New LPC-based PLC code
This commit is contained in:
Jean-Marc Valin
parent
1ccfd3cc03
commit
e14fe9046f
2 changed files with 208 additions and 14 deletions
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@ -1214,16 +1214,15 @@ void celt_decoder_destroy(CELTDecoder *st)
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celt_free(st);
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}
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/** Handles lost packets by just copying past data with the same
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offset as the last
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pitch period */
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#ifdef NEW_PLC
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#ifndef FIXED_POINT
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#include "plc.c"
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#else
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#endif
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#define LPC_ORDER 24
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static void celt_decode_lost(CELTDecoder * restrict st, celt_word16 * restrict pcm)
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{
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int c, N;
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int pitch_index;
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int overlap = st->mode->overlap;
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celt_word16 fade = Q15ONE;
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int i, len;
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VARDECL(celt_sig, freq);
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@ -1231,7 +1230,6 @@ static void celt_decode_lost(CELTDecoder * restrict st, celt_word16 * restrict p
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int offset;
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SAVE_STACK;
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N = st->block_size;
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ALLOC(freq,C*N, celt_sig); /**< Interleaved signal MDCTs */
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len = N+st->mode->overlap;
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@ -1241,10 +1239,10 @@ static void celt_decode_lost(CELTDecoder * restrict st, celt_word16 * restrict p
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celt_word32 tmp=0;
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celt_word32 mem0[2]={0,0};
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celt_word16 mem1[2]={0,0};
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/*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);*/
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/* FIXME: Should do a bit of interpolation while decimating */
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pitch_downsample(st->out_mem, pitch_buf, MAX_PERIOD, MAX_PERIOD, C, mem0, mem1);
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pitch_search(st->mode, pitch_buf+((MAX_PERIOD-len)>>1), pitch_buf, len, MAX_PERIOD-len-100, &pitch_index, &tmp);
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pitch_downsample(st->out_mem, pitch_buf, MAX_PERIOD, MAX_PERIOD,
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C, mem0, mem1);
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pitch_search(st->mode, pitch_buf+((MAX_PERIOD-len)>>1), pitch_buf, len,
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MAX_PERIOD-len-100, &pitch_index, &tmp);
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pitch_index = MAX_PERIOD-len-pitch_index;
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st->last_pitch_index = pitch_index;
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} else {
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@ -1256,6 +1254,8 @@ static void celt_decode_lost(CELTDecoder * restrict st, celt_word16 * restrict p
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}
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offset = MAX_PERIOD-pitch_index;
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#ifdef FIXED_POINT
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ALLOC(freq,C*N, celt_sig); /**< Interleaved signal MDCTs */
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while (offset+len >= MAX_PERIOD)
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offset -= pitch_index;
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compute_mdcts(st->mode, 0, st->out_mem+offset*C, freq, C);
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@ -1265,6 +1265,78 @@ static void celt_decode_lost(CELTDecoder * restrict st, celt_word16 * restrict p
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CELT_MOVE(st->out_mem, st->out_mem+C*N, C*(MAX_PERIOD+st->mode->overlap-N));
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/* Compute inverse MDCTs */
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compute_inv_mdcts(st->mode, 0, freq, -1, 0, st->out_mem, C);
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#else
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for (c=0;c<C;c++)
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{
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float e[MAX_PERIOD];
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float exc[MAX_PERIOD];
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float ac[LPC_ORDER+1];
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float lpc[LPC_ORDER];
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float decay = 1;
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celt_word32 mem[LPC_ORDER]={0};
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for (i=0;i<MAX_PERIOD;i++)
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exc[i] = st->out_mem[i*C+c];
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_celt_autocorr(exc, ac, st->mode->window, st->mode->overlap,
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LPC_ORDER, MAX_PERIOD);
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ac[0] *= 1.0001;
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_celt_lpc(lpc, ac, LPC_ORDER);
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fir(exc, lpc, exc, MAX_PERIOD, LPC_ORDER, mem);
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/* Check if the waveform is decaying (and if so how fast) */
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{
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float E1=0, E2=0;
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int period;
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if (pitch_index <= MAX_PERIOD/2)
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period = pitch_index;
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else
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period = MAX_PERIOD/2;
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for (i=0;i<period;i++)
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{
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E1 += exc[MAX_PERIOD-period+i]*exc[MAX_PERIOD-period+i];
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E2 += exc[MAX_PERIOD-2*period+i]*exc[MAX_PERIOD-2*period+i];
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}
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decay = sqrt((E1+1)/(E2+1));
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if (decay > 1)
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decay = 1;
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}
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/* Copy excitation, taking decay into account */
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for (i=0;i<len+st->mode->overlap;i++)
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{
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if (offset+i >= MAX_PERIOD)
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{
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offset -= pitch_index;
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decay *= decay;
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}
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e[i] = decay*exc[offset+i];
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}
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for (i=0;i<MAX_PERIOD+st->mode->overlap-N;i++)
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st->out_mem[C*i+c] = st->out_mem[C*(N+i)+c];
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iir(e, lpc, e, len+st->mode->overlap, LPC_ORDER, mem);
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/* Apply TDAC to the concealed audio so that it blends with the
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previous and next frames */
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for (i=0;i<overlap/2;i++)
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{
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float tmp1, tmp2;
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tmp1 = e[i ]*st->mode->window[i ] -
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e[overlap-i-1]*st->mode->window[overlap-i-1];
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tmp2 = e[N+overlap-1-i]*st->mode->window[i] +
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e[N+i ]*st->mode->window[overlap-i-1];
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tmp1 *= fade;
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tmp2 *= fade;
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st->out_mem[C*(MAX_PERIOD+i)+c] = tmp2*st->mode->window[overlap-i-1];
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st->out_mem[C*(MAX_PERIOD+overlap-i-1)+c] = tmp2*st->mode->window[i];
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st->out_mem[C*(MAX_PERIOD-N+i)+c] += tmp1*st->mode->window[i];
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st->out_mem[C*(MAX_PERIOD-N+overlap-i-1)+c] -= tmp1*st->mode->window[overlap-i-1];
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}
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for (i=0;i<N-overlap;i++)
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st->out_mem[C*(MAX_PERIOD-N+overlap+i)+c] = fade*e[overlap+i];
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}
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#endif
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for (c=0;c<C;c++)
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{
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@ -1282,7 +1354,6 @@ static void celt_decode_lost(CELTDecoder * restrict st, celt_word16 * restrict p
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RESTORE_STACK;
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}
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#endif
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#ifdef FIXED_POINT
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int celt_decode(CELTDecoder * restrict st, const unsigned char *data, int len, celt_int16 * restrict pcm)
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@ -1337,8 +1408,6 @@ int celt_decode_float(CELTDecoder * restrict st, const unsigned char *data, int
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celt_decode_lost(st, pcm);
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RESTORE_STACK;
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return 0;
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} else {
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st->loss_count = 0;
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}
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if (len<0) {
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RESTORE_STACK;
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@ -1427,7 +1496,7 @@ int celt_decode_float(CELTDecoder * restrict st, const unsigned char *data, int
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compute_inv_mdcts(st->mode, shortBlocks, freq, transient_time, transient_shift, st->out_mem, C);
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deemphasis(st->out_mem, pcm, N, C, preemph, st->preemph_memD);
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st->loss_count = 0;
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RESTORE_STACK;
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return 0;
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}
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125
libcelt/plc.c
Normal file
125
libcelt/plc.c
Normal file
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@ -0,0 +1,125 @@
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celt_word32 _celt_lpc(
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celt_word16 *lpc, /* out: [0...p-1] LPC coefficients */
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const celt_word16 *ac, /* in: [0...p] autocorrelation values */
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int p
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)
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{
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int i, j;
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celt_word16 r;
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celt_word16 error = ac[0];
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if (ac[0] == 0)
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{
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for (i = 0; i < p; i++)
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lpc[i] = 0;
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return 0;
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}
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for (i = 0; i < p; i++) {
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/* Sum up this iteration's reflection coefficient */
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celt_word32 rr = NEG32(SHL32(EXTEND32(ac[i + 1]),13));
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for (j = 0; j < i; j++)
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rr = SUB32(rr,MULT16_16(lpc[j],ac[i - j]));
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#ifdef FIXED_POINT
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r = DIV32_16(rr+PSHR32(error,1),ADD16(error,8));
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#else
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r = rr/(error+.003*ac[0]);
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#endif
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/* Update LPC coefficients and total error */
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lpc[i] = r;
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for (j = 0; j < i>>1; j++)
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{
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celt_word16 tmp = lpc[j];
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lpc[j] = MAC16_16_P13(lpc[j],r,lpc[i-1-j]);
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lpc[i-1-j] = MAC16_16_P13(lpc[i-1-j],r,tmp);
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}
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if (i & 1)
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lpc[j] = MAC16_16_P13(lpc[j],lpc[j],r);
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error = SUB16(error,MULT16_16_Q13(r,MULT16_16_Q13(error,r)));
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}
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return error;
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}
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void fir(const celt_word16 *x,
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const celt_word16 *num,
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celt_word16 *y,
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int N,
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int ord,
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celt_word32 *mem)
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{
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int i,j;
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for (i=0;i<N;i++)
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{
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float sum = x[i];
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for (j=0;j<ord;j++)
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{
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sum += num[j]*mem[j];
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}
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for (j=ord-1;j>=1;j--)
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{
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mem[j]=mem[j-1];
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}
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mem[0] = x[i];
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y[i] = sum;
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}
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}
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void iir(const celt_word16 *x,
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const celt_word16 *den,
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celt_word16 *y,
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int N,
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int ord,
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celt_word32 *mem)
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{
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int i,j;
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for (i=0;i<N;i++)
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{
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float sum = x[i];
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for (j=0;j<ord;j++)
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{
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sum -= den[j]*mem[j];
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}
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for (j=ord-1;j>=1;j--)
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{
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mem[j]=mem[j-1];
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}
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mem[0] = sum;
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y[i] = sum;
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}
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}
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void _celt_autocorr(
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const celt_word16 *x, /* in: [0...n-1] samples x */
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float *ac, /* out: [0...lag-1] ac values */
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const float *window,
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int overlap,
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int lag,
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int n
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)
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{
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float d;
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int i;
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float xx[n];
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for (i=0;i<n;i++)
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xx[i] = x[i];
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for (i=0;i<overlap;i++)
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{
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xx[i] *= window[i];
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xx[n-i-1] *= window[i];
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}
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while (lag>=0)
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{
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for (i = lag, d = 0; i < n; i++)
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d += x[i] * x[i-lag];
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ac[lag] = d;
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lag--;
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}
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ac[0] += 10;
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}
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