webrtc/modules/audio_coding/codecs/isac/main/source/isac_vad.c

/*
 *  Copyright (c) 2018 The WebRTC project authors. All Rights Reserved.
 *
 *  Use of this source code is governed by a BSD-style license
 *  that can be found in the LICENSE file in the root of the source
 *  tree. An additional intellectual property rights grant can be found
 *  in the file PATENTS.  All contributing project authors may
 *  be found in the AUTHORS file in the root of the source tree.
 */

#include "modules/audio_coding/codecs/isac/main/source/isac_vad.h"

#include <math.h>

void WebRtcIsac_InitPitchFilter(PitchFiltstr* pitchfiltdata) {
  int k;

  for (k = 0; k < PITCH_BUFFSIZE; k++) {
    pitchfiltdata->ubuf[k] = 0.0;
  }
  pitchfiltdata->ystate[0] = 0.0;
  for (k = 1; k < (PITCH_DAMPORDER); k++) {
    pitchfiltdata->ystate[k] = 0.0;
  }
  pitchfiltdata->oldlagp[0] = 50.0;
  pitchfiltdata->oldgainp[0] = 0.0;
}

static void WebRtcIsac_InitWeightingFilter(WeightFiltstr* wfdata) {
  int k;
  double t, dtmp, dtmp2, denum, denum2;

  for (k = 0; k < PITCH_WLPCBUFLEN; k++)
    wfdata->buffer[k] = 0.0;

  for (k = 0; k < PITCH_WLPCORDER; k++) {
    wfdata->istate[k] = 0.0;
    wfdata->weostate[k] = 0.0;
    wfdata->whostate[k] = 0.0;
  }

  /* next part should be in Matlab, writing to a global table */
  t = 0.5;
  denum = 1.0 / ((double)PITCH_WLPCWINLEN);
  denum2 = denum * denum;
  for (k = 0; k < PITCH_WLPCWINLEN; k++) {
    dtmp = PITCH_WLPCASYM * t * denum + (1 - PITCH_WLPCASYM) * t * t * denum2;
    dtmp *= 3.14159265;
    dtmp2 = sin(dtmp);
    wfdata->window[k] = dtmp2 * dtmp2;
    t++;
  }
}

void WebRtcIsac_InitPitchAnalysis(PitchAnalysisStruct* State) {
  int k;

  for (k = 0; k < PITCH_CORR_LEN2 + PITCH_CORR_STEP2 + PITCH_MAX_LAG / 2 -
                      PITCH_FRAME_LEN / 2 + 2;
       k++)
    State->dec_buffer[k] = 0.0;
  for (k = 0; k < 2 * ALLPASSSECTIONS + 1; k++)
    State->decimator_state[k] = 0.0;
  for (k = 0; k < 2; k++)
    State->hp_state[k] = 0.0;
  for (k = 0; k < QLOOKAHEAD; k++)
    State->whitened_buf[k] = 0.0;
  for (k = 0; k < QLOOKAHEAD; k++)
    State->inbuf[k] = 0.0;

  WebRtcIsac_InitPitchFilter(&(State->PFstr_wght));

  WebRtcIsac_InitPitchFilter(&(State->PFstr));

  WebRtcIsac_InitWeightingFilter(&(State->Wghtstr));
}

void WebRtcIsac_InitPreFilterbank(PreFiltBankstr* prefiltdata) {
  int k;

  for (k = 0; k < QLOOKAHEAD; k++) {
    prefiltdata->INLABUF1[k] = 0;
    prefiltdata->INLABUF2[k] = 0;

    prefiltdata->INLABUF1_float[k] = 0;
    prefiltdata->INLABUF2_float[k] = 0;
  }
  for (k = 0; k < 2 * (QORDER - 1); k++) {
    prefiltdata->INSTAT1[k] = 0;
    prefiltdata->INSTAT2[k] = 0;
    prefiltdata->INSTATLA1[k] = 0;
    prefiltdata->INSTATLA2[k] = 0;

    prefiltdata->INSTAT1_float[k] = 0;
    prefiltdata->INSTAT2_float[k] = 0;
    prefiltdata->INSTATLA1_float[k] = 0;
    prefiltdata->INSTATLA2_float[k] = 0;
  }

  /* High pass filter states */
  prefiltdata->HPstates[0] = 0.0;
  prefiltdata->HPstates[1] = 0.0;

  prefiltdata->HPstates_float[0] = 0.0f;
  prefiltdata->HPstates_float[1] = 0.0f;

  return;
}

double WebRtcIsac_LevDurb(double* a, double* k, double* r, size_t order) {
  const double LEVINSON_EPS = 1.0e-10;

  double sum, alpha;
  size_t m, m_h, i;
  alpha = 0;  // warning -DH
  a[0] = 1.0;
  if (r[0] < LEVINSON_EPS) { /* if r[0] <= 0, set LPC coeff. to zero */
    for (i = 0; i < order; i++) {
      k[i] = 0;
      a[i + 1] = 0;
    }
  } else {
    a[1] = k[0] = -r[1] / r[0];
    alpha = r[0] + r[1] * k[0];
    for (m = 1; m < order; m++) {
      sum = r[m + 1];
      for (i = 0; i < m; i++) {
        sum += a[i + 1] * r[m - i];
      }
      k[m] = -sum / alpha;
      alpha += k[m] * sum;
      m_h = (m + 1) >> 1;
      for (i = 0; i < m_h; i++) {
        sum = a[i + 1] + k[m] * a[m - i];
        a[m - i] += k[m] * a[i + 1];
        a[i + 1] = sum;
      }
      a[m + 1] = k[m];
    }
  }
  return alpha;
}

/* The upper channel all-pass filter factors */
const float WebRtcIsac_kUpperApFactorsFloat[2] = {0.03470000000000f,
                                                  0.38260000000000f};

/* The lower channel all-pass filter factors */
const float WebRtcIsac_kLowerApFactorsFloat[2] = {0.15440000000000f,
                                                  0.74400000000000f};

/* This function performs all-pass filtering--a series of first order all-pass
 * sections are used to filter the input in a cascade manner.
 * The input is overwritten!!
 */
void WebRtcIsac_AllPassFilter2Float(float* InOut,
                                    const float* APSectionFactors,
                                    int lengthInOut,
                                    int NumberOfSections,
                                    float* FilterState) {
  int n, j;
  float temp;
  for (j = 0; j < NumberOfSections; j++) {
    for (n = 0; n < lengthInOut; n++) {
      temp = FilterState[j] + APSectionFactors[j] * InOut[n];
      FilterState[j] = -APSectionFactors[j] * temp + InOut[n];
      InOut[n] = temp;
    }
  }
}

/* The number of composite all-pass filter factors */
#define NUMBEROFCOMPOSITEAPSECTIONS 4

/* Function WebRtcIsac_SplitAndFilter
 * This function creates low-pass and high-pass decimated versions of part of
 the input signal, and part of the signal in the input 'lookahead buffer'.

 INPUTS:
 in: a length FRAMESAMPLES array of input samples
 prefiltdata: input data structure containing the filterbank states
 and lookahead samples from the previous encoding
 iteration.
 OUTPUTS:
 LP: a FRAMESAMPLES_HALF array of low-pass filtered samples that
 have been phase equalized.  The first QLOOKAHEAD samples are
 based on the samples in the two prefiltdata->INLABUFx arrays
 each of length QLOOKAHEAD.
 The remaining FRAMESAMPLES_HALF-QLOOKAHEAD samples are based
 on the first FRAMESAMPLES_HALF-QLOOKAHEAD samples of the input
 array in[].
 HP: a FRAMESAMPLES_HALF array of high-pass filtered samples that
 have been phase equalized.  The first QLOOKAHEAD samples are
 based on the samples in the two prefiltdata->INLABUFx arrays
 each of length QLOOKAHEAD.
 The remaining FRAMESAMPLES_HALF-QLOOKAHEAD samples are based
 on the first FRAMESAMPLES_HALF-QLOOKAHEAD samples of the input
 array in[].

 LP_la: a FRAMESAMPLES_HALF array of low-pass filtered samples.
 These samples are not phase equalized. They are computed
 from the samples in the in[] array.
 HP_la: a FRAMESAMPLES_HALF array of high-pass filtered samples
 that are not phase equalized. They are computed from
 the in[] vector.
 prefiltdata: this input data structure's filterbank state and
 lookahead sample buffers are updated for the next
 encoding iteration.
*/
void WebRtcIsac_SplitAndFilterFloat(float* pin,
                                    float* LP,
                                    float* HP,
                                    double* LP_la,
                                    double* HP_la,
                                    PreFiltBankstr* prefiltdata) {
  int k, n;
  float CompositeAPFilterState[NUMBEROFCOMPOSITEAPSECTIONS];
  float ForTransform_CompositeAPFilterState[NUMBEROFCOMPOSITEAPSECTIONS];
  float ForTransform_CompositeAPFilterState2[NUMBEROFCOMPOSITEAPSECTIONS];
  float tempinoutvec[FRAMESAMPLES + MAX_AR_MODEL_ORDER];
  float tempin_ch1[FRAMESAMPLES + MAX_AR_MODEL_ORDER];
  float tempin_ch2[FRAMESAMPLES + MAX_AR_MODEL_ORDER];
  float in[FRAMESAMPLES];
  float ftmp;

  /* HPstcoeff_in = {a1, a2, b1 - b0 * a1, b2 - b0 * a2}; */
  static const float kHpStCoefInFloat[4] = {
      -1.94895953203325f, 0.94984516000000f, -0.05101826139794f,
      0.05015484000000f};

  /* The composite all-pass filter factors */
  static const float WebRtcIsac_kCompositeApFactorsFloat[4] = {
      0.03470000000000f, 0.15440000000000f, 0.38260000000000f,
      0.74400000000000f};

  // The matrix for transforming the backward composite state to upper channel
  // state.
  static const float WebRtcIsac_kTransform1Float[8] = {
      -0.00158678506084f, 0.00127157815343f, -0.00104805672709f,
      0.00084837248079f,  0.00134467983258f, -0.00107756549387f,
      0.00088814793277f,  -0.00071893072525f};

  // The matrix for transforming the backward composite state to lower channel
  // state.
  static const float WebRtcIsac_kTransform2Float[8] = {
      -0.00170686041697f, 0.00136780109829f, -0.00112736532350f,
      0.00091257055385f,  0.00103094281812f, -0.00082615076557f,
      0.00068092756088f,  -0.00055119165484f};

  /* High pass filter */

  for (k = 0; k < FRAMESAMPLES; k++) {
    in[k] = pin[k] + kHpStCoefInFloat[2] * prefiltdata->HPstates_float[0] +
            kHpStCoefInFloat[3] * prefiltdata->HPstates_float[1];
    ftmp = pin[k] - kHpStCoefInFloat[0] * prefiltdata->HPstates_float[0] -
           kHpStCoefInFloat[1] * prefiltdata->HPstates_float[1];
    prefiltdata->HPstates_float[1] = prefiltdata->HPstates_float[0];
    prefiltdata->HPstates_float[0] = ftmp;
  }

  /* First Channel */

  /*initial state of composite filter is zero */
  for (k = 0; k < NUMBEROFCOMPOSITEAPSECTIONS; k++) {
    CompositeAPFilterState[k] = 0.0;
  }
  /* put every other sample of input into a temporary vector in reverse
   * (backward) order*/
  for (k = 0; k < FRAMESAMPLES_HALF; k++) {
    tempinoutvec[k] = in[FRAMESAMPLES - 1 - 2 * k];
  }

  /* now all-pass filter the backwards vector.  Output values overwrite the
   * input vector. */
  WebRtcIsac_AllPassFilter2Float(
      tempinoutvec, WebRtcIsac_kCompositeApFactorsFloat, FRAMESAMPLES_HALF,
      NUMBEROFCOMPOSITEAPSECTIONS, CompositeAPFilterState);

  /* save the backwards filtered output for later forward filtering,
     but write it in forward order*/
  for (k = 0; k < FRAMESAMPLES_HALF; k++) {
    tempin_ch1[FRAMESAMPLES_HALF + QLOOKAHEAD - 1 - k] = tempinoutvec[k];
  }

  /* save the backwards filter state  becaue it will be transformed
     later into a forward state */
  for (k = 0; k < NUMBEROFCOMPOSITEAPSECTIONS; k++) {
    ForTransform_CompositeAPFilterState[k] = CompositeAPFilterState[k];
  }

  /* now backwards filter the samples in the lookahead buffer. The samples were
     placed there in the encoding of the previous frame.  The output samples
     overwrite the input samples */
  WebRtcIsac_AllPassFilter2Float(
      prefiltdata->INLABUF1_float, WebRtcIsac_kCompositeApFactorsFloat,
      QLOOKAHEAD, NUMBEROFCOMPOSITEAPSECTIONS, CompositeAPFilterState);

  /* save the output, but write it in forward order */
  /* write the lookahead samples for the next encoding iteration. Every other
     sample at the end of the input frame is written in reverse order for the
     lookahead length. Exported in the prefiltdata structure. */
  for (k = 0; k < QLOOKAHEAD; k++) {
    tempin_ch1[QLOOKAHEAD - 1 - k] = prefiltdata->INLABUF1_float[k];
    prefiltdata->INLABUF1_float[k] = in[FRAMESAMPLES - 1 - 2 * k];
  }

  /* Second Channel.  This is exactly like the first channel, except that the
     even samples are now filtered instead (lower channel). */
  for (k = 0; k < NUMBEROFCOMPOSITEAPSECTIONS; k++) {
    CompositeAPFilterState[k] = 0.0;
  }

  for (k = 0; k < FRAMESAMPLES_HALF; k++) {
    tempinoutvec[k] = in[FRAMESAMPLES - 2 - 2 * k];
  }

  WebRtcIsac_AllPassFilter2Float(
      tempinoutvec, WebRtcIsac_kCompositeApFactorsFloat, FRAMESAMPLES_HALF,
      NUMBEROFCOMPOSITEAPSECTIONS, CompositeAPFilterState);

  for (k = 0; k < FRAMESAMPLES_HALF; k++) {
    tempin_ch2[FRAMESAMPLES_HALF + QLOOKAHEAD - 1 - k] = tempinoutvec[k];
  }

  for (k = 0; k < NUMBEROFCOMPOSITEAPSECTIONS; k++) {
    ForTransform_CompositeAPFilterState2[k] = CompositeAPFilterState[k];
  }

  WebRtcIsac_AllPassFilter2Float(
      prefiltdata->INLABUF2_float, WebRtcIsac_kCompositeApFactorsFloat,
      QLOOKAHEAD, NUMBEROFCOMPOSITEAPSECTIONS, CompositeAPFilterState);

  for (k = 0; k < QLOOKAHEAD; k++) {
    tempin_ch2[QLOOKAHEAD - 1 - k] = prefiltdata->INLABUF2_float[k];
    prefiltdata->INLABUF2_float[k] = in[FRAMESAMPLES - 2 - 2 * k];
  }

  /* Transform filter states from backward to forward */
  /*At this point, each of the states of the backwards composite filters for the
    two channels are transformed into forward filtering states for the
    corresponding forward channel filters.  Each channel's forward filtering
    state from the previous
    encoding iteration is added to the transformed state to get a proper forward
    state */

  /* So the existing NUMBEROFCOMPOSITEAPSECTIONS x 1 (4x1) state vector is
     multiplied by a NUMBEROFCHANNELAPSECTIONSxNUMBEROFCOMPOSITEAPSECTIONS (2x4)
     transform matrix to get the new state that is added to the previous 2x1
     input state */

  for (k = 0; k < NUMBEROFCHANNELAPSECTIONS; k++) { /* k is row variable */
    for (n = 0; n < NUMBEROFCOMPOSITEAPSECTIONS;
         n++) { /* n is column variable */
      prefiltdata->INSTAT1_float[k] +=
          ForTransform_CompositeAPFilterState[n] *
          WebRtcIsac_kTransform1Float[k * NUMBEROFCHANNELAPSECTIONS + n];
      prefiltdata->INSTAT2_float[k] +=
          ForTransform_CompositeAPFilterState2[n] *
          WebRtcIsac_kTransform2Float[k * NUMBEROFCHANNELAPSECTIONS + n];
    }
  }

  /*obtain polyphase components by forward all-pass filtering through each
   * channel */
  /* the backward filtered samples are now forward filtered with the
   * corresponding channel filters */
  /* The all pass filtering automatically updates the filter states which are
     exported in the prefiltdata structure */
  WebRtcIsac_AllPassFilter2Float(tempin_ch1, WebRtcIsac_kUpperApFactorsFloat,
                                 FRAMESAMPLES_HALF, NUMBEROFCHANNELAPSECTIONS,
                                 prefiltdata->INSTAT1_float);
  WebRtcIsac_AllPassFilter2Float(tempin_ch2, WebRtcIsac_kLowerApFactorsFloat,
                                 FRAMESAMPLES_HALF, NUMBEROFCHANNELAPSECTIONS,
                                 prefiltdata->INSTAT2_float);

  /* Now Construct low-pass and high-pass signals as combinations of polyphase
   * components */
  for (k = 0; k < FRAMESAMPLES_HALF; k++) {
    LP[k] = 0.5f * (tempin_ch1[k] + tempin_ch2[k]); /* low pass signal*/
    HP[k] = 0.5f * (tempin_ch1[k] - tempin_ch2[k]); /* high pass signal*/
  }

  /* Lookahead LP and HP signals */
  /* now create low pass and high pass signals of the input vector.  However, no
     backwards filtering is performed, and hence no phase equalization is
     involved. Also, the input contains some samples that are lookahead samples.
     The high pass and low pass signals that are created are used outside this
     function for analysis (not encoding) purposes */

  /* set up input */
  for (k = 0; k < FRAMESAMPLES_HALF; k++) {
    tempin_ch1[k] = in[2 * k + 1];
    tempin_ch2[k] = in[2 * k];
  }

  /* the input filter states are passed in and updated by the all-pass filtering
     routine and exported in the prefiltdata structure*/
  WebRtcIsac_AllPassFilter2Float(tempin_ch1, WebRtcIsac_kUpperApFactorsFloat,
                                 FRAMESAMPLES_HALF, NUMBEROFCHANNELAPSECTIONS,
                                 prefiltdata->INSTATLA1_float);
  WebRtcIsac_AllPassFilter2Float(tempin_ch2, WebRtcIsac_kLowerApFactorsFloat,
                                 FRAMESAMPLES_HALF, NUMBEROFCHANNELAPSECTIONS,
                                 prefiltdata->INSTATLA2_float);

  for (k = 0; k < FRAMESAMPLES_HALF; k++) {
    LP_la[k] = (float)(0.5f * (tempin_ch1[k] + tempin_ch2[k]));  /*low pass */
    HP_la[k] = (double)(0.5f * (tempin_ch1[k] - tempin_ch2[k])); /* high pass */
  }
}