blob: ca6ec5d4ec1892fbff46dbb3f60ee673b0fb5ceb [file] [log] [blame]
/*
* 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/agc2/adaptive_digital_gain_applier.h"
#include <algorithm>
#include "common_audio/include/audio_util.h"
#include "modules/audio_processing/agc2/agc2_common.h"
#include "modules/audio_processing/logging/apm_data_dumper.h"
#include "rtc_base/numerics/safe_minmax.h"
namespace webrtc {
namespace {
// This function maps input level to desired applied gain. We want to
// boost the signal so that peaks are at -kHeadroomDbfs. We can't
// apply more than kMaxGainDb gain.
float ComputeGainDb(float input_level_dbfs) {
// If the level is very low, boost it as much as we can.
if (input_level_dbfs < -(kHeadroomDbfs + kMaxGainDb)) {
return kMaxGainDb;
}
// We expect to end up here most of the time: the level is below
// -headroom, but we can boost it to -headroom.
if (input_level_dbfs < -kHeadroomDbfs) {
return -kHeadroomDbfs - input_level_dbfs;
}
// Otherwise, the level is too high and we can't boost. The
// LevelEstimator is responsible for not reporting bogus gain
// values.
RTC_DCHECK_LE(input_level_dbfs, 0.f);
return 0.f;
}
// We require 'gain + noise_level <= kMaxNoiseLevelDbfs'.
float LimitGainByNoise(float target_gain,
float input_noise_level_dbfs,
ApmDataDumper* apm_data_dumper) {
const float noise_headroom_db = kMaxNoiseLevelDbfs - input_noise_level_dbfs;
apm_data_dumper->DumpRaw("agc2_noise_headroom_db", noise_headroom_db);
return std::min(target_gain, std::max(noise_headroom_db, 0.f));
}
// Computes how the gain should change during this frame.
// Return the gain difference in db to 'last_gain_db'.
float ComputeGainChangeThisFrameDb(float target_gain_db,
float last_gain_db,
bool gain_increase_allowed) {
float target_gain_difference_db = target_gain_db - last_gain_db;
if (!gain_increase_allowed) {
target_gain_difference_db = std::min(target_gain_difference_db, 0.f);
}
return rtc::SafeClamp(target_gain_difference_db, -kMaxGainChangePerFrameDb,
kMaxGainChangePerFrameDb);
}
} // namespace
AdaptiveDigitalGainApplier::AdaptiveDigitalGainApplier(
ApmDataDumper* apm_data_dumper)
: gain_applier_(false, DbToRatio(last_gain_db_)),
apm_data_dumper_(apm_data_dumper) {}
void AdaptiveDigitalGainApplier::Process(
float input_level_dbfs,
float input_noise_level_dbfs,
const VadWithLevel::LevelAndProbability vad_result,
AudioFrameView<float> float_frame) {
input_level_dbfs = std::min(input_level_dbfs, 0.f);
RTC_DCHECK_GE(input_level_dbfs, -150.f);
RTC_DCHECK_GE(float_frame.num_channels(), 1);
RTC_DCHECK_GE(float_frame.samples_per_channel(), 1);
const float target_gain_db =
LimitGainByNoise(ComputeGainDb(input_level_dbfs), input_noise_level_dbfs,
apm_data_dumper_);
// Forbid increasing the gain when there is no speech.
gain_increase_allowed_ =
vad_result.speech_probability > kVadConfidenceThreshold;
const float gain_change_this_frame_db = ComputeGainChangeThisFrameDb(
target_gain_db, last_gain_db_, gain_increase_allowed_);
apm_data_dumper_->DumpRaw("agc2_want_to_change_by_db",
target_gain_db - last_gain_db_);
apm_data_dumper_->DumpRaw("agc2_will_change_by_db",
gain_change_this_frame_db);
// Optimization: avoid calling math functions if gain does not
// change.
if (gain_change_this_frame_db != 0.f) {
gain_applier_.SetGainFactor(
DbToRatio(last_gain_db_ + gain_change_this_frame_db));
}
gain_applier_.ApplyGain(float_frame);
// Remember that the gain has changed for the next iteration.
last_gain_db_ = last_gain_db_ + gain_change_this_frame_db;
apm_data_dumper_->DumpRaw("agc2_applied_gain_db", last_gain_db_);
}
} // namespace webrtc