nb_celp.c

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   /* First, transmit a zero for narrowband */
   speex_bits_pack(bits, 0, 1);

   /* Transmit the sub-mode we use for this frame */
   speex_bits_pack(bits, st->submodeID, NB_SUBMODE_BITS);


   /* If null mode (no transmission), just set a couple things to zero*/
   if (st->submodes[st->submodeID] == NULL)
   {
      for (i=0;i<st->frameSize;i++)
         st->exc[i]=st->exc2[i]=st->sw[i]=0;

      for (i=0;i<st->lpcSize;i++)
         st->mem_sw[i]=0;
      st->first=1;
      st->bounded_pitch = 1;

      /* Final signal synthesis from excitation */
      iir_mem2(st->exc, st->interp_qlpc, st->frame, st->frameSize, st->lpcSize, st->mem_sp);

      in[0] = st->frame[0] + st->preemph*st->pre_mem2;
      for (i=1;i<st->frameSize;i++)
         in[i]=st->frame[i] + st->preemph*in[i-1];
      st->pre_mem2=in[st->frameSize-1];

      return 0;

   }

   /* LSP Quantization */
   if (st->first)
   {
      for (i=0;i<st->lpcSize;i++)
         st->old_lsp[i] = st->lsp[i];
   }


   /*Quantize LSPs*/
#if 1 /*0 for unquantized*/
   SUBMODE(lsp_quant)(st->lsp, st->qlsp, st->lpcSize, bits);
#else
   for (i=0;i<st->lpcSize;i++)
     st->qlsp[i]=st->lsp[i];
#endif

   /*If we use low bit-rate pitch mode, transmit open-loop pitch*/
   if (SUBMODE(lbr_pitch)!=-1)
   {
      speex_bits_pack(bits, ol_pitch-st->min_pitch, 7);
   } 
   
   if (SUBMODE(forced_pitch_gain))
   {
      int quant;
      quant = (int)floor(.5+15*ol_pitch_coef);
      if (quant>15)
         quant=0;
      if (quant<0)
         quant=0;
      speex_bits_pack(bits, quant, 4);
      ol_pitch_coef=0.066667*quant;
   }
   
   
   /*Quantize and transmit open-loop excitation gain*/
   {
      int qe = (int)(floor(3.5*log(ol_gain)));
      if (qe<0)
         qe=0;
      if (qe>31)
         qe=31;
      ol_gain = exp(qe/3.5);
      speex_bits_pack(bits, qe, 5);
   }

   /* Special case for first frame */
   if (st->first)
   {
      for (i=0;i<st->lpcSize;i++)
         st->old_qlsp[i] = st->qlsp[i];
   }

   /* Filter response */
   res = PUSH(stack, st->subframeSize, float);
   /* Target signal */
   target = PUSH(stack, st->subframeSize, float);
   syn_resp = PUSH(stack, st->subframeSize, float);
   mem = PUSH(stack, st->lpcSize, float);
   orig = PUSH(stack, st->frameSize, float);
   for (i=0;i<st->frameSize;i++)
      orig[i]=st->frame[i];

   /* Loop on sub-frames */
   for (sub=0;sub<st->nbSubframes;sub++)
   {
      float tmp;
      int   offset;
      float *sp, *sw, *exc, *exc2;
      int pitch;

      /* Offset relative to start of frame */
      offset = st->subframeSize*sub;
      /* Original signal */
      sp=st->frame+offset;
      /* Excitation */
      exc=st->exc+offset;
      /* Weighted signal */
      sw=st->sw+offset;

      exc2=st->exc2+offset;


      /* LSP interpolation (quantized and unquantized) */
      tmp = (1.0 + sub)/st->nbSubframes;
      for (i=0;i<st->lpcSize;i++)
         st->interp_lsp[i] = (1-tmp)*st->old_lsp[i] + tmp*st->lsp[i];
      for (i=0;i<st->lpcSize;i++)
         st->interp_qlsp[i] = (1-tmp)*st->old_qlsp[i] + tmp*st->qlsp[i];

      /* Make sure the filters are stable */
      lsp_enforce_margin(st->interp_lsp, st->lpcSize, .002);
      lsp_enforce_margin(st->interp_qlsp, st->lpcSize, .002);

      /* Compute interpolated LPCs (quantized and unquantized) */
      for (i=0;i<st->lpcSize;i++)
         st->interp_lsp[i] = cos(st->interp_lsp[i]);
      lsp_to_lpc(st->interp_lsp, st->interp_lpc, st->lpcSize,stack);

      for (i=0;i<st->lpcSize;i++)
         st->interp_qlsp[i] = cos(st->interp_qlsp[i]);
      lsp_to_lpc(st->interp_qlsp, st->interp_qlpc, st->lpcSize, stack);

      /* Compute analysis filter gain at w=pi (for use in SB-CELP) */
      tmp=1;
      st->pi_gain[sub]=0;
      for (i=0;i<=st->lpcSize;i++)
      {
         st->pi_gain[sub] += tmp*st->interp_qlpc[i];
         tmp = -tmp;
      }

      /* Compute bandwidth-expanded (unquantized) LPCs for perceptual weighting */
      bw_lpc(st->gamma1, st->interp_lpc, st->bw_lpc1, st->lpcSize);
      if (st->gamma2>=0)
         bw_lpc(st->gamma2, st->interp_lpc, st->bw_lpc2, st->lpcSize);
      else
      {
         st->bw_lpc2[0]=1;
         st->bw_lpc2[1]=-st->preemph;
         for (i=2;i<=st->lpcSize;i++)
            st->bw_lpc2[i]=0;
      }

      /* Compute impulse response of A(z/g1) / ( A(z)*A(z/g2) )*/
      for (i=0;i<st->subframeSize;i++)
         exc[i]=0;
      exc[0]=1;
      syn_percep_zero(exc, st->interp_qlpc, st->bw_lpc1, st->bw_lpc2, syn_resp, st->subframeSize, st->lpcSize, stack);

      /* Reset excitation */
      for (i=0;i<st->subframeSize;i++)
         exc[i]=0;
      for (i=0;i<st->subframeSize;i++)
         exc2[i]=0;

      /* Compute zero response of A(z/g1) / ( A(z/g2) * A(z) ) */
      for (i=0;i<st->lpcSize;i++)
         mem[i]=st->mem_sp[i];
      iir_mem2(exc, st->interp_qlpc, exc, st->subframeSize, st->lpcSize, mem);
      
      for (i=0;i<st->lpcSize;i++)
         mem[i]=st->mem_sw[i];
      filter_mem2(exc, st->bw_lpc1, st->bw_lpc2, res, st->subframeSize, st->lpcSize, mem);
      
      /* Compute weighted signal */
      for (i=0;i<st->lpcSize;i++)
         mem[i]=st->mem_sw[i];
      filter_mem2(sp, st->bw_lpc1, st->bw_lpc2, sw, st->subframeSize, st->lpcSize, mem);
      
      /* Compute target signal */
      for (i=0;i<st->subframeSize;i++)
         target[i]=sw[i]-res[i];

      for (i=0;i<st->subframeSize;i++)
         exc[i]=exc2[i]=0;

      /* If we have a long-term predictor (otherwise, something's wrong) */
      if (SUBMODE(ltp_quant))
      {
         int pit_min, pit_max;
         /* Long-term prediction */
         if (SUBMODE(lbr_pitch) != -1)
         {
            /* Low bit-rate pitch handling */
            int margin;
            margin = SUBMODE(lbr_pitch);
            if (margin)
            {
               if (ol_pitch < st->min_pitch+margin-1)
                  ol_pitch=st->min_pitch+margin-1;
               if (ol_pitch > st->max_pitch-margin)
                  ol_pitch=st->max_pitch-margin;
               pit_min = ol_pitch-margin+1;
               pit_max = ol_pitch+margin;
            } else {
               pit_min=pit_max=ol_pitch;
            }
         } else {
            pit_min = st->min_pitch;
            pit_max = st->max_pitch;
         }
         
         /* Force pitch to use only the current frame if needed */
         if (st->bounded_pitch && pit_max>offset)
            pit_max=offset;

         /* Perform pitch search */
         pitch = SUBMODE(ltp_quant)(target, sw, st->interp_qlpc, st->bw_lpc1, st->bw_lpc2,
                                    exc, SUBMODE(ltp_params), pit_min, pit_max, ol_pitch_coef,
                                    st->lpcSize, st->subframeSize, bits, stack, 
                                    exc2, syn_resp, st->complexity);

         st->pitch[sub]=pitch;
      } else {
         speex_error ("No pitch prediction, what's wrong");
      }

      /* Update target for adaptive codebook contribution */
      syn_percep_zero(exc, st->interp_qlpc, st->bw_lpc1, st->bw_lpc2, res, st->subframeSize, st->lpcSize, stack);
      for (i=0;i<st->subframeSize;i++)
         target[i]-=res[i];


      /* Quantization of innovation */
      {
         float *innov;
         float ener=0, ener_1;

         innov = st->innov+sub*st->subframeSize;
         for (i=0;i<st->subframeSize;i++)
            innov[i]=0;
         
         residue_percep_zero(target, st->interp_qlpc, st->bw_lpc1, st->bw_lpc2, st->buf2, st->subframeSize, st->lpcSize, stack);
         for (i=0;i<st->subframeSize;i++)
            ener+=st->buf2[i]*st->buf2[i];
         ener=sqrt(.1+ener/st->subframeSize);
         /*for (i=0;i<st->subframeSize;i++)
            printf ("%f\n", st->buf2[i]/ener);
         */
         
         ener /= ol_gain;

         /* Calculate gain correction for the sub-frame (if any) */
         if (SUBMODE(have_subframe_gain)) 
         {
            int qe;
            ener=log(ener);
            if (SUBMODE(have_subframe_gain)==3)
            {
               qe = vq_index(&ener, exc_gain_quant_scal3, 1, 8);
               speex_bits_pack(bits, qe, 3);
               ener=exc_gain_quant_scal3[qe];
            } else {
               qe = vq_index(&ener, exc_gain_quant_scal1, 1, 2);
               speex_bits_pack(bits, qe, 1);
               ener=exc_gain_quant_scal1[qe];               
            }
            ener=exp(ener);
         } else {
            ener=1;
         }

         ener*=ol_gain;

         /*printf ("%f %f\n", ener, ol_gain);*/

         ener_1 = 1/ener;

         /* Normalize innovation */
         for (i=0;i<st->subframeSize;i++)
            target[i]*=ener_1;
         
         /* Quantize innovation */
         if (SUBMODE(innovation_quant))
         {
            /* Codebook search */
            SUBMODE(innovation_quant)(target, st->interp_qlpc, st->bw_lpc1, st->bw_lpc2, 
                                      SUBMODE(innovation_params), st->lpcSize, st->subframeSize, 
                                      innov, syn_resp, bits, stack, st->complexity);
            
            /* De-normalize innovation and update excitation */
            for (i=0;i<st->subframeSize;i++)
               innov[i]*=ener;
            for (i=0;i<st->subframeSize;i++)
               exc[i] += innov[i];
         } else {
            speex_error("No fixed codebook");
         }

         /* In some (rare) modes, we do a second search (more bits) to reduce noise even more */
         if (SUBMODE(double_codebook)) {
            char *tmp_stack=stack;
            float *innov2 = PUSH(tmp_stack, st->subframeSize, float);
            for (i=0;i<st->subframeSize;i++)
               innov2[i]=0;
            for (i=0;i<st->subframeSize;i++)
               target[i]*=2.2;
            SUBMODE(innovation_quant)(target, st->interp_qlpc, st->bw_lpc1, st->bw_lpc2, 
                                      SUBMODE(innovation_params), st->lpcSize, st->subframeSize, 
                                      innov2, syn_resp, bits, tmp_stack, st->complexity);
            for (i=0;i<st->subframeSize;i++)
               innov2[i]*=ener*(1/2.2);
            for (i=0;i<st->subframeSize;i++)
               exc[i] += innov2[i];
         }

         for (i=0;i<st->subframeSize;i++)
            target[i]*=ener;

      }

      /*Keep the previous memory*/
      for (i=0;i<st->lpcSize;i++)
         mem[i]=st->mem_sp[i];
      /* Final signal synthesis from excitation */
      iir_mem2(exc, st->interp_qlpc, sp, st->subframeSize, st->lpcSize, st->mem_sp);

      /* Compute weighted signal again, from synthesized speech (not sure it's the right thing) */
      filter_mem2(sp, st->bw_lpc1, st->bw_lpc2, sw, st->subframeSize, st->lpcSize, st->mem_sw);
      for (i=0;i<st->subframeSize;i++)
         exc2[i]=exc[i];
   }

   /* Store the LSPs for interpolation in the next frame */
   if (st->submodeID>=1)
   {
      for (i=0;i<st->lpcSize;i++)
         st->old_lsp[i] = st->lsp[i];
      for (i=0;i<st->lpcSize;i++)
         st->old_qlsp[i] = st->qlsp[i];
   }

   if (st->submodeID==1)
   {
      if (st->dtx_count)
         speex_bits_pack(bits, 15, 4);
      else
         speex_bits_pack(bits, 0, 4);
   }

   /* The next frame will not be the first (Duh!) */
   st->first = 0;

   {
      float ener=0, err=0;
      float snr;
      for (i=0;i<st->frameSize;i++)
      {
         ener+=st->frame[i]*st->frame[i];
         err += (st->frame[i]-orig[i])*(st->frame[i]-orig[i]);
      }
      snr = 10*log10((ener+1)/(err+1));
      /*printf ("%f %f %f\n", snr, ener, err);*/
   }

   /* Replace input by synthesized speech */
   in[0] = st->frame[0] + st->preemph*st->pre_mem2;
   for (i=1;i<st->frameSize;i++)
     in[i]=st->frame[i] + st->preemph*in[i-1];
   st->pre_mem2=in[st->frameSize-1];

   if (SUBMODE(innovation_quant) == noise_codebook_quant || st->submodeID==0)
      st->bounded_pitch = 1;
   else
      st->bounded_pitch = 0;

   return 1;
}


void *nb_decoder_init(SpeexMode *m)
{
   DecState *st;
   SpeexNBMode *mode;
   int i;

   mode=(SpeexNBMode*)m->mode;
   st = (DecState *)speex_alloc(sizeof(DecState)+4000*sizeof(float));
   st->mode=m;

   st->stack = ((char*)st) + sizeof(DecState);

   st->first=1;
   /* Codec parameters, should eventually have several "modes"*/
   st->frameSize = mode->frameSize;
   st->windowSize = st->frameSize*3/2;
   st->nbSubframes=mode->frameSize/mode->subframeSize;
   st->subframeSize=mode->subframeSize;
   st->lpcSize = mode->lpcSize;
   st->bufSize = mode->bufSize;
   st->gamma1=mode->gamma1;
   st->gamma2=mode->gamma2;
   st->min_pitch=mode->pitchStart;
   st->max_pitch=mode->pitchEnd;
   st->preemph = mode->preemph;

   st->submodes=mode->submodes;
   st->submodeID=mode->defaultSubmode;

   st->pre_mem=0;
   st->lpc_enh_enabled=0;


   st->inBuf = PUSH(st->stack, st->bufSize, float);
   st->frame = st->inBuf + st->bufSize - st->windowSize;
   st->excBuf = PUSH(st->stack, st->bufSize, float);
   st->exc = st->excBuf + st->bufSize - st->windowSize;
   for (i=0;i<st->bufSize;i++)
      st->inBuf[i]=0;
   for (i=0;i<st->bufSize;i++)
      st->excBuf[i]=0;
   st->innov = PUSH(st->stack, st->frameSize, float);

   st->interp_qlpc = PUSH(st->stack, st->lpcSize+1, float);
   st->qlsp = PUSH(st->stack, st->lpcSize, float);
   st->old_qlsp = PUSH(st->stack, st->lpcSize, float);
   st->interp_qlsp = PUSH(st->stack, st->lpcSize, float);