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1 /* | |
2 * Copyright (c) 2017 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 #ifndef WEBRTC_MODULES_AUDIO_PROCESSING_TEST_ANALOG_VOLUME_MAPPER_H_ | |
12 #define WEBRTC_MODULES_AUDIO_PROCESSING_TEST_ANALOG_VOLUME_MAPPER_H_ | |
13 | |
14 #include "webrtc/base/checks.h" | |
15 | |
16 namespace webrtc { | |
17 | |
18 // Class for simulating an analog gain controller controlled by | |
19 // webrtc::GainControl. The class wraps a mapping from the current | |
20 // level to a floating point scaling factor abstracting | |
21 // non-linearities in the gain curve of real analog microphones. The | |
22 // intended mode of operation is to use get_scaling_factor() to apply | |
23 // a gain factor to a signal. | |
24 class AnalogLevelMapper { | |
25 public: | |
26 enum class LevelToScalingMappingKind { | |
peah-webrtc
2017/04/26 07:20:03
I really think it would be easier to see how to be
| |
27 kIdentity, // Any level produces a constant scaling factor of 1.0f. | |
28 kLinear // A level within [0, 255] is linearly scaled. 0 produces | |
29 // 0.f, and 255 is 1.0f. | |
30 }; | |
31 | |
32 explicit AnalogLevelMapper(LevelToScalingMappingKind mapping_kind) | |
33 : mapping_kind_(mapping_kind) {} | |
34 | |
35 // |level| must be within [0, 255]. | |
36 void set_analog_level(int level) { | |
37 RTC_DCHECK_LE(0, level); | |
38 RTC_DCHECK_LE(level, 255); | |
39 level_ = level; | |
40 } | |
41 | |
42 int analog_level() const { return level_; } | |
43 | |
44 float GetScalingFactor() const { | |
45 switch (mapping_kind_) { | |
46 case LevelToScalingMappingKind::kIdentity: { | |
47 return 1.0f; | |
48 } | |
49 case LevelToScalingMappingKind::kLinear: { | |
50 return static_cast<float>(level_) / 255.0f; | |
51 } | |
52 } | |
53 } | |
54 | |
55 private: | |
56 int level_ = 0; | |
57 const LevelToScalingMappingKind mapping_kind_; | |
58 }; | |
59 } // namespace webrtc | |
60 | |
61 #endif // WEBRTC_MODULES_AUDIO_PROCESSING_TEST_ANALOG_VOLUME_MAPPER_H_ | |
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