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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 "platform/audio/StereoPanner.h" | 5 #include "platform/audio/StereoPanner.h" |
6 #include "platform/audio/AudioBus.h" | 6 #include "platform/audio/AudioBus.h" |
7 #include "platform/audio/AudioUtilities.h" | 7 #include "platform/audio/AudioUtilities.h" |
8 #include "wtf/MathExtras.h" | 8 #include "wtf/MathExtras.h" |
9 #include <algorithm> | 9 #include <algorithm> |
10 | 10 |
11 // Use a 50ms smoothing / de-zippering time-constant. | 11 // Use a 50ms smoothing / de-zippering time-constant. |
12 const float SmoothingTimeConstant = 0.050f; | 12 const float SmoothingTimeConstant = 0.050f; |
13 | 13 |
14 namespace blink { | 14 namespace blink { |
15 | 15 |
16 // Implement equal-power panning algorithm for mono or stereo input. | 16 // Implement equal-power panning algorithm for mono or stereo input. |
17 // See: http://webaudio.github.io/web-audio-api/#panning-algorithm | 17 // See: http://webaudio.github.io/web-audio-api/#panning-algorithm |
18 | 18 |
19 std::unique_ptr<StereoPanner> StereoPanner::create(float sampleRate) { | 19 std::unique_ptr<StereoPanner> StereoPanner::create(float sampleRate) { |
20 return wrapUnique(new StereoPanner(sampleRate)); | 20 return WTF::wrapUnique(new StereoPanner(sampleRate)); |
21 } | 21 } |
22 | 22 |
23 StereoPanner::StereoPanner(float sampleRate) | 23 StereoPanner::StereoPanner(float sampleRate) |
24 : m_isFirstRender(true), m_pan(0.0) { | 24 : m_isFirstRender(true), m_pan(0.0) { |
25 // Convert smoothing time (50ms) to a per-sample time value. | 25 // Convert smoothing time (50ms) to a per-sample time value. |
26 m_smoothingConstant = AudioUtilities::discreteTimeConstantForSampleRate( | 26 m_smoothingConstant = AudioUtilities::discreteTimeConstantForSampleRate( |
27 SmoothingTimeConstant, sampleRate); | 27 SmoothingTimeConstant, sampleRate); |
28 } | 28 } |
29 | 29 |
30 void StereoPanner::panWithSampleAccurateValues(const AudioBus* inputBus, | 30 void StereoPanner::panWithSampleAccurateValues(const AudioBus* inputBus, |
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172 // When [0; 1], keep right channel intact and equal-power pan the | 172 // When [0; 1], keep right channel intact and equal-power pan the |
173 // left channel only. | 173 // left channel only. |
174 *destinationL++ = static_cast<float>(inputL * gainL); | 174 *destinationL++ = static_cast<float>(inputL * gainL); |
175 *destinationR++ = static_cast<float>(inputR + inputL * gainR); | 175 *destinationR++ = static_cast<float>(inputR + inputL * gainR); |
176 } | 176 } |
177 } | 177 } |
178 } | 178 } |
179 } | 179 } |
180 | 180 |
181 } // namespace blink | 181 } // namespace blink |
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