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 | |
34 | namespace WebCore { |
35 | |
36 | const float SmoothingTimeConstant = 0.020f; // 20ms |
37 | |
38 | DelayDSPKernel::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 | |
59 | DelayDSPKernel::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 | |
80 | size_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 | |
87 | void 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 | |
157 | void DelayDSPKernel::reset() |
158 | { |
159 | m_firstTime = true; |
160 | m_buffer.zero(); |
161 | } |
162 | |
163 | double DelayDSPKernel::tailTime() const |
164 | { |
165 | return m_maxDelayTime; |
166 | } |
167 | |
168 | double DelayDSPKernel::latencyTime() const |
169 | { |
170 | return 0; |
171 | } |
172 | |
173 | } // namespace WebCore |
174 | |
175 | #endif // ENABLE(WEB_AUDIO) |
176 | |