static void preprocess_analysis(SpeexPreprocessState *st, spx_int16_t *x) { int i; int N = st->ps_size; int N3 = 2*N - st->frame_size; int N4 = st->frame_size - N3; float *ps=st->ps; /* 'Build' input frame */ for (i=0;i<N3;i++) st->frame[i]=st->inbuf[i]; for (i=0;i<st->frame_size;i++) st->frame[N3+i]=x[i]; /* Update inbuf */ for (i=0;i<N3;i++) st->inbuf[i]=x[N4+i]; /* Windowing */ for (i=0;i<2*N;i++) st->frame[i] *= st->window[i]; /* Perform FFT */ spx_drft_forward(st->fft_lookup, st->frame); /* Power spectrum */ ps[0]=1; for (i=1;i<N;i++) ps[i]=1+st->frame[2*i-1]*st->frame[2*i-1] + st->frame[2*i]*st->frame[2*i]; }
/* 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 }
void compute_curve(VorbisPsy *psy, float *audio, float *curve) { int i; float work[psy->n]; float scale=4.f/psy->n; float scale_dB; scale_dB=todB(scale); /* window the PCM data; use a BH4 window, not vorbis */ for(i=0;i<psy->n;i++) work[i]=audio[i] * psy->window[i]; { static int seq=0; //_analysis_output("win",seq,work,psy->n,0,0); seq++; } /* FFT yields more accurate tonal estimation (not phase sensitive) */ spx_drft_forward(&psy->lookup,work); /* magnitudes */ work[0]=scale_dB+todB(work[0]); for(i=1;i<psy->n-1;i+=2){ float temp = work[i]*work[i] + work[i+1]*work[i+1]; work[(i+1)>>1] = scale_dB+.5f * todB(temp); } /* derive a noise curve */ _vp_noisemask(psy,work,curve); #define SIDEL 12 for (i=0;i<SIDEL;i++) { curve[i]=curve[SIDEL]; } #define SIDEH 12 for (i=0;i<SIDEH;i++) { curve[(psy->n>>1)-i-1]=curve[(psy->n>>1)-SIDEH]; } for(i=0;i<((psy->n)>>1);i++) curve[i] = fromdB(1.2*curve[i]+.2*i); //curve[i] = fromdB(0.8*curve[i]+.35*i); //curve[i] = fromdB(0.9*curve[i])*pow(1.0*i+45,1.3); }
/** Performs echo cancellation on a frame */ void speex_echo_cancel(SpeexEchoState *st, short *ref, short *echo, short *out, float *Yout) { int i,j,m; int N,M; float scale; float ESR; float SER; float Sry=0,Srr=0,Syy=0,Sey=0,See=0,Sxx=0; float leak_estimate; leak_estimate = .1+(.9/(1+2*st->sum_adapt)); N = st->window_size; M = st->M; scale = 1.0f/N; st->cancel_count++; /* Copy input data to buffer */ for (i=0; i<st->frame_size; i++) { st->x[i] = st->x[i+st->frame_size]; st->x[i+st->frame_size] = echo[i]; st->d[i] = st->d[i+st->frame_size]; st->d[i+st->frame_size] = ref[i]; } /* Shift memory: this could be optimized eventually*/ for (i=0; i<N*(M-1); i++) st->X[i]=st->X[i+N]; /* Copy new echo frame */ for (i=0; i<N; i++) st->X[(M-1)*N+i]=st->x[i]; /* Convert x (echo input) to frequency domain */ spx_drft_forward(st->fft_lookup, &st->X[(M-1)*N]); /* Compute filter response Y */ for (i=0; i<N; i++) st->Y[i] = 0; for (j=0; j<M; j++) spectral_mul_accum(&st->X[j*N], &st->W[j*N], st->Y, N); /* Convert Y (filter response) to time domain */ for (i=0; i<N; i++) st->y[i] = st->Y[i]; spx_drft_backward(st->fft_lookup, st->y); for (i=0; i<N; i++) st->y[i] *= scale; /* Transform d (reference signal) to frequency domain */ for (i=0; i<N; i++) st->D[i]=st->d[i]; spx_drft_forward(st->fft_lookup, st->D); /* Compute error signal (signal with echo removed) */ for (i=0; i<st->frame_size; i++) { float tmp_out; tmp_out = (float)ref[i] - st->y[i+st->frame_size]; st->E[i] = 0; st->E[i+st->frame_size] = tmp_out; /* Saturation */ if (tmp_out>32767) tmp_out = 32767; else if (tmp_out<-32768) tmp_out = -32768; out[i] = tmp_out; } /* This bit of code provides faster adaptation by doing a projection of the previous gradient on the "MMSE surface" */ if (1) { float Sge, Sgg, Syy; float gain; Syy = inner_prod(st->y+st->frame_size, st->y+st->frame_size, st->frame_size); for (i=0; i<N; i++) st->Y2[i] = 0; for (j=0; j<M; j++) spectral_mul_accum(&st->X[j*N], &st->PHI[j*N], st->Y2, N); for (i=0; i<N; i++) st->y2[i] = st->Y2[i]; spx_drft_backward(st->fft_lookup, st->y2); for (i=0; i<N; i++) st->y2[i] *= scale; Sge = inner_prod(st->y2+st->frame_size, st->E+st->frame_size, st->frame_size); Sgg = inner_prod(st->y2+st->frame_size, st->y2+st->frame_size, st->frame_size); /* Compute projection gain */ gain = Sge/(N+.03*Syy+Sgg); if (gain>2) gain = 2; if (gain < -2) gain = -2; /* Apply gain to weights, echo estimates, output */ for (i=0; i<N; i++) st->Y[i] += gain*st->Y2[i]; for (i=0; i<st->frame_size; i++) { st->y[i+st->frame_size] += gain*st->y2[i+st->frame_size]; st->E[i+st->frame_size] -= gain*st->y2[i+st->frame_size]; } for (i=0; i<M*N; i++) st->W[i] += gain*st->PHI[i]; } /* Compute power spectrum of output (D-Y) and filter response (Y) */ for (i=0; i<N; i++) st->D[i] -= st->Y[i]; power_spectrum(st->D, st->Rf, N); power_spectrum(st->Y, st->Yf, N); /* Compute frequency-domain adaptation mask */ for (j=0; j<=st->frame_size; j++) { float r; r = leak_estimate*st->Yf[j] / (1+st->Rf[j]); if (r>1) r = 1; st->fratio[j] = r; } /* Compute a bunch of correlations */ Sry = inner_prod(st->y+st->frame_size, st->d+st->frame_size, st->frame_size); Sey = inner_prod(st->y+st->frame_size, st->E+st->frame_size, st->frame_size); See = inner_prod(st->E+st->frame_size, st->E+st->frame_size, st->frame_size); Syy = inner_prod(st->y+st->frame_size, st->y+st->frame_size, st->frame_size); Srr = inner_prod(st->d+st->frame_size, st->d+st->frame_size, st->frame_size); Sxx = inner_prod(st->x+st->frame_size, st->x+st->frame_size, st->frame_size); /* Compute smoothed cross-correlation and energy */ st->Sey = .98*st->Sey + .02*Sey; st->Syy = .98*st->Syy + .02*Syy; st->See = .98*st->See + .02*See; /* Check if filter is completely mis-adapted (if so, reset filter) */ if (st->Sey/(1+st->Syy + .01*st->See) < -1) { /*fprintf (stderr, "reset at %d\n", st->cancel_count);*/ speex_echo_state_reset(st); return; } SER = Srr / (1+Sxx); ESR = leak_estimate*Syy / (1+See); if (ESR>1) ESR = 1; #if 1 /* If over-cancellation (creating echo with 180 phase) damp filter */ if (st->Sey/(1+st->Syy) < -.1 && (ESR > .3)) { for (i=0; i<M*N; i++) st->W[i] *= .95; st->Sey *= .5; /*fprintf (stderr, "corrected down\n");*/ } #endif #if 1 /* If under-cancellation (leaving echo with 0 phase) scale filter up */ if (st->Sey/(1+st->Syy) > .1 && (ESR > .1 || SER < 10)) { for (i=0; i<M*N; i++) st->W[i] *= 1.05; st->Sey *= .5; /*fprintf (stderr, "corrected up %d\n", st->cancel_count);*/ } #endif /* We consider that the filter is adapted if the following is true*/ if (ESR>.6 && st->sum_adapt > 1) { /*if (!st->adapted) fprintf(stderr, "Adapted at %d %f\n", st->cancel_count, st->sum_adapt);*/ st->adapted = 1; } /* Update frequency-dependent energy ratio with the total energy ratio */ for (i=0; i<=st->frame_size; i++) { st->fratio[i] = (.2*ESR+.8*min(.005+ESR,st->fratio[i])); } if (st->adapted) { st->adapt_rate = .95f/(2+M); } else { /* Temporary adaption rate if filter is not adapted correctly */ if (SER<.1) st->adapt_rate =.8/(2+M); else if (SER<1) st->adapt_rate =.4/(2+M); else if (SER<10) st->adapt_rate =.2/(2+M); else if (SER<30) st->adapt_rate =.08/(2+M); else st->adapt_rate = 0; } /* How much have we adapted so far? */ st->sum_adapt += st->adapt_rate; /* Compute echo power in each frequency bin */ { float ss = 1.0f/st->cancel_count; if (ss < .3/M) ss=.3/M; power_spectrum(&st->X[(M-1)*N], st->Xf, N); /* Smooth echo energy estimate over time */ for (j=0; j<=st->frame_size; j++) st->power[j] = (1-ss)*st->power[j] + ss*st->Xf[j]; /* Combine adaptation rate to the the inverse energy estimate */ if (st->adapted) { /* If filter is adapted, include the frequency-dependent ratio too */ for (i=0; i<=st->frame_size; i++) st->power_1[i] = st->adapt_rate*st->fratio[i] /(1.f+st->power[i]); } else { for (i=0; i<=st->frame_size; i++) st->power_1[i] = st->adapt_rate/(1.f+st->power[i]); } } /* Convert error to frequency domain */ spx_drft_forward(st->fft_lookup, st->E); /* Do some regularization (prevents problems when system is ill-conditoned) */ for (m=0; m<M; m++) for (i=0; i<N; i++) st->W[m*N+i] *= 1-st->regul[i]*ESR; /* Compute weight gradient */ for (j=0; j<M; j++) { weighted_spectral_mul_conj(st->power_1, &st->X[j*N], st->E, st->PHI+N*j, N); } /* Gradient descent */ for (i=0; i<M*N; i++) st->W[i] += st->PHI[i]; /* AUMDF weight constraint */ for (j=0; j<M; j++) { /* Remove the "if" to make this an MDF filter */ if (st->cancel_count%M == j) { spx_drft_backward(st->fft_lookup, &st->W[j*N]); for (i=0; i<N; i++) st->W[j*N+i]*=scale; for (i=st->frame_size; i<N; i++) { st->W[j*N+i]=0; } spx_drft_forward(st->fft_lookup, &st->W[j*N]); } } /* Compute spectrum of estimated echo for use in an echo post-filter (if necessary)*/ if (Yout) { if (st->adapted) { /* If the filter is adapted, take the filtered echo */ for (i=0; i<st->frame_size; i++) st->last_y[i] = st->last_y[st->frame_size+i]; for (i=0; i<st->frame_size; i++) st->last_y[st->frame_size+i] = st->y[st->frame_size+i]; } else { /* If filter isn't adapted yet, all we can do is take the echo signal directly */ for (i=0; i<N; i++) st->last_y[i] = st->x[i]; } /* Apply hanning window (should pre-compute it)*/ for (i=0; i<N; i++) st->Yps[i] = (.5-.5*cos(2*M_PI*i/N))*st->last_y[i]; /* Compute power spectrum of the echo */ spx_drft_forward(st->fft_lookup, st->Yps); power_spectrum(st->Yps, st->Yps, N); /* Estimate residual echo */ for (i=0; i<=st->frame_size; i++) Yout[i] = 2*leak_estimate*st->Yps[i]; } }