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1 // Copyright 2017 The Chromium Authors. All rights reserved. | |
2 // Use of this source code is governed by a BSD-style license that can be | |
3 // found in the LICENSE file. | |
4 | |
5 #include <memory> | |
6 #include <string> | |
7 | |
8 #include "base/logging.h" | |
9 #include "base/macros.h" | |
10 #include "base/values.h" | |
11 #include "chromecast/base/serializers.h" | |
12 #include "chromecast/media/cma/backend/alsa/slew_volume.h" | |
13 #include "chromecast/public/media/audio_post_processor_shlib.h" | |
14 | |
15 namespace chromecast { | |
16 namespace media { | |
17 | |
18 namespace { | |
19 const int kNoSampleRate = -1; | |
20 | |
21 // Configuration strings: | |
22 const char kOnsetVolumeKey[] = "onset_volume"; | |
23 const char kClampMultiplierKey[] = "clamp_multiplier"; | |
24 | |
25 } // namespace | |
26 | |
27 // Provides a flat reduction in output volume if the input volume is above a | |
28 // given threshold. | |
29 // Used to protect speakers at high output levels | |
30 // while providing dyanmic range at low output level. | |
31 // The configuration string for this plugin is: | |
32 // {"onset_volume": |VOLUME_TO_CLAMP|, "clamp_multiplier": |CLAMP_MULTIPLIER|} | |
33 // Input volumes > |VOLUME_TO_CLAMP| will be attenuated by |CLAMP_MULTIPLIER|. | |
34 class Governor : public AudioPostProcessor { | |
35 public: | |
36 Governor(const std::string& config, int channels); | |
37 ~Governor() override; | |
38 | |
39 bool SetSampleRate(int sample_rate) override; | |
40 int ProcessFrames(uint8_t* data, int frames, float volume) override; | |
41 int GetRingingTimeInFrames() override; | |
42 | |
43 private: | |
44 float GetGovernorMultiplier(); | |
45 | |
46 int channels_; | |
47 int sample_rate_; | |
48 float volume_; | |
49 double onset_volume_; | |
50 double clamp_multiplier_; | |
51 SlewVolume governor_; | |
52 DISALLOW_COPY_AND_ASSIGN(Governor); | |
53 }; | |
54 | |
55 Governor::Governor(const std::string& config, int channels) | |
56 : channels_(channels), sample_rate_(kNoSampleRate), volume_(1.0) { | |
57 auto config_dict = base::DictionaryValue::From(DeserializeFromJson(config)); | |
58 CHECK(config_dict) << "Governor config is not valid json: " << config; | |
59 CHECK(config_dict->GetDouble(kOnsetVolumeKey, &onset_volume_)); | |
60 CHECK(config_dict->GetDouble(kClampMultiplierKey, &clamp_multiplier_)); | |
61 DCHECK_EQ(channels_, 2); | |
62 governor_.SetVolume(1.0); | |
63 LOG(INFO) << "Created a governor: onset_volume = " << onset_volume_ | |
64 << ", clamp_multiplier = " << clamp_multiplier_; | |
65 } | |
66 | |
67 Governor::~Governor() = default; | |
68 | |
69 bool Governor::SetSampleRate(int sample_rate) { | |
70 sample_rate_ = sample_rate; | |
71 governor_.SetSampleRate(sample_rate); | |
wzhong
2017/03/27 14:23:43
return governor_.SetSampleRate(sample_rate);
bshaya
2017/03/27 21:00:26
SlewVolume::SetSampleRate has void return type but
| |
72 return true; | |
73 } | |
74 | |
75 int Governor::ProcessFrames(uint8_t* data, int frames, float volume) { | |
76 if (volume != volume_) { | |
77 volume_ = volume; | |
78 governor_.SetVolume(GetGovernorMultiplier()); | |
79 } | |
80 | |
81 governor_.ProcessInterleaved(reinterpret_cast<int32_t*>(data), frames); | |
82 return 0; // No delay in this pipeline. | |
wzhong
2017/03/27 14:23:43
return governor_.ProcessInterleaved(reinterpret_ca
bshaya
2017/03/27 21:00:26
SlewVolume::ProcessInterleaved returns bool indica
| |
83 } | |
84 | |
85 int Governor::GetRingingTimeInFrames() { | |
86 return 0; | |
87 } | |
88 | |
89 float Governor::GetGovernorMultiplier() { | |
90 if (volume_ >= onset_volume_) { | |
91 return clamp_multiplier_; | |
92 } | |
93 return 1.0; | |
94 } | |
95 | |
96 } // namespace media | |
97 } // namespace chromecast | |
98 | |
99 chromecast::media::AudioPostProcessor* AudioPostProcessorShlib_Create( | |
100 const std::string& config, | |
101 int channels) { | |
102 return static_cast<chromecast::media::AudioPostProcessor*>( | |
103 new chromecast::media::Governor(config, channels)); | |
104 } | |
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