1/*
2Copyright 2018 Google Inc. All Rights Reserved.
3
4Licensed under the Apache License, Version 2.0 (the "License");
5you may not use this file except in compliance with the License.
6You may obtain a copy of the License at
7
8 http://www.apache.org/licenses/LICENSE-2.0
9
10Unless required by applicable law or agreed to in writing, software
11distributed under the License is distributed on an "AS-IS" BASIS,
12WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13See the License for the specific language governing permissions and
14limitations under the License.
15*/
16
17#include "graph/near_field_effect_node.h"
18
19#include <algorithm>
20#include <cmath>
21
22#include "base/logging.h"
23#include "base/spherical_angle.h"
24
25#include "dsp/distance_attenuation.h"
26#include "dsp/gain.h"
27#include "dsp/stereo_panner.h"
28
29namespace vraudio {
30
31NearFieldEffectNode::NearFieldEffectNode(SourceId source_id,
32 const SystemSettings& system_settings)
33 : pan_gains_({0.0f, 0.0f}),
34 near_field_processor_(system_settings.GetSampleRateHz(),
35 system_settings.GetFramesPerBuffer()),
36 system_settings_(system_settings),
37 output_buffer_(kNumStereoChannels, system_settings.GetFramesPerBuffer()) {
38 output_buffer_.set_source_id(source_id);
39}
40
41const AudioBuffer* NearFieldEffectNode::AudioProcess(const NodeInput& input) {
42
43
44 const AudioBuffer* input_buffer = input.GetSingleInput();
45 DCHECK(input_buffer);
46 DCHECK_EQ(input_buffer->num_channels(), 1U);
47 DCHECK_EQ(input_buffer->source_id(), output_buffer_.source_id());
48
49 const auto source_parameters =
50 system_settings_.GetSourceParameters(source_id: input_buffer->source_id());
51 if (source_parameters == nullptr) {
52 LOG(WARNING) << "Could not find source parameters";
53 return nullptr;
54 }
55
56
57 DCHECK_EQ(pan_gains_.size(), kNumStereoChannels);
58 const float near_field_gain = source_parameters->near_field_gain;
59 if (near_field_gain > 0.0f) {
60 const auto& listener_position = system_settings_.GetHeadPosition();
61 const auto& listener_rotation = system_settings_.GetHeadRotation();
62 const auto& source_transform = source_parameters->object_transform;
63 // Compute the relative source direction in spherical angles to calculate
64 // the left and right panner gains.
65 WorldPosition relative_direction;
66 GetRelativeDirection(from_position: listener_position, from_rotation: listener_rotation,
67 to_position: source_transform.position, relative_direction: &relative_direction);
68 const auto source_direction =
69 SphericalAngle::FromWorldPosition(world_position: relative_direction);
70 CalculateStereoPanGains(source_direction, stereo_gains: &pan_gains_);
71 // Combine pan gains with per-source near field gain.
72 const float total_near_field_gain =
73 ComputeNearFieldEffectGain(listener_position,
74 source_position: source_transform.position) *
75 near_field_gain / kMaxNearFieldEffectGain;
76 for (size_t i = 0; i < pan_gains_.size(); ++i) {
77 pan_gains_[i] *= total_near_field_gain;
78 }
79 } else {
80 // Disable near field effect if |near_field_gain| is zero.
81 std::fill(first: pan_gains_.begin(), last: pan_gains_.end(), value: 0.0f);
82 }
83
84 const float left_current_gain = left_panner_.GetGain();
85 const float right_current_gain = right_panner_.GetGain();
86 const float left_target_gain = pan_gains_[0];
87 const float right_target_gain = pan_gains_[1];
88 const bool is_left_zero_gain =
89 IsGainNearZero(gain: left_current_gain) && IsGainNearZero(gain: left_target_gain);
90 const bool is_right_zero_gain =
91 IsGainNearZero(gain: right_current_gain) && IsGainNearZero(gain: right_target_gain);
92
93 if (is_left_zero_gain && is_right_zero_gain) {
94 // Make sure gain processors are initialized.
95 left_panner_.Reset(gain: 0.0f);
96 right_panner_.Reset(gain: 0.0f);
97 // Both channels go to zero, there is no need for further processing.
98 return nullptr;
99 }
100
101 const auto& input_channel = (*input_buffer)[0];
102 auto* left_output_channel = &output_buffer_[0];
103 auto* right_output_channel = &output_buffer_[1];
104 // Apply bass boost and delay compensation (if necessary) to the input signal
105 // and place it temporarily in the right output channel. This way we avoid
106 // allocating a temporary buffer.
107 near_field_processor_.Process(input: input_channel, output: right_output_channel,
108 enable_hrtf: source_parameters->enable_hrtf);
109 left_panner_.ApplyGain(target_gain: left_target_gain, input: *right_output_channel,
110 output: left_output_channel, /*accumulate_output=*/false);
111 right_panner_.ApplyGain(target_gain: right_target_gain, input: *right_output_channel,
112 output: right_output_channel, /*accumulate_output=*/false);
113
114 return &output_buffer_;
115}
116
117} // namespace vraudio
118

source code of qtmultimedia/src/3rdparty/resonance-audio/resonance_audio/graph/near_field_effect_node.cc