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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> | |
9 | 8 |
10 #include "base/logging.h" | 9 #include "base/logging.h" |
11 #include "base/stl_util.h" | 10 #include "base/stl_util.h" |
12 #include "media/base/audio_bus.h" | 11 #include "media/base/audio_bus.h" |
13 | 12 |
14 namespace content { | 13 namespace content { |
15 | 14 |
16 namespace { | 15 namespace { |
17 | 16 |
18 // Calculates the maximum absolute amplitude of the audio data. | 17 // Calculates the maximum absolute amplitude of the audio data. |
19 float MaxAmplitude(const float* audio_data, int length) { | 18 float MaxAmplitude(const float* audio_data, int length) { |
20 float max = 0.0f; | 19 float max = 0.0f; |
21 for (int i = 0; i < length; ++i) { | 20 for (int i = 0; i < length; ++i) { |
22 const float absolute = fabsf(audio_data[i]); | 21 const float absolute = fabsf(audio_data[i]); |
23 if (absolute > max) | 22 if (absolute > max) |
24 max = absolute; | 23 max = absolute; |
25 } | 24 } |
26 DCHECK(std::isfinite(max)); | 25 DCHECK(std::isfinite(max)); |
27 return max; | 26 return max; |
28 } | 27 } |
29 | 28 |
30 } // namespace | 29 } // namespace |
31 | 30 |
32 MediaStreamAudioLevelCalculator::Level::Level() : level_(0.0f) {} | 31 MediaStreamAudioLevelCalculator::MediaStreamAudioLevelCalculator() |
33 | 32 : counter_(0), |
34 MediaStreamAudioLevelCalculator::Level::~Level() {} | 33 max_amplitude_(0.0f), |
35 | 34 level_(0.0f) { |
36 float MediaStreamAudioLevelCalculator::Level::GetCurrent() const { | |
37 base::AutoLock auto_lock(lock_); | |
38 return level_; | |
39 } | 35 } |
40 | 36 |
41 void MediaStreamAudioLevelCalculator::Level::Set(float level) { | 37 MediaStreamAudioLevelCalculator::~MediaStreamAudioLevelCalculator() { |
42 base::AutoLock auto_lock(lock_); | |
43 level_ = level; | |
44 } | 38 } |
45 | 39 |
46 MediaStreamAudioLevelCalculator::MediaStreamAudioLevelCalculator() | 40 float MediaStreamAudioLevelCalculator::Calculate( |
47 : counter_(0), max_amplitude_(0.0f), level_(new Level()) {} | 41 const media::AudioBus& audio_bus) { |
48 | 42 DCHECK(thread_checker_.CalledOnValidThread()); |
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) { | |
56 // |level_| is updated every 10 callbacks. For the case where callback comes | 43 // |level_| is updated every 10 callbacks. For the case where callback comes |
57 // every 10ms, |level_| will be updated approximately every 100ms. | 44 // every 10ms, |level_| will be updated approximately every 100ms. |
58 static const int kUpdateFrequency = 10; | 45 static const int kUpdateFrequency = 10; |
59 | 46 |
60 float max = | 47 float max = 0.0f; |
61 assume_nonzero_energy ? 1.0f / std::numeric_limits<int16_t>::max() : 0.0f; | |
62 for (int i = 0; i < audio_bus.channels(); ++i) { | 48 for (int i = 0; i < audio_bus.channels(); ++i) { |
63 const float max_this_channel = | 49 const float max_this_channel = |
64 MaxAmplitude(audio_bus.channel(i), audio_bus.frames()); | 50 MaxAmplitude(audio_bus.channel(i), audio_bus.frames()); |
65 if (max_this_channel > max) | 51 if (max_this_channel > max) |
66 max = max_this_channel; | 52 max = max_this_channel; |
67 } | 53 } |
68 max_amplitude_ = std::max(max_amplitude_, max); | 54 max_amplitude_ = std::max(max_amplitude_, max); |
69 | 55 |
70 if (counter_++ == kUpdateFrequency) { | 56 if (counter_++ == kUpdateFrequency) { |
71 // Clip the exposed signal level to make sure it is in the range [0.0,1.0]. | 57 level_ = max_amplitude_; |
72 level_->Set(std::min(1.0f, max_amplitude_)); | |
73 | 58 |
74 // Decay the absolute maximum amplitude by 1/4. | 59 // Decay the absolute maximum amplitude by 1/4. |
75 max_amplitude_ /= 4.0f; | 60 max_amplitude_ /= 4.0f; |
76 | 61 |
77 // Reset the counter. | 62 // Reset the counter. |
78 counter_ = 0; | 63 counter_ = 0; |
79 } | 64 } |
| 65 |
| 66 return level_; |
80 } | 67 } |
81 | 68 |
82 } // namespace content | 69 } // namespace content |
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