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