reverb_frequency_response.cc (3474B)
1 /* 2 * Copyright (c) 2018 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/aec3/reverb_frequency_response.h" 12 13 #include <algorithm> 14 #include <array> 15 #include <cstddef> 16 #include <numeric> 17 #include <optional> 18 #include <vector> 19 20 #include "api/array_view.h" 21 #include "modules/audio_processing/aec3/aec3_common.h" 22 #include "rtc_base/checks.h" 23 24 namespace webrtc { 25 26 namespace { 27 28 // Computes the ratio of the energies between the direct path and the tail. The 29 // energy is computed in the power spectrum domain discarding the DC 30 // contributions. 31 float AverageDecayWithinFilter(ArrayView<const float> freq_resp_direct_path, 32 ArrayView<const float> freq_resp_tail) { 33 // Skipping the DC for the ratio computation 34 constexpr size_t kSkipBins = 1; 35 RTC_CHECK_EQ(freq_resp_direct_path.size(), freq_resp_tail.size()); 36 37 float direct_path_energy = 38 std::accumulate(freq_resp_direct_path.begin() + kSkipBins, 39 freq_resp_direct_path.end(), 0.f); 40 41 if (direct_path_energy == 0.f) { 42 return 0.f; 43 } 44 45 float tail_energy = std::accumulate(freq_resp_tail.begin() + kSkipBins, 46 freq_resp_tail.end(), 0.f); 47 return tail_energy / direct_path_energy; 48 } 49 50 } // namespace 51 52 ReverbFrequencyResponse::ReverbFrequencyResponse( 53 bool use_conservative_tail_frequency_response) 54 : use_conservative_tail_frequency_response_( 55 use_conservative_tail_frequency_response) { 56 tail_response_.fill(0.0f); 57 } 58 59 ReverbFrequencyResponse::~ReverbFrequencyResponse() = default; 60 61 void ReverbFrequencyResponse::Update( 62 const std::vector<std::array<float, kFftLengthBy2Plus1>>& 63 frequency_response, 64 int filter_delay_blocks, 65 const std::optional<float>& linear_filter_quality, 66 bool stationary_block) { 67 if (stationary_block || !linear_filter_quality) { 68 return; 69 } 70 71 Update(frequency_response, filter_delay_blocks, *linear_filter_quality); 72 } 73 74 void ReverbFrequencyResponse::Update( 75 const std::vector<std::array<float, kFftLengthBy2Plus1>>& 76 frequency_response, 77 int filter_delay_blocks, 78 float linear_filter_quality) { 79 ArrayView<const float> freq_resp_tail( 80 frequency_response[frequency_response.size() - 1]); 81 82 ArrayView<const float> freq_resp_direct_path( 83 frequency_response[filter_delay_blocks]); 84 85 float average_decay = 86 AverageDecayWithinFilter(freq_resp_direct_path, freq_resp_tail); 87 88 const float smoothing = 0.2f * linear_filter_quality; 89 average_decay_ += smoothing * (average_decay - average_decay_); 90 91 for (size_t k = 0; k < kFftLengthBy2Plus1; ++k) { 92 tail_response_[k] = freq_resp_direct_path[k] * average_decay_; 93 } 94 95 if (use_conservative_tail_frequency_response_) { 96 for (size_t k = 0; k < kFftLengthBy2Plus1; ++k) { 97 tail_response_[k] = std::max(freq_resp_tail[k], tail_response_[k]); 98 } 99 } 100 101 for (size_t k = 1; k < kFftLengthBy2; ++k) { 102 const float avg_neighbour = 103 0.5f * (tail_response_[k - 1] + tail_response_[k + 1]); 104 tail_response_[k] = std::max(tail_response_[k], avg_neighbour); 105 } 106 } 107 108 } // namespace webrtc