1 /*
2 * Copyright (c) 2012 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 "audio/audio_level.h"
12
13 #include "api/audio/audio_frame.h"
14 #include "common_audio/signal_processing/include/signal_processing_library.h"
15
16 namespace webrtc {
17 namespace voe {
18
AudioLevel()19 AudioLevel::AudioLevel()
20 : abs_max_(0), count_(0), current_level_full_range_(0) {}
21
~AudioLevel()22 AudioLevel::~AudioLevel() {}
23
Reset()24 void AudioLevel::Reset() {
25 MutexLock lock(&mutex_);
26 abs_max_ = 0;
27 count_ = 0;
28 current_level_full_range_ = 0;
29 total_energy_ = 0.0;
30 total_duration_ = 0.0;
31 }
32
LevelFullRange() const33 int16_t AudioLevel::LevelFullRange() const {
34 MutexLock lock(&mutex_);
35 return current_level_full_range_;
36 }
37
ResetLevelFullRange()38 void AudioLevel::ResetLevelFullRange() {
39 MutexLock lock(&mutex_);
40 abs_max_ = 0;
41 count_ = 0;
42 current_level_full_range_ = 0;
43 }
44
TotalEnergy() const45 double AudioLevel::TotalEnergy() const {
46 MutexLock lock(&mutex_);
47 return total_energy_;
48 }
49
TotalDuration() const50 double AudioLevel::TotalDuration() const {
51 MutexLock lock(&mutex_);
52 return total_duration_;
53 }
54
ComputeLevel(const AudioFrame & audioFrame,double duration)55 void AudioLevel::ComputeLevel(const AudioFrame& audioFrame, double duration) {
56 // Check speech level (works for 2 channels as well)
57 int16_t abs_value =
58 audioFrame.muted()
59 ? 0
60 : WebRtcSpl_MaxAbsValueW16(
61 audioFrame.data(),
62 audioFrame.samples_per_channel_ * audioFrame.num_channels_);
63
64 // Protect member access using a lock since this method is called on a
65 // dedicated audio thread in the RecordedDataIsAvailable() callback.
66 MutexLock lock(&mutex_);
67
68 if (abs_value > abs_max_)
69 abs_max_ = abs_value;
70
71 // Update level approximately 9 times per second, assuming audio frame
72 // duration is approximately 10 ms. (The update frequency is every
73 // 11th (= |kUpdateFrequency+1|) call: 1000/(11*10)=9.09..., we should
74 // probably change this behavior, see https://crbug.com/webrtc/10784).
75 if (count_++ == kUpdateFrequency) {
76 current_level_full_range_ = abs_max_;
77
78 count_ = 0;
79
80 // Decay the absolute maximum (divide by 4)
81 abs_max_ >>= 2;
82 }
83
84 // See the description for "totalAudioEnergy" in the WebRTC stats spec
85 // (https://w3c.github.io/webrtc-stats/#dom-rtcmediastreamtrackstats-totalaudioenergy)
86 // for an explanation of these formulas. In short, we need a value that can
87 // be used to compute RMS audio levels over different time intervals, by
88 // taking the difference between the results from two getStats calls. To do
89 // this, the value needs to be of units "squared sample value * time".
90 double additional_energy =
91 static_cast<double>(current_level_full_range_) / INT16_MAX;
92 additional_energy *= additional_energy;
93 total_energy_ += additional_energy * duration;
94 total_duration_ += duration;
95 }
96
97 } // namespace voe
98 } // namespace webrtc
99