preprocess_spx.c

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   int N, N3, N4, M;

   SpeexPreprocessState *st = (SpeexPreprocessState *)speex_alloc(sizeof(SpeexPreprocessState));
   st->frame_size = frame_size;

   /* Round ps_size down to the nearest power of two */
#if 0
   i=1;
   st->ps_size = st->frame_size;
   while(1)
   {
      if (st->ps_size & ~i)
      {
         st->ps_size &= ~i;
         i<<=1;
      } else {
         break;
      }
   }
   
   
   if (st->ps_size < 3*st->frame_size/4)
      st->ps_size = st->ps_size * 3 / 2;
#else
   st->ps_size = st->frame_size;
#endif

   N = st->ps_size;
   N3 = 2*N - st->frame_size;
   N4 = st->frame_size - N3;
   
   st->sampling_rate = sampling_rate;
   st->denoise_enabled = 1;
   st->agc_enabled = 0;
   st->agc_level = 8000;
   st->vad_enabled = 0;
   st->dereverb_enabled = 0;
   st->reverb_decay = 0;
   st->reverb_level = 0;
   st->noise_suppress = NOISE_SUPPRESS_DEFAULT;
   st->echo_suppress = ECHO_SUPPRESS_DEFAULT;
   st->echo_suppress_active = ECHO_SUPPRESS_ACTIVE_DEFAULT;

   st->speech_prob_start = SPEECH_PROB_START_DEFAULT;
   st->speech_prob_continue = SPEECH_PROB_CONTINUE_DEFAULT;

   st->echo_state = NULL;
   
   st->nbands = NB_BANDS;
   M = st->nbands;
   st->bank = filterbank_new(M, sampling_rate, N, 1);
   
   st->frame = (spx_word16_t*)speex_alloc(2*N*sizeof(spx_word16_t));
   st->window = (spx_word16_t*)speex_alloc(2*N*sizeof(spx_word16_t));
   st->ft = (spx_word16_t*)speex_alloc(2*N*sizeof(spx_word16_t));
   
   st->ps = (spx_word32_t*)speex_alloc((N+M)*sizeof(spx_word32_t));
   st->noise = (spx_word32_t*)speex_alloc((N+M)*sizeof(spx_word32_t));
   st->echo_noise = (spx_word32_t*)speex_alloc((N+M)*sizeof(spx_word32_t));
   st->residual_echo = (spx_word32_t*)speex_alloc((N+M)*sizeof(spx_word32_t));
   st->reverb_estimate = (spx_word32_t*)speex_alloc((N+M)*sizeof(spx_word32_t));
   st->old_ps = (spx_word32_t*)speex_alloc((N+M)*sizeof(spx_word32_t));
   st->prior = (spx_word16_t*)speex_alloc((N+M)*sizeof(spx_word16_t));
   st->post = (spx_word16_t*)speex_alloc((N+M)*sizeof(spx_word16_t));
   st->gain = (spx_word16_t*)speex_alloc((N+M)*sizeof(spx_word16_t));
   st->gain2 = (spx_word16_t*)speex_alloc((N+M)*sizeof(spx_word16_t));
   st->gain_floor = (spx_word16_t*)speex_alloc((N+M)*sizeof(spx_word16_t));
   st->zeta = (spx_word16_t*)speex_alloc((N+M)*sizeof(spx_word16_t));
   
   st->S = (spx_word32_t*)speex_alloc(N*sizeof(spx_word32_t));
   st->Smin = (spx_word32_t*)speex_alloc(N*sizeof(spx_word32_t));
   st->Stmp = (spx_word32_t*)speex_alloc(N*sizeof(spx_word32_t));
   st->update_prob = (int*)speex_alloc(N*sizeof(int));
   
   st->inbuf = (spx_word16_t*)speex_alloc(N3*sizeof(spx_word16_t));
   st->outbuf = (spx_word16_t*)speex_alloc(N3*sizeof(spx_word16_t));

   conj_window(st->window, 2*N3);
   for (i=2*N3;i<2*st->ps_size;i++)
      st->window[i]=Q15_ONE;
   
   if (N4>0)
   {
      for (i=N3-1;i>=0;i--)
      {
         st->window[i+N3+N4]=st->window[i+N3];
         st->window[i+N3]=1;
      }
   }
   for (i=0;i<N+M;i++)
   {
      st->noise[i]=QCONST32(1.f,NOISE_SHIFT);
      st->reverb_estimate[i]=0;
      st->old_ps[i]=1;
      st->gain[i]=Q15_ONE;
      st->post[i]=SHL16(1, SNR_SHIFT);
      st->prior[i]=SHL16(1, SNR_SHIFT);
   }

   for (i=0;i<N;i++)
      st->update_prob[i] = 1;
   for (i=0;i<N3;i++)
   {
      st->inbuf[i]=0;
      st->outbuf[i]=0;
   }
#ifndef FIXED_POINT
   st->loudness_weight = (float*)speex_alloc(N*sizeof(float));
   for (i=0;i<N;i++)
   {
      float ff=((float)i)*.5*sampling_rate/((float)N);
      st->loudness_weight[i] = .35f-.35f*ff/16000.f+.73f*exp(-.5f*(ff-3800)*(ff-3800)/9e5f);
      if (st->loudness_weight[i]<.01f)
         st->loudness_weight[i]=.01f;
      st->loudness_weight[i] *= st->loudness_weight[i];
   }
   st->loudness = pow(6000,LOUDNESS_EXP);
   st->loudness2 = 6000;
   st->nb_loudness_adapt = 0;
#endif
   st->was_speech = 0;

   st->fft_lookup = spx_fft_init(2*N);

   st->nb_adapt=0;
   st->min_count=0;
   return st;
}

void speex_preprocess_state_destroy(SpeexPreprocessState *st)
{
   speex_free(st->frame);
   speex_free(st->ft);
   speex_free(st->ps);
   speex_free(st->gain2);
   speex_free(st->gain_floor);
   speex_free(st->window);
   speex_free(st->noise);
   speex_free(st->reverb_estimate);
   speex_free(st->old_ps);
   speex_free(st->gain);
   speex_free(st->prior);
   speex_free(st->post);
#ifndef FIXED_POINT
   speex_free(st->loudness_weight);
#endif
   speex_free(st->echo_noise);
   speex_free(st->residual_echo);

   speex_free(st->S);
   speex_free(st->Smin);
   speex_free(st->Stmp);
   speex_free(st->update_prob);
   speex_free(st->zeta);

   speex_free(st->inbuf);
   speex_free(st->outbuf);

   spx_fft_destroy(st->fft_lookup);
   filterbank_destroy(st->bank);
   speex_free(st);
}

/* FIXME: The AGC doesn't work yet with fixed-point*/
#ifndef FIXED_POINT
static void speex_compute_agc(SpeexPreprocessState *st)
{
   int i;
   int N = st->ps_size;
   float scale=.5f/N;
   float agc_gain;
   int freq_start, freq_end;
   float active_bands = 0;

   freq_start = (int)(300.0f*2*N/st->sampling_rate);
   freq_end   = (int)(2000.0f*2*N/st->sampling_rate);
   for (i=freq_start;i<freq_end;i++)
   {
      if (st->S[i] > 20.f*st->Smin[i]+1000.f)
         active_bands+=1;
   }
   active_bands /= (freq_end-freq_start+1);

   if (active_bands > .2f)
   {
      float loudness=0.f;
      float rate, rate2=.2f;
      st->nb_loudness_adapt++;
      rate=2.0f/(1+st->nb_loudness_adapt);
      if (rate < .05f)
         rate = .05f;
      if (rate < .1f && pow(loudness, LOUDNESS_EXP) > st->loudness)
         rate = .1f;
      if (rate < .2f && pow(loudness, LOUDNESS_EXP) > 3.f*st->loudness)
         rate = .2f;
      if (rate < .4f && pow(loudness, LOUDNESS_EXP) > 10.f*st->loudness)
         rate = .4f;

      for (i=2;i<N;i++)
      {
         loudness += scale*st->ps[i] * FRAC_SCALING_1*FRAC_SCALING_1*st->gain2[i] * st->gain2[i] * st->loudness_weight[i];
      }
      loudness=sqrt(loudness);
      /*if (loudness < 2*pow(st->loudness, 1.0/LOUDNESS_EXP) &&
        loudness*2 > pow(st->loudness, 1.0/LOUDNESS_EXP))*/
      st->loudness = (1-rate)*st->loudness + (rate)*pow(loudness, LOUDNESS_EXP);
      
      st->loudness2 = (1-rate2)*st->loudness2 + rate2*pow(st->loudness, 1.0f/LOUDNESS_EXP);

      loudness = pow(st->loudness, 1.0f/LOUDNESS_EXP);

      /*fprintf (stderr, "%f %f %f\n", loudness, st->loudness2, rate);*/
   }
   
   agc_gain = st->agc_level/st->loudness2;
   /*fprintf (stderr, "%f %f %f %f\n", active_bands, st->loudness, st->loudness2, agc_gain);*/
   if (agc_gain>200)
      agc_gain = 200;

   for (i=0;i<N;i++)
      st->gain2[i] *= agc_gain;
   
}
#endif

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;
   spx_word32_t *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] = MULT16_16_Q15(st->frame[i], st->window[i]);

#ifdef FIXED_POINT
   {
      spx_word16_t max_val=0;
      for (i=0;i<2*N;i++)
         max_val = MAX16(max_val, ABS16(st->frame[i]));
      st->frame_shift = 14-spx_ilog2(EXTEND32(max_val));
      for (i=0;i<2*N;i++)
         st->frame[i] = SHL16(st->frame[i], st->frame_shift);
   }
#endif
   
   /* Perform FFT */
   spx_fft(st->fft_lookup, st->frame, st->ft);
         
   /* Power spectrum */
   ps[0]=MULT16_16(st->ft[0],st->ft[0]);
   for (i=1;i<N;i++)
      ps[i]=MULT16_16(st->ft[2*i-1],st->ft[2*i-1]) + MULT16_16(st->ft[2*i],st->ft[2*i]);
   for (i=0;i<N;i++)
      st->ps[i] = PSHR32(st->ps[i], 2*st->frame_shift);

   filterbank_compute_bank32(st->bank, ps, ps+N);
}

static void update_noise_prob(SpeexPreprocessState *st)
{
   int i;
   int min_range;
   int N = st->ps_size;

   for (i=1;i<N-1;i++)
      st->S[i] =  MULT16_32_Q15(QCONST16(.8f,15),st->S[i]) + MULT16_32_Q15(QCONST16(.05f,15),st->ps[i-1]) 
                      + MULT16_32_Q15(QCONST16(.1f,15),st->ps[i]) + MULT16_32_Q15(QCONST16(.05f,15),st->ps[i+1]);
   st->S[0] =  MULT16_32_Q15(QCONST16(.8f,15),st->S[0]) + MULT16_32_Q15(QCONST16(.2f,15),st->ps[0]);
   st->S[N-1] =  MULT16_32_Q15(QCONST16(.8f,15),st->S[N-1]) + MULT16_32_Q15(QCONST16(.2f,15),st->ps[N-1]);
   
   if (st->nb_adapt==1)
   {
      for (i=0;i<N;i++)
         st->Smin[i] = st->Stmp[i] = 0;
   }

   if (st->nb_adapt < 100)
      min_range = 15;
   else if (st->nb_adapt < 1000)
      min_range = 50;
   else if (st->nb_adapt < 10000)
      min_range = 150;
   else
      min_range = 300;
   if (st->min_count > min_range)
   {
      st->min_count = 0;
      for (i=0;i<N;i++)
      {
         st->Smin[i] = MIN32(st->Stmp[i], st->S[i]);
         st->Stmp[i] = st->S[i];
      }
   } else {
      for (i=0;i<N;i++)
      {
         st->Smin[i] = MIN32(st->Smin[i], st->S[i]);
         st->Stmp[i] = MIN32(st->Stmp[i], st->S[i]);      
      }
   }
   for (i=0;i<N;i++)
   {
      if (MULT16_32_Q15(QCONST16(.4f,15),st->S[i]) > ADD32(st->Smin[i],EXTEND32(20)))
         st->update_prob[i] = 1;
      else
         st->update_prob[i] = 0;
      /*fprintf (stderr, "%f ", st->S[i]/st->Smin[i]);*/
      /*fprintf (stderr, "%f ", st->update_prob[i]);*/
   }

}

#define NOISE_OVERCOMPENS 1.

void speex_echo_get_residual(SpeexEchoState *st, spx_word32_t *Yout, int len);

int speex_preprocess(SpeexPreprocessState *st, spx_int16_t *x, spx_int32_t *echo)
{
   return speex_preprocess_run(st, x);
}

int speex_preprocess_run(SpeexPreprocessState *st, spx_int16_t *x)
{
   int i;
   int M;
   int N = st->ps_size;
   int N3 = 2*N - st->frame_size;
   int N4 = st->frame_size - N3;
   spx_word32_t *ps=st->ps;
   spx_word32_t Zframe;
   spx_word16_t Pframe;
   spx_word16_t beta, beta_1;
   spx_word16_t effective_echo_suppress;
   
   st->nb_adapt++;
   st->min_count++;
   
   beta = MAX16(QCONST16(.03,15),DIV32_16(Q15_ONE,st->nb_adapt));
   beta_1 = Q15_ONE-beta;
   M = st->nbands;
   /* Deal with residual echo if provided */
   if (st->echo_state)
   {
      speex_echo_get_residual(st->echo_state, st->residual_echo, N);
#ifndef FIXED_POINT
      /* If there are NaNs or ridiculous values, it'll show up in the DC and we just reset everything to zero */
      if (!(st->residual_echo[0] >=0 && st->residual_echo[0]<N*1e9f))
      {
         for (i=0;i<N;i++)
            st->residual_echo[i] = 0;
      }
#endif
      for (i=0;i<N;i++)
         st->echo_noise[i] = MAX32(MULT16_32_Q15(QCONST16(.6f,15),st->echo_noise[i]), st->residual_echo[i]);
      filterbank_compute_bank32(st->bank, st->echo_noise, st->echo_noise+N);
   } else {
      for (i=0;i<N+M;i++)
         st->echo_noise[i] = 0;
   }
   preprocess_analysis(st, x);

   update_noise_prob(st);

   /* Noise estimation always updated for the 10 first frames */
   /*if (st->nb_adapt<10)
   {
      for (i=1;i<N-1;i++)
         st->update_prob[i] = 0;
   }
   */