1 /*
2 * Copyright (c) 2023, Alliance for Open Media. All rights reserved
3 *
4 * This source code is subject to the terms of the BSD 3-Clause Clear License
5 * and the Alliance for Open Media Patent License 1.0. If the BSD 3-Clause Clear
6 * License was not distributed with this source code in the LICENSE file, you
7 * can obtain it at www.aomedia.org/license/software-license/bsd-3-c-c. If the
8 * Alliance for Open Media Patent License 1.0 was not distributed with this
9 * source code in the PATENTS file, you can obtain it at
10 * www.aomedia.org/license/patent.
11 */
12 #include "iamf/cli/recon_gain_generator.h"
13
14 #include <cmath>
15 #include <vector>
16
17 #include "absl/base/no_destructor.h"
18 #include "absl/container/flat_hash_map.h"
19 #include "absl/log/log.h"
20 #include "absl/status/status.h"
21 #include "iamf/cli/channel_label.h"
22 #include "iamf/cli/demixing_module.h"
23 #include "iamf/common/utils/macros.h"
24 #include "iamf/common/utils/map_utils.h"
25 #include "iamf/obu/types.h"
26
27 namespace iamf_tools {
28
29 namespace {
30
31 // Returns the Root Mean Square (RMS) power of input `samples`.
ComputeSignalPower(const std::vector<InternalSampleType> & samples)32 double ComputeSignalPower(const std::vector<InternalSampleType>& samples) {
33 double mean_square = 0.0;
34 const double scale = 1.0 / static_cast<double>(samples.size());
35 for (const auto s : samples) {
36 mean_square += scale * s * s;
37 }
38 return std::sqrt(mean_square);
39 }
40
41 // Find relevant samples. E.g. Computation of kDemixedLrs7 uses kLs5 and kLss7.
42 // Spec says "relevant mixed channel of the down-mixed audio for CL #i-1." So
43 // Level Mk is the signal power or kLs5. kLss7 is from CL #i and does not
44 // contribute to Level Mk.
FindRelevantMixedSamples(const bool additional_logging,ChannelLabel::Label label,const LabelSamplesMap & label_to_samples,const std::vector<InternalSampleType> ** relevant_mixed_samples)45 absl::Status FindRelevantMixedSamples(
46 const bool additional_logging, ChannelLabel::Label label,
47 const LabelSamplesMap& label_to_samples,
48 const std::vector<InternalSampleType>** relevant_mixed_samples) {
49 using enum ChannelLabel::Label;
50 static const absl::NoDestructor<
51 absl::flat_hash_map<ChannelLabel::Label, ChannelLabel::Label>>
52 kLabelToRelevantMixedLabel({{kDemixedL7, kL5},
53 {kDemixedR7, kR5},
54 {kDemixedLrs7, kLs5},
55 {kDemixedRrs7, kRs5},
56 {kDemixedLtb4, kLtf2},
57 {kDemixedRtb4, kRtf2},
58 {kDemixedL5, kL3},
59 {kDemixedR5, kR3},
60 {kDemixedLs5, kL3},
61 {kDemixedRs5, kR3},
62 {kDemixedLtf2, kLtf3},
63 {kDemixedRtf2, kRtf3},
64 {kDemixedL3, kL2},
65 {kDemixedR3, kR2},
66 {kDemixedR2, kMono}});
67
68 ChannelLabel::Label relevant_mixed_label;
69 RETURN_IF_NOT_OK(
70 CopyFromMap(*kLabelToRelevantMixedLabel, label,
71 "`relevant_mixed_label` for demixed `ChannelLabel::Label`",
72 relevant_mixed_label));
73
74 LOG_IF(INFO, additional_logging)
75 << "Relevant mixed samples has label: " << relevant_mixed_label;
76 return DemixingModule::FindSamplesOrDemixedSamples(
77 relevant_mixed_label, label_to_samples, relevant_mixed_samples);
78 }
79
80 } // namespace
81
ComputeReconGain(ChannelLabel::Label label,const LabelSamplesMap & label_to_samples,const LabelSamplesMap & label_to_decoded_samples,const bool additional_logging,double & recon_gain)82 absl::Status ReconGainGenerator::ComputeReconGain(
83 ChannelLabel::Label label, const LabelSamplesMap& label_to_samples,
84 const LabelSamplesMap& label_to_decoded_samples,
85 const bool additional_logging, double& recon_gain) {
86 // Gather information about the original samples.
87 const std::vector<InternalSampleType>* original_samples;
88 RETURN_IF_NOT_OK(DemixingModule::FindSamplesOrDemixedSamples(
89 label, label_to_samples, &original_samples));
90 LOG_IF(INFO, additional_logging)
91 << "[" << label
92 << "] original_samples.size()= " << original_samples->size();
93
94 // Level Ok in the Spec.
95 const double original_power = ComputeSignalPower(*original_samples);
96
97 // TODO(b/289064747): Investigate if the recon gain mismatches are resolved
98 // after we switched to representing data in [-1, +1].
99 // If 10*log10(level Ok / maxL^2) is less than the first threshold value
100 // (e.g. -80dB), Recon_Gain (k, i) = 0. Where, maxL = 32767 for 16bits.
101 // In this codebase we represent the `InternalSampleType` as a `double` in the
102 // range of [-1, +1], so we use maxL = 1.0 instead.
103 constexpr InternalSampleType kMaxLSquared = 1.0 * 1.0;
104 const double original_power_db = 10 * log10(original_power / kMaxLSquared);
105 LOG_IF(INFO, additional_logging) << "Level OK (dB) " << original_power_db;
106 if (original_power_db < -80) {
107 recon_gain = 0;
108 return absl::OkStatus();
109 }
110
111 // Gather information about mixed samples.
112 const std::vector<InternalSampleType>* relevant_mixed_samples;
113 RETURN_IF_NOT_OK(FindRelevantMixedSamples(
114 additional_logging, label, label_to_samples, &relevant_mixed_samples));
115 LOG_IF(INFO, additional_logging)
116 << "[" << label
117 << "] relevant_mixed_samples.size()= " << relevant_mixed_samples->size();
118
119 // Level Mk in the Spec.
120 const double relevant_mixed_power =
121 ComputeSignalPower(*relevant_mixed_samples);
122 const double mixed_power_db = 10 * log10(relevant_mixed_power / kMaxLSquared);
123 LOG_IF(INFO, additional_logging) << "Level MK (dB) " << mixed_power_db;
124
125 // If 10*log10(level Ok / level Mk ) is less than the second threshold
126 // value (e.g. -6dB), Recon_Gain (k, i) is set to the value which makes
127 // level Ok = Recon_Gain (k, i)^2 x level Dk.
128 double original_mixed_ratio_db =
129 10 * log10(original_power / relevant_mixed_power);
130 LOG_IF(INFO, additional_logging)
131 << "Level Ok (dB) / Level Mk (dB) " << original_mixed_ratio_db;
132
133 // Otherwise, Recon_Gain (k, i) = 1.
134 if (original_mixed_ratio_db >= -6) {
135 recon_gain = 1;
136 return absl::OkStatus();
137 }
138
139 // Gather information about the demixed samples.
140 const std::vector<InternalSampleType>* demixed_samples;
141 RETURN_IF_NOT_OK(DemixingModule::FindSamplesOrDemixedSamples(
142 label, label_to_decoded_samples, &demixed_samples));
143 LOG_IF(INFO, additional_logging)
144 << "[" << label
145 << "] demixed_samples.size()= " << demixed_samples->size();
146
147 // Level Dk in the Spec.
148 const double demixed_power = ComputeSignalPower(*demixed_samples);
149
150 // Set recon gain to the value implied by the spec.
151 double demixed_power_ratio_db = 10 * log10(demixed_power / mixed_power_db);
152 LOG_IF(INFO, additional_logging)
153 << "Level DK (dB) " << demixed_power_ratio_db;
154 recon_gain = std::sqrt(original_power / demixed_power);
155
156 return absl::OkStatus();
157 }
158
159 } // namespace iamf_tools
160