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 11 #include "modules/audio_processing/agc2/biquad_filter.h" 12 13 #include "rtc_base/arraysize.h" 14 15 namespace webrtc { 16 BiQuadFilter(const Config & config)17BiQuadFilter::BiQuadFilter(const Config& config) 18 : config_(config), state_({}) {} 19 20 BiQuadFilter::~BiQuadFilter() = default; 21 SetConfig(const Config & config)22void BiQuadFilter::SetConfig(const Config& config) { 23 config_ = config; 24 state_ = {}; 25 } 26 Reset()27void BiQuadFilter::Reset() { 28 state_ = {}; 29 } 30 Process(rtc::ArrayView<const float> x,rtc::ArrayView<float> y)31void BiQuadFilter::Process(rtc::ArrayView<const float> x, 32 rtc::ArrayView<float> y) { 33 RTC_DCHECK_EQ(x.size(), y.size()); 34 const float config_a0 = config_.a[0]; 35 const float config_a1 = config_.a[1]; 36 const float config_b0 = config_.b[0]; 37 const float config_b1 = config_.b[1]; 38 const float config_b2 = config_.b[2]; 39 float state_a0 = state_.a[0]; 40 float state_a1 = state_.a[1]; 41 float state_b0 = state_.b[0]; 42 float state_b1 = state_.b[1]; 43 for (size_t k = 0, x_size = x.size(); k < x_size; ++k) { 44 // Use a temporary variable for `x[k]` to allow in-place processing. 45 const float tmp = x[k]; 46 float y_k = config_b0 * tmp + config_b1 * state_b0 + config_b2 * state_b1 - 47 config_a0 * state_a0 - config_a1 * state_a1; 48 state_b1 = state_b0; 49 state_b0 = tmp; 50 state_a1 = state_a0; 51 state_a0 = y_k; 52 y[k] = y_k; 53 } 54 state_.a[0] = state_a0; 55 state_.a[1] = state_a1; 56 state_.b[0] = state_b0; 57 state_.b[1] = state_b1; 58 } 59 60 } // namespace webrtc 61