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92ea95e34a
In https://webrtc-review.googlesource.com/c/src/+/1560 we moved WebRTC from src/webrtc to src/ (in order to preserve an healthy git history). This CL takes care of fixing header guards, #include paths, etc... NOPRESUBMIT=true NOTREECHECKS=true NOTRY=true TBR=tommi@webrtc.org Bug: chromium:611808 Change-Id: Iea91618212bee0af16aa3f05071eab8f93706578 Reviewed-on: https://webrtc-review.googlesource.com/1561 Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org> Reviewed-by: Henrik Kjellander <kjellander@webrtc.org> Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org> Cr-Commit-Position: refs/heads/master@{#19846}
87 lines
3.1 KiB
C++
87 lines
3.1 KiB
C++
/*
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* Copyright (c) 2016 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/level_controller/gain_selector.h"
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#include <math.h>
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#include <algorithm>
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#include "modules/audio_processing/include/audio_processing.h"
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#include "modules/audio_processing/level_controller/level_controller_constants.h"
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#include "rtc_base/checks.h"
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namespace webrtc {
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GainSelector::GainSelector() {
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Initialize(AudioProcessing::kSampleRate48kHz);
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}
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void GainSelector::Initialize(int sample_rate_hz) {
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gain_ = 1.f;
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frame_length_ = rtc::CheckedDivExact(sample_rate_hz, 100);
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highly_nonstationary_signal_hold_counter_ = 0;
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}
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// Chooses the gain to apply by the level controller such that
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// 1) The level of the stationary noise does not exceed
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// a predefined threshold.
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// 2) The gain does not exceed the gain that has been found
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// to saturate the signal.
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// 3) The peak level achieves the target peak level.
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// 4) The gain is not below 1.
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// 4) The gain is 1 if the signal has been classified as stationary
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// for a long time.
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// 5) The gain is not above the maximum gain.
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float GainSelector::GetNewGain(float peak_level,
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float noise_energy,
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float saturating_gain,
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bool gain_jumpstart,
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SignalClassifier::SignalType signal_type) {
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RTC_DCHECK_LT(0.f, peak_level);
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if (signal_type == SignalClassifier::SignalType::kHighlyNonStationary ||
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gain_jumpstart) {
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highly_nonstationary_signal_hold_counter_ = 100;
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} else {
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highly_nonstationary_signal_hold_counter_ =
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std::max(0, highly_nonstationary_signal_hold_counter_ - 1);
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}
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float desired_gain;
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if (highly_nonstationary_signal_hold_counter_ > 0) {
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// Compute a desired gain that ensures that the peak level is amplified to
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// the target level.
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desired_gain = kTargetLcPeakLevel / peak_level;
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// Limit the desired gain so that it does not amplify the noise too much.
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float max_noise_energy = kMaxLcNoisePower * frame_length_;
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if (noise_energy * desired_gain * desired_gain > max_noise_energy) {
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RTC_DCHECK_LE(0.f, noise_energy);
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desired_gain = sqrtf(max_noise_energy / noise_energy);
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}
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} else {
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// If the signal has been stationary for a long while, apply a gain of 1 to
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// avoid amplifying pure noise.
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desired_gain = 1.0f;
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}
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// Smootly update the gain towards the desired gain.
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gain_ += 0.2f * (desired_gain - gain_);
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// Limit the gain to not exceed the maximum and the saturating gains, and to
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// ensure that the lowest possible gain is 1.
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gain_ = std::min(gain_, saturating_gain);
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gain_ = std::min(gain_, kMaxLcGain);
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gain_ = std::max(gain_, 1.f);
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return gain_;
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}
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} // namespace webrtc
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