
for (i=0;i<ord;i++)
ac[i+1] = awk1[i];
ac[0] = 1;
spx_drft_forward(&psy->lookup, ac);
/* Compute (power) response of awk1 (all zero) */
ac[0] *= ac[0];
for (i=1;i<len;i++)
ac[i] = ac[2*i-1]*ac[2*i-1] + ac[2*i]*ac[2*i];
ac[len] = ac[2*len-1]*ac[2*len-1];
/* Compute correction required */
for (i=0;i<len;i++)
curve[i] = 1. / (1e-6f+curve[i]*ac[i]);
for (i=0;i<2*len;i++)
ac[i] = 0;
for (i=1;i<len;i++)
ac[2*i-1] = curve[i];
ac[0] = curve[0];
ac[2*len-1] = curve[len-1];
spx_drft_backward(&psy->lookup, ac);
_spx_lpc(awk2, ac, ord);
tmp = 1;
for (i=0;i<ord;i++)
{
tmp *= .99;
awk2[i] *= tmp;
}
#endif
}
int sb_encode(void *state, void *vin, SpeexBits *bits)
{
SBEncState *st;
int i, roots, sub;
char *stack;
VARDECL(spx_mem_t *mem);
VARDECL(spx_sig_t *innov);
VARDECL(spx_word16_t *target);
VARDECL(spx_word16_t *syn_resp);
VARDECL(spx_word32_t *low_pi_gain);
spx_word16_t *low;
spx_word16_t *high;
VARDECL(spx_word16_t *low_exc_rms);
VARDECL(spx_word16_t *low_innov_rms);
const SpeexSBMode *mode;
spx_int32_t dtx;
spx_word16_t *in = (spx_word16_t*)vin;
spx_word16_t e_low=0, e_high=0;
VARDECL(spx_coef_t *lpc);
VARDECL(spx_coef_t *interp_lpc);
VARDECL(spx_coef_t *bw_lpc1);
VARDECL(spx_coef_t *bw_lpc2);
VARDECL(spx_lsp_t *lsp);
VARDECL(spx_lsp_t *qlsp);
VARDECL(spx_lsp_t *interp_lsp);
VARDECL(spx_lsp_t *interp_qlsp);
st = (SBEncState*)state;
stack=st->stack;
mode = (const SpeexSBMode*)(st->mode->mode);
low = in;
high = in+st->frame_size;
/* High-band buffering / sync with low band */
/* Compute the two sub-bands by filtering with QMF h0*/
qmf_decomp(in, h0, low, high, st->full_frame_size, QMF_ORDER, st->h0_mem, stack);
#ifndef DISABLE_VBR
if (st->vbr_enabled || st->vad_enabled)
{
/* Need to compute things here before the signal is trashed by the encoder */
/*FIXME: Are the two signals (low, high) in sync? */
e_low = compute_rms16(low, st->frame_size);
e_high = compute_rms16(high, st->frame_size);
}
#endif /* #ifndef DISABLE_VBR */
ALLOC(low_innov_rms, st->nbSubframes, spx_word16_t);
speex_encoder_ctl(st->st_low, SPEEX_SET_INNOVATION_SAVE, low_innov_rms);
/* Encode the narrowband part*/
speex_encode_native(st->st_low, low, bits);
high = high - (st->windowSize-st->frame_size);
SPEEX_COPY(high, st->high, st->windowSize-st->frame_size);
SPEEX_COPY(st->high, &high[st->frame_size], st->windowSize-st->frame_size);
ALLOC(low_pi_gain, st->nbSubframes, spx_word32_t);
ALLOC(low_exc_rms, st->nbSubframes, spx_word16_t);
speex_encoder_ctl(st->st_low, SPEEX_GET_PI_GAIN, low_pi_gain);
speex_encoder_ctl(st->st_low, SPEEX_GET_EXC, low_exc_rms);
speex_encoder_ctl(st->st_low, SPEEX_GET_LOW_MODE, &dtx);
if (dtx==0)
dtx=1;
else
dtx=0;
ALLOC(lpc, st->lpcSize, spx_coef_t);
ALLOC(interp_lpc, st->lpcSize, spx_coef_t);
ALLOC(bw_lpc1, st->lpcSize, spx_coef_t);
ALLOC(bw_lpc2, st->lpcSize, spx_coef_t);
ALLOC(lsp, st->lpcSize, spx_lsp_t);
ALLOC(qlsp, st->lpcSize, spx_lsp_t);
ALLOC(interp_lsp, st->lpcSize, spx_lsp_t);
ALLOC(interp_qlsp, st->lpcSize, spx_lsp_t);
{
VARDECL(spx_word16_t *autocorr);
VARDECL(spx_word16_t *w_sig);
ALLOC(autocorr, st->lpcSize+1, spx_word16_t);
ALLOC(w_sig, st->windowSize, spx_word16_t);
/* Window for analysis */
/* FIXME: This is a kludge */
if (st->subframeSize==80)
{
for (i=0;i<st->windowSize;i++)
w_sig[i] = EXTRACT16(SHR32(MULT16_16(high[i],st->window[i>>1]),SIG_SHIFT));
} else {
for (i=0;i<st->windowSize;i++)
w_sig[i] = EXTRACT16(SHR32(MULT16_16(high[i],st->window[i]),SIG_SHIFT));
}
/* Compute auto-correlation */
_spx_autocorr(w_sig, autocorr, st->lpcSize+1, st->windowSize);
autocorr[0] = ADD16(autocorr[0],MULT16_16_Q15(autocorr[0],st->lpc_floor)); /* Noise floor in auto-correlation domain */
/* Lag windowing: equivalent to filtering in the power-spectrum domain */
for (i=0;i<st->lpcSize+1;i++)
autocorr[i] = MULT16_16_Q14(autocorr[i],st->lagWindow[i]);
/* Levinson-Durbin */
_spx_lpc(lpc, autocorr, st->lpcSize);
}
