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/*
Copyright 2018 Google Inc. All Rights Reserved.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS-IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
#include "graph/near_field_effect_node.h"
#include <algorithm>
#include <cmath>
#include "base/logging.h"
#include "base/spherical_angle.h"
#include "dsp/distance_attenuation.h"
#include "dsp/gain.h"
#include "dsp/stereo_panner.h"
namespace vraudio {
NearFieldEffectNode::NearFieldEffectNode(SourceId source_id,
const SystemSettings& system_settings)
: pan_gains_({0.0f, 0.0f}),
near_field_processor_(system_settings.GetSampleRateHz(),
system_settings.GetFramesPerBuffer()),
system_settings_(system_settings),
output_buffer_(kNumStereoChannels, system_settings.GetFramesPerBuffer()) {
output_buffer_.set_source_id(source_id);
}
const AudioBuffer* NearFieldEffectNode::AudioProcess(const NodeInput& input) {
const AudioBuffer* input_buffer = input.GetSingleInput();
DCHECK(input_buffer);
DCHECK_EQ(input_buffer->num_channels(), 1U);
DCHECK_EQ(input_buffer->source_id(), output_buffer_.source_id());
const auto source_parameters =
system_settings_.GetSourceParameters(input_buffer->source_id());
if (source_parameters == nullptr) {
LOG(WARNING) << "Could not find source parameters";
return nullptr;
}
DCHECK_EQ(pan_gains_.size(), kNumStereoChannels);
const float near_field_gain = source_parameters->near_field_gain;
if (near_field_gain > 0.0f) {
const auto& listener_position = system_settings_.GetHeadPosition();
const auto& listener_rotation = system_settings_.GetHeadRotation();
const auto& source_transform = source_parameters->object_transform;
// Compute the relative source direction in spherical angles to calculate
// the left and right panner gains.
WorldPosition relative_direction;
GetRelativeDirection(listener_position, listener_rotation,
source_transform.position, &relative_direction);
const auto source_direction =
SphericalAngle::FromWorldPosition(relative_direction);
CalculateStereoPanGains(source_direction, &pan_gains_);
// Combine pan gains with per-source near field gain.
const float total_near_field_gain =
ComputeNearFieldEffectGain(listener_position,
source_transform.position) *
near_field_gain / kMaxNearFieldEffectGain;
for (size_t i = 0; i < pan_gains_.size(); ++i) {
pan_gains_[i] *= total_near_field_gain;
}
} else {
// Disable near field effect if |near_field_gain| is zero.
std::fill(pan_gains_.begin(), pan_gains_.end(), 0.0f);
}
const float left_current_gain = left_panner_.GetGain();
const float right_current_gain = right_panner_.GetGain();
const float left_target_gain = pan_gains_[0];
const float right_target_gain = pan_gains_[1];
const bool is_left_zero_gain =
IsGainNearZero(left_current_gain) && IsGainNearZero(left_target_gain);
const bool is_right_zero_gain =
IsGainNearZero(right_current_gain) && IsGainNearZero(right_target_gain);
if (is_left_zero_gain && is_right_zero_gain) {
// Make sure gain processors are initialized.
left_panner_.Reset(0.0f);
right_panner_.Reset(0.0f);
// Both channels go to zero, there is no need for further processing.
return nullptr;
}
const auto& input_channel = (*input_buffer)[0];
auto* left_output_channel = &output_buffer_[0];
auto* right_output_channel = &output_buffer_[1];
// Apply bass boost and delay compensation (if necessary) to the input signal
// and place it temporarily in the right output channel. This way we avoid
// allocating a temporary buffer.
near_field_processor_.Process(input_channel, right_output_channel,
source_parameters->enable_hrtf);
left_panner_.ApplyGain(left_target_gain, *right_output_channel,
left_output_channel, /*accumulate_output=*/false);
right_panner_.ApplyGain(right_target_gain, *right_output_channel,
right_output_channel, /*accumulate_output=*/false);
return &output_buffer_;
}
} // namespace vraudio
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