1/*
2 * Copyright (C) 2010, Google Inc. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
12 *
13 * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS'' AND ANY
14 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
15 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
16 * DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS BE LIABLE FOR ANY
17 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
18 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
19 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
20 * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
21 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
22 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
23 */
24
25#include "config.h"
26
27#if ENABLE(WEB_AUDIO)
28
29#include "DelayDSPKernel.h"
30
31#include "AudioUtilities.h"
32#include <algorithm>
33
34namespace WebCore {
35
36const float SmoothingTimeConstant = 0.020f; // 20ms
37
38DelayDSPKernel::DelayDSPKernel(DelayProcessor* processor)
39 : AudioDSPKernel(processor)
40 , m_writeIndex(0)
41 , m_firstTime(true)
42 , m_delayTimes(AudioNode::ProcessingSizeInFrames)
43{
44 ASSERT(processor && processor->sampleRate() > 0);
45 if (!(processor && processor->sampleRate() > 0))
46 return;
47
48 m_maxDelayTime = processor->maxDelayTime();
49 ASSERT(m_maxDelayTime >= 0);
50 if (m_maxDelayTime < 0)
51 return;
52
53 m_buffer.allocate(bufferLengthForDelay(m_maxDelayTime, processor->sampleRate()));
54 m_buffer.zero();
55
56 m_smoothingRate = AudioUtilities::discreteTimeConstantForSampleRate(SmoothingTimeConstant, processor->sampleRate());
57}
58
59DelayDSPKernel::DelayDSPKernel(double maxDelayTime, float sampleRate)
60 : AudioDSPKernel(sampleRate)
61 , m_maxDelayTime(maxDelayTime)
62 , m_writeIndex(0)
63 , m_firstTime(true)
64{
65 ASSERT(maxDelayTime > 0.0);
66 if (maxDelayTime <= 0.0)
67 return;
68
69 size_t bufferLength = bufferLengthForDelay(maxDelayTime, sampleRate);
70 ASSERT(bufferLength);
71 if (!bufferLength)
72 return;
73
74 m_buffer.allocate(bufferLength);
75 m_buffer.zero();
76
77 m_smoothingRate = AudioUtilities::discreteTimeConstantForSampleRate(SmoothingTimeConstant, sampleRate);
78}
79
80size_t DelayDSPKernel::bufferLengthForDelay(double maxDelayTime, double sampleRate) const
81{
82 // Compute the length of the buffer needed to handle a max delay of |maxDelayTime|. One is
83 // added to handle the case where the actual delay equals the maximum delay.
84 return 1 + AudioUtilities::timeToSampleFrame(maxDelayTime, sampleRate);
85}
86
87void DelayDSPKernel::process(const float* source, float* destination, size_t framesToProcess)
88{
89 size_t bufferLength = m_buffer.size();
90 float* buffer = m_buffer.data();
91
92 ASSERT(bufferLength);
93 if (!bufferLength)
94 return;
95
96 ASSERT(source && destination);
97 if (!source || !destination)
98 return;
99
100 float sampleRate = this->sampleRate();
101 double delayTime = 0;
102 float* delayTimes = m_delayTimes.data();
103 double maxTime = maxDelayTime();
104
105 bool sampleAccurate = delayProcessor() && delayProcessor()->delayTime()->hasSampleAccurateValues();
106
107 if (sampleAccurate)
108 delayProcessor()->delayTime()->calculateSampleAccurateValues(delayTimes, framesToProcess);
109 else {
110 delayTime = delayProcessor() ? delayProcessor()->delayTime()->finalValue() : m_desiredDelayFrames / sampleRate;
111
112 // Make sure the delay time is in a valid range.
113 delayTime = std::min(maxTime, delayTime);
114 delayTime = std::max(0.0, delayTime);
115
116 if (m_firstTime) {
117 m_currentDelayTime = delayTime;
118 m_firstTime = false;
119 }
120 }
121
122 for (unsigned i = 0; i < framesToProcess; ++i) {
123 if (sampleAccurate) {
124 delayTime = delayTimes[i];
125 delayTime = std::min(maxTime, delayTime);
126 delayTime = std::max(0.0, delayTime);
127 m_currentDelayTime = delayTime;
128 } else {
129 // Approach desired delay time.
130 m_currentDelayTime += (delayTime - m_currentDelayTime) * m_smoothingRate;
131 }
132
133 double desiredDelayFrames = m_currentDelayTime * sampleRate;
134
135 double readPosition = m_writeIndex + bufferLength - desiredDelayFrames;
136 if (readPosition >= bufferLength)
137 readPosition -= bufferLength;
138
139 // Linearly interpolate in-between delay times.
140 int readIndex1 = static_cast<int>(readPosition);
141 int readIndex2 = (readIndex1 + 1) % bufferLength;
142 double interpolationFactor = readPosition - readIndex1;
143
144 double input = static_cast<float>(*source++);
145 buffer[m_writeIndex] = static_cast<float>(input);
146 m_writeIndex = (m_writeIndex + 1) % bufferLength;
147
148 double sample1 = buffer[readIndex1];
149 double sample2 = buffer[readIndex2];
150
151 double output = (1.0 - interpolationFactor) * sample1 + interpolationFactor * sample2;
152
153 *destination++ = static_cast<float>(output);
154 }
155}
156
157void DelayDSPKernel::reset()
158{
159 m_firstTime = true;
160 m_buffer.zero();
161}
162
163double DelayDSPKernel::tailTime() const
164{
165 return m_maxDelayTime;
166}
167
168double DelayDSPKernel::latencyTime() const
169{
170 return 0;
171}
172
173} // namespace WebCore
174
175#endif // ENABLE(WEB_AUDIO)
176