1 /*
2 * Copyright (c) 2018 The WebRTC project authors. All Rights Reserved.
3 *
4 * Use of this source code is governed by a BSD-style license
5 * that can be found in the LICENSE file in the root of the source
6 * tree. An additional intellectual property rights grant can be found
7 * in the file PATENTS. All contributing project authors may
8 * be found in the AUTHORS file in the root of the source tree.
9 */
10
11 #include "modules/audio_processing/agc2/fixed_gain_controller.h"
12
13 #include "api/array_view.h"
14 #include "common_audio/include/audio_util.h"
15 #include "modules/audio_processing/agc2/agc2_common.h"
16 #include "modules/audio_processing/logging/apm_data_dumper.h"
17 #include "rtc_base/checks.h"
18 #include "rtc_base/logging.h"
19 #include "rtc_base/numerics/safe_minmax.h"
20
21 namespace webrtc {
22 namespace {
23
24 // Returns true when the gain factor is so close to 1 that it would
25 // not affect int16 samples.
CloseToOne(float gain_factor)26 bool CloseToOne(float gain_factor) {
27 return 1.f - 1.f / kMaxFloatS16Value <= gain_factor &&
28 gain_factor <= 1.f + 1.f / kMaxFloatS16Value;
29 }
30 } // namespace
31
FixedGainController(ApmDataDumper * apm_data_dumper)32 FixedGainController::FixedGainController(ApmDataDumper* apm_data_dumper)
33 : FixedGainController(apm_data_dumper, "Agc2") {}
34
FixedGainController(ApmDataDumper * apm_data_dumper,std::string histogram_name_prefix)35 FixedGainController::FixedGainController(ApmDataDumper* apm_data_dumper,
36 std::string histogram_name_prefix)
37 : apm_data_dumper_(apm_data_dumper),
38 limiter_(48000, apm_data_dumper_, histogram_name_prefix) {
39 // Do update histograms.xml when adding name prefixes.
40 RTC_DCHECK(histogram_name_prefix == "" || histogram_name_prefix == "Test" ||
41 histogram_name_prefix == "AudioMixer" ||
42 histogram_name_prefix == "Agc2");
43 }
44
SetGain(float gain_to_apply_db)45 void FixedGainController::SetGain(float gain_to_apply_db) {
46 // Changes in gain_to_apply_ cause discontinuities. We assume
47 // gain_to_apply_ is set in the beginning of the call. If it is
48 // frequently changed, we should add interpolation between the
49 // values.
50 // The gain
51 RTC_DCHECK_LE(-50.f, gain_to_apply_db);
52 RTC_DCHECK_LE(gain_to_apply_db, 50.f);
53 const float previous_applied_gained = gain_to_apply_;
54 gain_to_apply_ = DbToRatio(gain_to_apply_db);
55 RTC_DCHECK_LT(0.f, gain_to_apply_);
56 RTC_DLOG(LS_INFO) << "Gain to apply: " << gain_to_apply_db << " db.";
57 // Reset the gain curve applier to quickly react on abrupt level changes
58 // caused by large changes of the applied gain.
59 if (previous_applied_gained != gain_to_apply_) {
60 limiter_.Reset();
61 }
62 }
63
SetSampleRate(size_t sample_rate_hz)64 void FixedGainController::SetSampleRate(size_t sample_rate_hz) {
65 limiter_.SetSampleRate(sample_rate_hz);
66 }
67
Process(AudioFrameView<float> signal)68 void FixedGainController::Process(AudioFrameView<float> signal) {
69 // Apply fixed digital gain. One of the
70 // planned usages of the FGC is to only use the limiter. In that
71 // case, the gain would be 1.0. Not doing the multiplications speeds
72 // it up considerably. Hence the check.
73 if (!CloseToOne(gain_to_apply_)) {
74 for (size_t k = 0; k < signal.num_channels(); ++k) {
75 rtc::ArrayView<float> channel_view = signal.channel(k);
76 for (auto& sample : channel_view) {
77 sample *= gain_to_apply_;
78 }
79 }
80 }
81
82 // Use the limiter.
83 limiter_.Process(signal);
84
85 // Dump data for debug.
86 const auto channel_view = signal.channel(0);
87 apm_data_dumper_->DumpRaw("agc2_fixed_digital_gain_curve_applier",
88 channel_view.size(), channel_view.data());
89 // Hard-clipping.
90 for (size_t k = 0; k < signal.num_channels(); ++k) {
91 rtc::ArrayView<float> channel_view = signal.channel(k);
92 for (auto& sample : channel_view) {
93 sample = rtc::SafeClamp(sample, kMinFloatS16Value, kMaxFloatS16Value);
94 }
95 }
96 }
97
LastAudioLevel() const98 float FixedGainController::LastAudioLevel() const {
99 return limiter_.LastAudioLevel();
100 }
101 } // namespace webrtc
102