Line data    Source code

       1             : /*
       2             :  *  Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
       3             :  *
       4             :  *  Use of this source code is governed by a BSD-style license
       5             :  *  that can be found in the LICENSE file in the root of the source
       6             :  *  tree. An additional intellectual property rights grant can be found
       7             :  *  in the file PATENTS.  All contributing project authors may
       8             :  *  be found in the AUTHORS file in the root of the source tree.
       9             :  */
      10             : #include "webrtc/modules/audio_processing/aec3/cascaded_biquad_filter.h"
      11             : 
      12             : #include "webrtc/base/checks.h"
      13             : 
      14             : namespace webrtc {
      15             : 
      16           0 : CascadedBiQuadFilter::CascadedBiQuadFilter(
      17             :     const CascadedBiQuadFilter::BiQuadCoefficients& coefficients,
      18           0 :     size_t num_biquads)
      19           0 :     : biquad_states_(num_biquads), coefficients_(coefficients) {}
      20             : 
      21             : CascadedBiQuadFilter::~CascadedBiQuadFilter() = default;
      22             : 
      23           0 : void CascadedBiQuadFilter::Process(rtc::ArrayView<const float> x,
      24             :                                    rtc::ArrayView<float> y) {
      25           0 :   ApplyBiQuad(x, y, &biquad_states_[0]);
      26           0 :   for (size_t k = 1; k < biquad_states_.size(); ++k) {
      27           0 :     ApplyBiQuad(y, y, &biquad_states_[k]);
      28             :   }
      29           0 : }
      30             : 
      31           0 : void CascadedBiQuadFilter::Process(rtc::ArrayView<float> y) {
      32           0 :   for (auto& biquad : biquad_states_) {
      33           0 :     ApplyBiQuad(y, y, &biquad);
      34             :   }
      35           0 : }
      36             : 
      37           0 : void CascadedBiQuadFilter::ApplyBiQuad(
      38             :     rtc::ArrayView<const float> x,
      39             :     rtc::ArrayView<float> y,
      40             :     CascadedBiQuadFilter::BiQuadState* biquad_state) {
      41           0 :   RTC_DCHECK_EQ(x.size(), y.size());
      42           0 :   RTC_DCHECK(biquad_state);
      43           0 :   const auto c_b = coefficients_.b;
      44           0 :   const auto c_a = coefficients_.a;
      45           0 :   auto m_x = biquad_state->x;
      46           0 :   auto m_y = biquad_state->y;
      47           0 :   for (size_t k = 0; k < x.size(); ++k) {
      48           0 :     const float tmp = x[k];
      49           0 :     y[k] = c_b[0] * tmp + c_b[1] * m_x[0] + c_b[2] * m_x[1] - c_a[0] * m_y[0] -
      50           0 :            c_a[1] * m_y[1];
      51           0 :     m_x[1] = m_x[0];
      52           0 :     m_x[0] = tmp;
      53           0 :     m_y[1] = m_y[0];
      54           0 :     m_y[0] = y[k];
      55             :   }
      56           0 : }
      57             : 
      58             : }  // namespace webrtc