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Side by Side Diff: content/renderer/media/media_stream_audio_level_calculator.cc

Issue 1721273002: MediaStream audio object graph untangling and clean-ups. (Closed) Base URL: https://chromium.googlesource.com/chromium/src.git@master
Patch Set: addressed o1ka's comments Created 4 years, 9 months ago
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1 // Copyright 2014 The Chromium Authors. All rights reserved. 1 // Copyright 2014 The Chromium Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be 2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file. 3 // found in the LICENSE file.
4 4
5 #include "content/renderer/media/media_stream_audio_level_calculator.h" 5 #include "content/renderer/media/media_stream_audio_level_calculator.h"
6 6
7 #include <cmath> 7 #include <cmath>
8 #include <limits>
8 9
9 #include "base/logging.h" 10 #include "base/logging.h"
10 #include "base/stl_util.h" 11 #include "base/stl_util.h"
11 #include "media/base/audio_bus.h" 12 #include "media/base/audio_bus.h"
12 13
13 namespace content { 14 namespace content {
14 15
15 namespace { 16 namespace {
16 17
17 // Calculates the maximum absolute amplitude of the audio data. 18 // Calculates the maximum absolute amplitude of the audio data.
18 float MaxAmplitude(const float* audio_data, int length) { 19 float MaxAmplitude(const float* audio_data, int length) {
19 float max = 0.0f; 20 float max = 0.0f;
20 for (int i = 0; i < length; ++i) { 21 for (int i = 0; i < length; ++i) {
21 const float absolute = fabsf(audio_data[i]); 22 const float absolute = fabsf(audio_data[i]);
22 if (absolute > max) 23 if (absolute > max)
23 max = absolute; 24 max = absolute;
24 } 25 }
25 DCHECK(std::isfinite(max)); 26 DCHECK(std::isfinite(max));
26 return max; 27 return max;
27 } 28 }
28 29
29 } // namespace 30 } // namespace
30 31
31 MediaStreamAudioLevelCalculator::MediaStreamAudioLevelCalculator() 32 MediaStreamAudioLevelCalculator::Level::Level() : level_(0.0f) {}
32 : counter_(0), 33
33 max_amplitude_(0.0f), 34 MediaStreamAudioLevelCalculator::Level::~Level() {}
34 level_(0.0f) { 35
36 float MediaStreamAudioLevelCalculator::Level::GetCurrent() const {
37 base::AutoLock auto_lock(lock_);
38 return level_;
35 } 39 }
36 40
37 MediaStreamAudioLevelCalculator::~MediaStreamAudioLevelCalculator() { 41 void MediaStreamAudioLevelCalculator::Level::Set(float level) {
42 base::AutoLock auto_lock(lock_);
43 level_ = level;
38 } 44 }
39 45
40 float MediaStreamAudioLevelCalculator::Calculate( 46 MediaStreamAudioLevelCalculator::MediaStreamAudioLevelCalculator()
41 const media::AudioBus& audio_bus) { 47 : counter_(0), max_amplitude_(0.0f), level_(new Level()) {}
42 DCHECK(thread_checker_.CalledOnValidThread()); 48
49 MediaStreamAudioLevelCalculator::~MediaStreamAudioLevelCalculator() {
50 level_->Set(0.0f);
51 }
52
53 void MediaStreamAudioLevelCalculator::Calculate(
54 const media::AudioBus& audio_bus,
55 bool assume_nonzero_energy) {
43 // |level_| is updated every 10 callbacks. For the case where callback comes 56 // |level_| is updated every 10 callbacks. For the case where callback comes
44 // every 10ms, |level_| will be updated approximately every 100ms. 57 // every 10ms, |level_| will be updated approximately every 100ms.
45 static const int kUpdateFrequency = 10; 58 static const int kUpdateFrequency = 10;
46 59
47 float max = 0.0f; 60 float max =
61 assume_nonzero_energy ? 1.0f / std::numeric_limits<int16_t>::max() : 0.0f;
48 for (int i = 0; i < audio_bus.channels(); ++i) { 62 for (int i = 0; i < audio_bus.channels(); ++i) {
49 const float max_this_channel = 63 const float max_this_channel =
50 MaxAmplitude(audio_bus.channel(i), audio_bus.frames()); 64 MaxAmplitude(audio_bus.channel(i), audio_bus.frames());
51 if (max_this_channel > max) 65 if (max_this_channel > max)
52 max = max_this_channel; 66 max = max_this_channel;
53 } 67 }
54 max_amplitude_ = std::max(max_amplitude_, max); 68 max_amplitude_ = std::max(max_amplitude_, max);
55 69
56 if (counter_++ == kUpdateFrequency) { 70 if (counter_++ == kUpdateFrequency) {
57 level_ = max_amplitude_; 71 // Clip the exposed signal level to make sure it is in the range [0.0,1.0].
72 level_->Set(std::min(1.0f, max_amplitude_));
58 73
59 // Decay the absolute maximum amplitude by 1/4. 74 // Decay the absolute maximum amplitude by 1/4.
60 max_amplitude_ /= 4.0f; 75 max_amplitude_ /= 4.0f;
61 76
62 // Reset the counter. 77 // Reset the counter.
63 counter_ = 0; 78 counter_ = 0;
64 } 79 }
65
66 return level_;
67 } 80 }
68 81
69 } // namespace content 82 } // namespace content
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