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/*
* Copyright (c) 2018 The WebRTC project authors. All Rights Reserved.
*
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE file in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
*/
#include "modules/audio_processing/aec3/echo_audibility.h"
#include <algorithm>
#include <cmath>
#include <utility>
#include <vector>
#include "api/array_view.h"
#include "modules/audio_processing/aec3/block_buffer.h"
#include "modules/audio_processing/aec3/spectrum_buffer.h"
#include "modules/audio_processing/aec3/stationarity_estimator.h"
namespace webrtc {
EchoAudibility::EchoAudibility(bool use_render_stationarity_at_init)
: use_render_stationarity_at_init_(use_render_stationarity_at_init) {
Reset();
}
EchoAudibility::~EchoAudibility() = default;
void EchoAudibility::Update(const RenderBuffer& render_buffer,
rtc::ArrayView<const float> average_reverb,
int delay_blocks,
bool external_delay_seen) {
UpdateRenderNoiseEstimator(render_buffer.GetSpectrumBuffer(),
render_buffer.GetBlockBuffer(),
external_delay_seen);
if (external_delay_seen || use_render_stationarity_at_init_) {
UpdateRenderStationarityFlags(render_buffer, average_reverb, delay_blocks);
}
}
void EchoAudibility::Reset() {
render_stationarity_.Reset();
non_zero_render_seen_ = false;
render_spectrum_write_prev_ = absl::nullopt;
}
void EchoAudibility::UpdateRenderStationarityFlags(
const RenderBuffer& render_buffer,
rtc::ArrayView<const float> average_reverb,
int min_channel_delay_blocks) {
const SpectrumBuffer& spectrum_buffer = render_buffer.GetSpectrumBuffer();
int idx_at_delay = spectrum_buffer.OffsetIndex(spectrum_buffer.read,
min_channel_delay_blocks);
int num_lookahead = render_buffer.Headroom() - min_channel_delay_blocks + 1;
num_lookahead = std::max(0, num_lookahead);
render_stationarity_.UpdateStationarityFlags(spectrum_buffer, average_reverb,
idx_at_delay, num_lookahead);
}
void EchoAudibility::UpdateRenderNoiseEstimator(
const SpectrumBuffer& spectrum_buffer,
const BlockBuffer& block_buffer,
bool external_delay_seen) {
if (!render_spectrum_write_prev_) {
render_spectrum_write_prev_ = spectrum_buffer.write;
render_block_write_prev_ = block_buffer.write;
return;
}
int render_spectrum_write_current = spectrum_buffer.write;
if (!non_zero_render_seen_ && !external_delay_seen) {
non_zero_render_seen_ = !IsRenderTooLow(block_buffer);
}
if (non_zero_render_seen_) {
for (int idx = render_spectrum_write_prev_.value();
idx != render_spectrum_write_current;
idx = spectrum_buffer.DecIndex(idx)) {
render_stationarity_.UpdateNoiseEstimator(spectrum_buffer.buffer[idx]);
}
}
render_spectrum_write_prev_ = render_spectrum_write_current;
}
bool EchoAudibility::IsRenderTooLow(const BlockBuffer& block_buffer) {
const int num_render_channels =
static_cast<int>(block_buffer.buffer[0].NumChannels());
bool too_low = false;
const int render_block_write_current = block_buffer.write;
if (render_block_write_current == render_block_write_prev_) {
too_low = true;
} else {
for (int idx = render_block_write_prev_; idx != render_block_write_current;
idx = block_buffer.IncIndex(idx)) {
float max_abs_over_channels = 0.f;
for (int ch = 0; ch < num_render_channels; ++ch) {
rtc::ArrayView<const float, kBlockSize> block =
block_buffer.buffer[idx].View(/*band=*/0, /*channel=*/ch);
auto r = std::minmax_element(block.cbegin(), block.cend());
float max_abs_channel =
std::max(std::fabs(*r.first), std::fabs(*r.second));
max_abs_over_channels =
std::max(max_abs_over_channels, max_abs_channel);
}
if (max_abs_over_channels < 10.f) {
too_low = true; // Discards all blocks if one of them is too low.
break;
}
}
}
render_block_write_prev_ = render_block_write_current;
return too_low;
}
} // namespace webrtc