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      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/ConvolverNode.h"
     30 
     31 #include "core/platform/audio/Reverb.h"
     32 #include "modules/webaudio/AudioBuffer.h"
     33 #include "modules/webaudio/AudioContext.h"
     34 #include "modules/webaudio/AudioNodeInput.h"
     35 #include "modules/webaudio/AudioNodeOutput.h"
     36 #include "wtf/MainThread.h"
     37 
     38 // Note about empirical tuning:
     39 // The maximum FFT size affects reverb performance and accuracy.
     40 // If the reverb is single-threaded and processes entirely in the real-time audio thread,
     41 // it's important not to make this too high.  In this case 8192 is a good value.
     42 // But, the Reverb object is multi-threaded, so we want this as high as possible without losing too much accuracy.
     43 // Very large FFTs will have worse phase errors. Given these constraints 32768 is a good compromise.
     44 const size_t MaxFFTSize = 32768;
     45 
     46 namespace WebCore {
     47 
     48 ConvolverNode::ConvolverNode(AudioContext* context, float sampleRate)
     49     : AudioNode(context, sampleRate)
     50     , m_normalize(true)
     51 {
     52     ScriptWrappable::init(this);
     53     addInput(adoptPtr(new AudioNodeInput(this)));
     54     addOutput(adoptPtr(new AudioNodeOutput(this, 2)));
     55 
     56     // Node-specific default mixing rules.
     57     m_channelCount = 2;
     58     m_channelCountMode = ClampedMax;
     59     m_channelInterpretation = AudioBus::Speakers;
     60 
     61     setNodeType(NodeTypeConvolver);
     62     initialize();
     63 }
     64 
     65 ConvolverNode::~ConvolverNode()
     66 {
     67     uninitialize();
     68 }
     69 
     70 void ConvolverNode::process(size_t framesToProcess)
     71 {
     72     AudioBus* outputBus = output(0)->bus();
     73     ASSERT(outputBus);
     74 
     75     // Synchronize with possible dynamic changes to the impulse response.
     76     MutexTryLocker tryLocker(m_processLock);
     77     if (tryLocker.locked()) {
     78         if (!isInitialized() || !m_reverb.get())
     79             outputBus->zero();
     80         else {
     81             // Process using the convolution engine.
     82             // Note that we can handle the case where nothing is connected to the input, in which case we'll just feed silence into the convolver.
     83             // FIXME:  If we wanted to get fancy we could try to factor in the 'tail time' and stop processing once the tail dies down if
     84             // we keep getting fed silence.
     85             m_reverb->process(input(0)->bus(), outputBus, framesToProcess);
     86         }
     87     } else {
     88         // Too bad - the tryLock() failed.  We must be in the middle of setting a new impulse response.
     89         outputBus->zero();
     90     }
     91 }
     92 
     93 void ConvolverNode::reset()
     94 {
     95     MutexLocker locker(m_processLock);
     96     if (m_reverb.get())
     97         m_reverb->reset();
     98 }
     99 
    100 void ConvolverNode::initialize()
    101 {
    102     if (isInitialized())
    103         return;
    104 
    105     AudioNode::initialize();
    106 }
    107 
    108 void ConvolverNode::uninitialize()
    109 {
    110     if (!isInitialized())
    111         return;
    112 
    113     m_reverb.clear();
    114     AudioNode::uninitialize();
    115 }
    116 
    117 void ConvolverNode::setBuffer(AudioBuffer* buffer)
    118 {
    119     ASSERT(isMainThread());
    120 
    121     if (!buffer)
    122         return;
    123 
    124     unsigned numberOfChannels = buffer->numberOfChannels();
    125     size_t bufferLength = buffer->length();
    126 
    127     // The current implementation supports up to four channel impulse responses, which are interpreted as true-stereo (see Reverb class).
    128     bool isBufferGood = numberOfChannels > 0 && numberOfChannels <= 4 && bufferLength;
    129     ASSERT(isBufferGood);
    130     if (!isBufferGood)
    131         return;
    132 
    133     // Wrap the AudioBuffer by an AudioBus. It's an efficient pointer set and not a memcpy().
    134     // This memory is simply used in the Reverb constructor and no reference to it is kept for later use in that class.
    135     RefPtr<AudioBus> bufferBus = AudioBus::create(numberOfChannels, bufferLength, false);
    136     for (unsigned i = 0; i < numberOfChannels; ++i)
    137         bufferBus->setChannelMemory(i, buffer->getChannelData(i)->data(), bufferLength);
    138 
    139     bufferBus->setSampleRate(buffer->sampleRate());
    140 
    141     // Create the reverb with the given impulse response.
    142     bool useBackgroundThreads = !context()->isOfflineContext();
    143     OwnPtr<Reverb> reverb = adoptPtr(new Reverb(bufferBus.get(), AudioNode::ProcessingSizeInFrames, MaxFFTSize, 2, useBackgroundThreads, m_normalize));
    144 
    145     {
    146         // Synchronize with process().
    147         MutexLocker locker(m_processLock);
    148         m_reverb = reverb.release();
    149         m_buffer = buffer;
    150     }
    151 }
    152 
    153 AudioBuffer* ConvolverNode::buffer()
    154 {
    155     ASSERT(isMainThread());
    156     return m_buffer.get();
    157 }
    158 
    159 double ConvolverNode::tailTime() const
    160 {
    161     MutexTryLocker tryLocker(m_processLock);
    162     if (tryLocker.locked())
    163         return m_reverb ? m_reverb->impulseResponseLength() / static_cast<double>(sampleRate()) : 0;
    164     // Since we don't want to block the Audio Device thread, we return a large value
    165     // instead of trying to acquire the lock.
    166     return std::numeric_limits<double>::infinity();
    167 }
    168 
    169 double ConvolverNode::latencyTime() const
    170 {
    171     MutexTryLocker tryLocker(m_processLock);
    172     if (tryLocker.locked())
    173         return m_reverb ? m_reverb->latencyFrames() / static_cast<double>(sampleRate()) : 0;
    174     // Since we don't want to block the Audio Device thread, we return a large value
    175     // instead of trying to acquire the lock.
    176     return std::numeric_limits<double>::infinity();
    177 }
    178 
    179 } // namespace WebCore
    180 
    181 #endif // ENABLE(WEB_AUDIO)
    182