ref: e14fe9046fde445108736c6ddbcf4e9c85eaedbd
parent: 1ccfd3cc03edd1760106f10387dc7cf8c49e308f
author: Jean-Marc Valin <[email protected]>
date: Thu Dec 10 19:07:31 EST 2009
New LPC-based PLC code
--- a/libcelt/celt.c
+++ b/libcelt/celt.c
@@ -1214,16 +1214,15 @@
celt_free(st);
}
-/** Handles lost packets by just copying past data with the same
- offset as the last
- pitch period */
-#ifdef NEW_PLC
+#ifndef FIXED_POINT
#include "plc.c"
-#else
+#endif
+#define LPC_ORDER 24
static void celt_decode_lost(CELTDecoder * restrict st, celt_word16 * restrict pcm)
{int c, N;
int pitch_index;
+ int overlap = st->mode->overlap;
celt_word16 fade = Q15ONE;
int i, len;
VARDECL(celt_sig, freq);
@@ -1231,7 +1230,6 @@
int offset;
SAVE_STACK;
N = st->block_size;
- ALLOC(freq,C*N, celt_sig); /**< Interleaved signal MDCTs */
len = N+st->mode->overlap;
@@ -1241,10 +1239,10 @@
celt_word32 tmp=0;
celt_word32 mem0[2]={0,0}; celt_word16 mem1[2]={0,0};- /*find_spectral_pitch(st->mode, st->mode->fft, &st->mode->psy, st->out_mem+MAX_PERIOD-len, st->out_mem, st->mode->window, NULL, len, MAX_PERIOD-len-100, &pitch_index, C);*/
- /* FIXME: Should do a bit of interpolation while decimating */
- pitch_downsample(st->out_mem, pitch_buf, MAX_PERIOD, MAX_PERIOD, C, mem0, mem1);
- pitch_search(st->mode, pitch_buf+((MAX_PERIOD-len)>>1), pitch_buf, len, MAX_PERIOD-len-100, &pitch_index, &tmp);
+ pitch_downsample(st->out_mem, pitch_buf, MAX_PERIOD, MAX_PERIOD,
+ C, mem0, mem1);
+ pitch_search(st->mode, pitch_buf+((MAX_PERIOD-len)>>1), pitch_buf, len,
+ MAX_PERIOD-len-100, &pitch_index, &tmp);
pitch_index = MAX_PERIOD-len-pitch_index;
st->last_pitch_index = pitch_index;
} else {@@ -1256,6 +1254,8 @@
}
offset = MAX_PERIOD-pitch_index;
+#ifdef FIXED_POINT
+ ALLOC(freq,C*N, celt_sig); /**< Interleaved signal MDCTs */
while (offset+len >= MAX_PERIOD)
offset -= pitch_index;
compute_mdcts(st->mode, 0, st->out_mem+offset*C, freq, C);
@@ -1265,7 +1265,79 @@
CELT_MOVE(st->out_mem, st->out_mem+C*N, C*(MAX_PERIOD+st->mode->overlap-N));
/* Compute inverse MDCTs */
compute_inv_mdcts(st->mode, 0, freq, -1, 0, st->out_mem, C);
+#else
+ for (c=0;c<C;c++)
+ {+ float e[MAX_PERIOD];
+ float exc[MAX_PERIOD];
+ float ac[LPC_ORDER+1];
+ float lpc[LPC_ORDER];
+ float decay = 1;
+ celt_word32 mem[LPC_ORDER]={0};+ for (i=0;i<MAX_PERIOD;i++)
+ exc[i] = st->out_mem[i*C+c];
+ _celt_autocorr(exc, ac, st->mode->window, st->mode->overlap,
+ LPC_ORDER, MAX_PERIOD);
+ ac[0] *= 1.0001;
+ _celt_lpc(lpc, ac, LPC_ORDER);
+ fir(exc, lpc, exc, MAX_PERIOD, LPC_ORDER, mem);
+
+ /* Check if the waveform is decaying (and if so how fast) */
+ {+ float E1=0, E2=0;
+ int period;
+ if (pitch_index <= MAX_PERIOD/2)
+ period = pitch_index;
+ else
+ period = MAX_PERIOD/2;
+ for (i=0;i<period;i++)
+ {+ E1 += exc[MAX_PERIOD-period+i]*exc[MAX_PERIOD-period+i];
+ E2 += exc[MAX_PERIOD-2*period+i]*exc[MAX_PERIOD-2*period+i];
+ }
+ decay = sqrt((E1+1)/(E2+1));
+ if (decay > 1)
+ decay = 1;
+ }
+
+ /* Copy excitation, taking decay into account */
+ for (i=0;i<len+st->mode->overlap;i++)
+ {+ if (offset+i >= MAX_PERIOD)
+ {+ offset -= pitch_index;
+ decay *= decay;
+ }
+ e[i] = decay*exc[offset+i];
+ }
+
+ for (i=0;i<MAX_PERIOD+st->mode->overlap-N;i++)
+ st->out_mem[C*i+c] = st->out_mem[C*(N+i)+c];
+
+ iir(e, lpc, e, len+st->mode->overlap, LPC_ORDER, mem);
+
+ /* Apply TDAC to the concealed audio so that it blends with the
+ previous and next frames */
+ for (i=0;i<overlap/2;i++)
+ {+ float tmp1, tmp2;
+ tmp1 = e[i ]*st->mode->window[i ] -
+ e[overlap-i-1]*st->mode->window[overlap-i-1];
+ tmp2 = e[N+overlap-1-i]*st->mode->window[i] +
+ e[N+i ]*st->mode->window[overlap-i-1];
+ tmp1 *= fade;
+ tmp2 *= fade;
+ st->out_mem[C*(MAX_PERIOD+i)+c] = tmp2*st->mode->window[overlap-i-1];
+ st->out_mem[C*(MAX_PERIOD+overlap-i-1)+c] = tmp2*st->mode->window[i];
+ st->out_mem[C*(MAX_PERIOD-N+i)+c] += tmp1*st->mode->window[i];
+ st->out_mem[C*(MAX_PERIOD-N+overlap-i-1)+c] -= tmp1*st->mode->window[overlap-i-1];
+ }
+ for (i=0;i<N-overlap;i++)
+ st->out_mem[C*(MAX_PERIOD-N+overlap+i)+c] = fade*e[overlap+i];
+ }
+#endif
+
for (c=0;c<C;c++)
{int j;
@@ -1282,7 +1354,6 @@
RESTORE_STACK;
}
-#endif
#ifdef FIXED_POINT
int celt_decode(CELTDecoder * restrict st, const unsigned char *data, int len, celt_int16 * restrict pcm)
@@ -1337,8 +1408,6 @@
celt_decode_lost(st, pcm);
RESTORE_STACK;
return 0;
- } else {- st->loss_count = 0;
}
if (len<0) {RESTORE_STACK;
@@ -1427,7 +1496,7 @@
compute_inv_mdcts(st->mode, shortBlocks, freq, transient_time, transient_shift, st->out_mem, C);
deemphasis(st->out_mem, pcm, N, C, preemph, st->preemph_memD);
-
+ st->loss_count = 0;
RESTORE_STACK;
return 0;
}
--- /dev/null
+++ b/libcelt/plc.c
@@ -1,0 +1,125 @@
+
+
+
+
+celt_word32 _celt_lpc(
+celt_word16 *lpc, /* out: [0...p-1] LPC coefficients */
+const celt_word16 *ac, /* in: [0...p] autocorrelation values */
+int p
+)
+{+ int i, j;
+ celt_word16 r;
+ celt_word16 error = ac[0];
+
+ if (ac[0] == 0)
+ {+ for (i = 0; i < p; i++)
+ lpc[i] = 0;
+ return 0;
+ }
+
+ for (i = 0; i < p; i++) {+
+ /* Sum up this iteration's reflection coefficient */
+ celt_word32 rr = NEG32(SHL32(EXTEND32(ac[i + 1]),13));
+ for (j = 0; j < i; j++)
+ rr = SUB32(rr,MULT16_16(lpc[j],ac[i - j]));
+#ifdef FIXED_POINT
+ r = DIV32_16(rr+PSHR32(error,1),ADD16(error,8));
+#else
+ r = rr/(error+.003*ac[0]);
+#endif
+ /* Update LPC coefficients and total error */
+ lpc[i] = r;
+ for (j = 0; j < i>>1; j++)
+ {+ celt_word16 tmp = lpc[j];
+ lpc[j] = MAC16_16_P13(lpc[j],r,lpc[i-1-j]);
+ lpc[i-1-j] = MAC16_16_P13(lpc[i-1-j],r,tmp);
+ }
+ if (i & 1)
+ lpc[j] = MAC16_16_P13(lpc[j],lpc[j],r);
+
+ error = SUB16(error,MULT16_16_Q13(r,MULT16_16_Q13(error,r)));
+ }
+ return error;
+}
+
+void fir(const celt_word16 *x,
+ const celt_word16 *num,
+ celt_word16 *y,
+ int N,
+ int ord,
+ celt_word32 *mem)
+{+ int i,j;
+
+ for (i=0;i<N;i++)
+ {+ float sum = x[i];
+ for (j=0;j<ord;j++)
+ {+ sum += num[j]*mem[j];
+ }
+ for (j=ord-1;j>=1;j--)
+ {+ mem[j]=mem[j-1];
+ }
+ mem[0] = x[i];
+ y[i] = sum;
+ }
+}
+
+void iir(const celt_word16 *x,
+ const celt_word16 *den,
+ celt_word16 *y,
+ int N,
+ int ord,
+ celt_word32 *mem)
+{+ int i,j;
+ for (i=0;i<N;i++)
+ {+ float sum = x[i];
+ for (j=0;j<ord;j++)
+ {+ sum -= den[j]*mem[j];
+ }
+ for (j=ord-1;j>=1;j--)
+ {+ mem[j]=mem[j-1];
+ }
+ mem[0] = sum;
+ y[i] = sum;
+ }
+}
+
+void _celt_autocorr(
+ const celt_word16 *x, /* in: [0...n-1] samples x */
+ float *ac, /* out: [0...lag-1] ac values */
+ const float *window,
+ int overlap,
+ int lag,
+ int n
+ )
+{+ float d;
+ int i;
+ float xx[n];
+ for (i=0;i<n;i++)
+ xx[i] = x[i];
+ for (i=0;i<overlap;i++)
+ {+ xx[i] *= window[i];
+ xx[n-i-1] *= window[i];
+ }
+ while (lag>=0)
+ {+ for (i = lag, d = 0; i < n; i++)
+ d += x[i] * x[i-lag];
+ ac[lag] = d;
+ lag--;
+ }
+ ac[0] += 10;
+}