109 lines
3.4 KiB
C++
109 lines
3.4 KiB
C++
/*
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* Copyright (c) 2018 The WebRTC project authors. All Rights Reserved.
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*
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* Use of this source code is governed by a BSD-style license
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* that can be found in the LICENSE file in the root of the source
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* tree. An additional intellectual property rights grant can be found
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* in the file PATENTS. All contributing project authors may
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* be found in the AUTHORS file in the root of the source tree.
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*/
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#include "modules/audio_processing/aec3/reverb_frequency_response.h"
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#include <stddef.h>
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#include <algorithm>
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#include <array>
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#include <numeric>
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#include "api/array_view.h"
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#include "modules/audio_processing/aec3/aec3_common.h"
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#include "rtc_base/checks.h"
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namespace webrtc {
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namespace {
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// Computes the ratio of the energies between the direct path and the tail. The
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// energy is computed in the power spectrum domain discarding the DC
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// contributions.
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float AverageDecayWithinFilter(
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rtc::ArrayView<const float> freq_resp_direct_path,
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rtc::ArrayView<const float> freq_resp_tail) {
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// Skipping the DC for the ratio computation
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constexpr size_t kSkipBins = 1;
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RTC_CHECK_EQ(freq_resp_direct_path.size(), freq_resp_tail.size());
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float direct_path_energy =
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std::accumulate(freq_resp_direct_path.begin() + kSkipBins,
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freq_resp_direct_path.end(), 0.f);
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if (direct_path_energy == 0.f) {
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return 0.f;
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}
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float tail_energy = std::accumulate(freq_resp_tail.begin() + kSkipBins,
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freq_resp_tail.end(), 0.f);
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return tail_energy / direct_path_energy;
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}
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} // namespace
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ReverbFrequencyResponse::ReverbFrequencyResponse(
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bool use_conservative_tail_frequency_response)
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: use_conservative_tail_frequency_response_(
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use_conservative_tail_frequency_response) {
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tail_response_.fill(0.0f);
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}
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ReverbFrequencyResponse::~ReverbFrequencyResponse() = default;
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void ReverbFrequencyResponse::Update(
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const std::vector<std::array<float, kFftLengthBy2Plus1>>&
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frequency_response,
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int filter_delay_blocks,
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const absl::optional<float>& linear_filter_quality,
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bool stationary_block) {
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if (stationary_block || !linear_filter_quality) {
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return;
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}
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Update(frequency_response, filter_delay_blocks, *linear_filter_quality);
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}
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void ReverbFrequencyResponse::Update(
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const std::vector<std::array<float, kFftLengthBy2Plus1>>&
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frequency_response,
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int filter_delay_blocks,
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float linear_filter_quality) {
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rtc::ArrayView<const float> freq_resp_tail(
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frequency_response[frequency_response.size() - 1]);
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rtc::ArrayView<const float> freq_resp_direct_path(
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frequency_response[filter_delay_blocks]);
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float average_decay =
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AverageDecayWithinFilter(freq_resp_direct_path, freq_resp_tail);
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const float smoothing = 0.2f * linear_filter_quality;
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average_decay_ += smoothing * (average_decay - average_decay_);
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for (size_t k = 0; k < kFftLengthBy2Plus1; ++k) {
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tail_response_[k] = freq_resp_direct_path[k] * average_decay_;
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}
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if (use_conservative_tail_frequency_response_) {
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for (size_t k = 0; k < kFftLengthBy2Plus1; ++k) {
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tail_response_[k] = std::max(freq_resp_tail[k], tail_response_[k]);
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}
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}
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for (size_t k = 1; k < kFftLengthBy2; ++k) {
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const float avg_neighbour =
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0.5f * (tail_response_[k - 1] + tail_response_[k + 1]);
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tail_response_[k] = std::max(tail_response_[k], avg_neighbour);
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}
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}
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} // namespace webrtc
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