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 "platform/audio/AudioDelayDSPKernel.h" 30 31#include "platform/audio/AudioUtilities.h" 32#include "wtf/MathExtras.h" 33#include <algorithm> 34 35namespace blink { 36 37const float SmoothingTimeConstant = 0.020f; // 20ms 38 39AudioDelayDSPKernel::AudioDelayDSPKernel(AudioDSPKernelProcessor* processor, size_t processingSizeInFrames) 40 : AudioDSPKernel(processor) 41 , m_writeIndex(0) 42 , m_firstTime(true) 43 , m_delayTimes(processingSizeInFrames) 44{ 45} 46 47AudioDelayDSPKernel::AudioDelayDSPKernel(double maxDelayTime, float sampleRate) 48 : AudioDSPKernel(sampleRate) 49 , m_maxDelayTime(maxDelayTime) 50 , m_writeIndex(0) 51 , m_firstTime(true) 52{ 53 ASSERT(maxDelayTime > 0.0 && !std::isnan(maxDelayTime)); 54 if (maxDelayTime <= 0.0 || std::isnan(maxDelayTime)) 55 return; 56 57 size_t bufferLength = bufferLengthForDelay(maxDelayTime, sampleRate); 58 ASSERT(bufferLength); 59 if (!bufferLength) 60 return; 61 62 m_buffer.allocate(bufferLength); 63 m_buffer.zero(); 64 65 m_smoothingRate = AudioUtilities::discreteTimeConstantForSampleRate(SmoothingTimeConstant, sampleRate); 66} 67 68size_t AudioDelayDSPKernel::bufferLengthForDelay(double maxDelayTime, double sampleRate) const 69{ 70 // Compute the length of the buffer needed to handle a max delay of |maxDelayTime|. One is 71 // added to handle the case where the actual delay equals the maximum delay. 72 return 1 + AudioUtilities::timeToSampleFrame(maxDelayTime, sampleRate); 73} 74 75bool AudioDelayDSPKernel::hasSampleAccurateValues() 76{ 77 return false; 78} 79 80void AudioDelayDSPKernel::calculateSampleAccurateValues(float*, size_t) 81{ 82 ASSERT_NOT_REACHED(); 83} 84 85double AudioDelayDSPKernel::delayTime(float sampleRate) 86{ 87 return m_desiredDelayFrames / sampleRate; 88} 89 90void AudioDelayDSPKernel::process(const float* source, float* destination, size_t framesToProcess) 91{ 92 size_t bufferLength = m_buffer.size(); 93 float* buffer = m_buffer.data(); 94 95 ASSERT(bufferLength); 96 if (!bufferLength) 97 return; 98 99 ASSERT(source && destination); 100 if (!source || !destination) 101 return; 102 103 float sampleRate = this->sampleRate(); 104 double delayTime = 0; 105 float* delayTimes = m_delayTimes.data(); 106 double maxTime = maxDelayTime(); 107 108 bool sampleAccurate = hasSampleAccurateValues(); 109 110 if (sampleAccurate) { 111 calculateSampleAccurateValues(delayTimes, framesToProcess); 112 } else { 113 delayTime = this->delayTime(sampleRate); 114 115 // Make sure the delay time is in a valid range. 116 delayTime = std::min(maxTime, delayTime); 117 delayTime = std::max(0.0, delayTime); 118 119 if (m_firstTime) { 120 m_currentDelayTime = delayTime; 121 m_firstTime = false; 122 } 123 } 124 125 for (unsigned i = 0; i < framesToProcess; ++i) { 126 if (sampleAccurate) { 127 delayTime = delayTimes[i]; 128 delayTime = std::min(maxTime, delayTime); 129 delayTime = std::max(0.0, delayTime); 130 m_currentDelayTime = delayTime; 131 } else { 132 // Approach desired delay time. 133 m_currentDelayTime += (delayTime - m_currentDelayTime) * m_smoothingRate; 134 } 135 136 double desiredDelayFrames = m_currentDelayTime * sampleRate; 137 138 double readPosition = m_writeIndex + bufferLength - desiredDelayFrames; 139 if (readPosition >= bufferLength) 140 readPosition -= bufferLength; 141 142 // Linearly interpolate in-between delay times. 143 int readIndex1 = static_cast<int>(readPosition); 144 int readIndex2 = (readIndex1 + 1) % bufferLength; 145 double interpolationFactor = readPosition - readIndex1; 146 147 double input = static_cast<float>(*source++); 148 buffer[m_writeIndex] = static_cast<float>(input); 149 m_writeIndex = (m_writeIndex + 1) % bufferLength; 150 151 double sample1 = buffer[readIndex1]; 152 double sample2 = buffer[readIndex2]; 153 154 double output = (1.0 - interpolationFactor) * sample1 + interpolationFactor * sample2; 155 156 *destination++ = static_cast<float>(output); 157 } 158} 159 160void AudioDelayDSPKernel::reset() 161{ 162 m_firstTime = true; 163 m_buffer.zero(); 164} 165 166double AudioDelayDSPKernel::tailTime() const 167{ 168 // Account for worst case delay. 169 // Don't try to track actual delay time which can change dynamically. 170 return m_maxDelayTime; 171} 172 173double AudioDelayDSPKernel::latencyTime() const 174{ 175 return 0; 176} 177 178} // namespace blink 179 180#endif // ENABLE(WEB_AUDIO) 181