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 "modules/webaudio/DelayDSPKernel.h" 30 31#include "core/platform/audio/AudioUtilities.h" 32#include <algorithm> 33 34using namespace std; 35 36namespace WebCore { 37 38const float SmoothingTimeConstant = 0.020f; // 20ms 39 40DelayDSPKernel::DelayDSPKernel(DelayProcessor* processor) 41 : AudioDSPKernel(processor) 42 , m_writeIndex(0) 43 , m_firstTime(true) 44 , m_delayTimes(AudioNode::ProcessingSizeInFrames) 45{ 46 ASSERT(processor && processor->sampleRate() > 0); 47 if (!(processor && processor->sampleRate() > 0)) 48 return; 49 50 m_maxDelayTime = processor->maxDelayTime(); 51 ASSERT(m_maxDelayTime >= 0); 52 if (m_maxDelayTime < 0) 53 return; 54 55 m_buffer.allocate(bufferLengthForDelay(m_maxDelayTime, processor->sampleRate())); 56 m_buffer.zero(); 57 58 m_smoothingRate = AudioUtilities::discreteTimeConstantForSampleRate(SmoothingTimeConstant, processor->sampleRate()); 59} 60 61DelayDSPKernel::DelayDSPKernel(double maxDelayTime, float sampleRate) 62 : AudioDSPKernel(sampleRate) 63 , m_maxDelayTime(maxDelayTime) 64 , m_writeIndex(0) 65 , m_firstTime(true) 66{ 67 ASSERT(maxDelayTime > 0.0); 68 if (maxDelayTime <= 0.0) 69 return; 70 71 size_t bufferLength = bufferLengthForDelay(maxDelayTime, sampleRate); 72 ASSERT(bufferLength); 73 if (!bufferLength) 74 return; 75 76 m_buffer.allocate(bufferLength); 77 m_buffer.zero(); 78 79 m_smoothingRate = AudioUtilities::discreteTimeConstantForSampleRate(SmoothingTimeConstant, sampleRate); 80} 81 82size_t DelayDSPKernel::bufferLengthForDelay(double maxDelayTime, double sampleRate) const 83{ 84 // Compute the length of the buffer needed to handle a max delay of |maxDelayTime|. One is 85 // added to handle the case where the actual delay equals the maximum delay. 86 return 1 + AudioUtilities::timeToSampleFrame(maxDelayTime, sampleRate); 87} 88 89void DelayDSPKernel::process(const float* source, float* destination, size_t framesToProcess) 90{ 91 size_t bufferLength = m_buffer.size(); 92 float* buffer = m_buffer.data(); 93 94 ASSERT(bufferLength); 95 if (!bufferLength) 96 return; 97 98 ASSERT(source && destination); 99 if (!source || !destination) 100 return; 101 102 float sampleRate = this->sampleRate(); 103 double delayTime = 0; 104 float* delayTimes = m_delayTimes.data(); 105 double maxTime = maxDelayTime(); 106 107 bool sampleAccurate = delayProcessor() && delayProcessor()->delayTime()->hasSampleAccurateValues(); 108 109 if (sampleAccurate) 110 delayProcessor()->delayTime()->calculateSampleAccurateValues(delayTimes, framesToProcess); 111 else { 112 delayTime = delayProcessor() ? delayProcessor()->delayTime()->finalValue() : m_desiredDelayFrames / sampleRate; 113 114 // Make sure the delay time is in a valid range. 115 delayTime = min(maxTime, delayTime); 116 delayTime = max(0.0, delayTime); 117 118 if (m_firstTime) { 119 m_currentDelayTime = delayTime; 120 m_firstTime = false; 121 } 122 } 123 124 for (unsigned i = 0; i < framesToProcess; ++i) { 125 if (sampleAccurate) { 126 delayTime = delayTimes[i]; 127 delayTime = std::min(maxTime, delayTime); 128 delayTime = std::max(0.0, delayTime); 129 m_currentDelayTime = delayTime; 130 } else { 131 // Approach desired delay time. 132 m_currentDelayTime += (delayTime - m_currentDelayTime) * m_smoothingRate; 133 } 134 135 double desiredDelayFrames = m_currentDelayTime * sampleRate; 136 137 double readPosition = m_writeIndex + bufferLength - desiredDelayFrames; 138 if (readPosition >= bufferLength) 139 readPosition -= bufferLength; 140 141 // Linearly interpolate in-between delay times. 142 int readIndex1 = static_cast<int>(readPosition); 143 int readIndex2 = (readIndex1 + 1) % bufferLength; 144 double interpolationFactor = readPosition - readIndex1; 145 146 double input = static_cast<float>(*source++); 147 buffer[m_writeIndex] = static_cast<float>(input); 148 m_writeIndex = (m_writeIndex + 1) % bufferLength; 149 150 double sample1 = buffer[readIndex1]; 151 double sample2 = buffer[readIndex2]; 152 153 double output = (1.0 - interpolationFactor) * sample1 + interpolationFactor * sample2; 154 155 *destination++ = static_cast<float>(output); 156 } 157} 158 159void DelayDSPKernel::reset() 160{ 161 m_firstTime = true; 162 m_buffer.zero(); 163} 164 165double DelayDSPKernel::tailTime() const 166{ 167 // Account for worst case delay. 168 // Don't try to track actual delay time which can change dynamically. 169 return m_maxDelayTime; 170} 171 172double DelayDSPKernel::latencyTime() const 173{ 174 return 0; 175} 176 177} // namespace WebCore 178 179#endif // ENABLE(WEB_AUDIO) 180