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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 "bindings/core/v8/ExceptionState.h"
     32 #include "core/dom/ExceptionCode.h"
     33 #include "platform/audio/Reverb.h"
     34 #include "modules/webaudio/AudioBuffer.h"
     35 #include "modules/webaudio/AudioContext.h"
     36 #include "modules/webaudio/AudioNodeInput.h"
     37 #include "modules/webaudio/AudioNodeOutput.h"
     38 #include "wtf/MainThread.h"
     39 
     40 // Note about empirical tuning:
     41 // The maximum FFT size affects reverb performance and accuracy.
     42 // If the reverb is single-threaded and processes entirely in the real-time audio thread,
     43 // it's important not to make this too high.  In this case 8192 is a good value.
     44 // But, the Reverb object is multi-threaded, so we want this as high as possible without losing too much accuracy.
     45 // Very large FFTs will have worse phase errors. Given these constraints 32768 is a good compromise.
     46 const size_t MaxFFTSize = 32768;
     47 
     48 namespace blink {
     49 
     50 ConvolverNode::ConvolverNode(AudioContext* context, float sampleRate)
     51     : AudioNode(context, sampleRate)
     52     , m_normalize(true)
     53 {
     54     addInput();
     55     addOutput(AudioNodeOutput::create(this, 2));
     56 
     57     // Node-specific default mixing rules.
     58     m_channelCount = 2;
     59     m_channelCountMode = ClampedMax;
     60     m_channelInterpretation = AudioBus::Speakers;
     61 
     62     setNodeType(NodeTypeConvolver);
     63     initialize();
     64 }
     65 
     66 ConvolverNode::~ConvolverNode()
     67 {
     68     ASSERT(!isInitialized());
     69 }
     70 
     71 void ConvolverNode::dispose()
     72 {
     73     uninitialize();
     74     AudioNode::dispose();
     75 }
     76 
     77 void ConvolverNode::process(size_t framesToProcess)
     78 {
     79     AudioBus* outputBus = output(0)->bus();
     80     ASSERT(outputBus);
     81 
     82     // Synchronize with possible dynamic changes to the impulse response.
     83     MutexTryLocker tryLocker(m_processLock);
     84     if (tryLocker.locked()) {
     85         if (!isInitialized() || !m_reverb.get())
     86             outputBus->zero();
     87         else {
     88             // Process using the convolution engine.
     89             // 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.
     90             // 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
     91             // we keep getting fed silence.
     92             m_reverb->process(input(0)->bus(), outputBus, framesToProcess);
     93         }
     94     } else {
     95         // Too bad - the tryLock() failed.  We must be in the middle of setting a new impulse response.
     96         outputBus->zero();
     97     }
     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, ExceptionState& exceptionState)
    118 {
    119     ASSERT(isMainThread());
    120 
    121     if (!buffer)
    122         return;
    123 
    124     if (buffer->sampleRate() != context()->sampleRate()) {
    125         exceptionState.throwDOMException(
    126             NotSupportedError,
    127             "The buffer sample rate of " + String::number(buffer->sampleRate())
    128             + " does not match the context rate of " + String::number(context()->sampleRate())
    129             + " Hz.");
    130     }
    131 
    132     unsigned numberOfChannels = buffer->numberOfChannels();
    133     size_t bufferLength = buffer->length();
    134 
    135     // The current implementation supports up to four channel impulse responses, which are interpreted as true-stereo (see Reverb class).
    136     bool isBufferGood = numberOfChannels > 0 && numberOfChannels <= 4 && bufferLength;
    137     ASSERT(isBufferGood);
    138     if (!isBufferGood)
    139         return;
    140 
    141     // Wrap the AudioBuffer by an AudioBus. It's an efficient pointer set and not a memcpy().
    142     // This memory is simply used in the Reverb constructor and no reference to it is kept for later use in that class.
    143     RefPtr<AudioBus> bufferBus = AudioBus::create(numberOfChannels, bufferLength, false);
    144     for (unsigned i = 0; i < numberOfChannels; ++i)
    145         bufferBus->setChannelMemory(i, buffer->getChannelData(i)->data(), bufferLength);
    146 
    147     bufferBus->setSampleRate(buffer->sampleRate());
    148 
    149     // Create the reverb with the given impulse response.
    150     bool useBackgroundThreads = !context()->isOfflineContext();
    151     OwnPtr<Reverb> reverb = adoptPtr(new Reverb(bufferBus.get(), AudioNode::ProcessingSizeInFrames, MaxFFTSize, 2, useBackgroundThreads, m_normalize));
    152 
    153     {
    154         // Synchronize with process().
    155         MutexLocker locker(m_processLock);
    156         m_reverb = reverb.release();
    157         m_buffer = buffer;
    158     }
    159 }
    160 
    161 AudioBuffer* ConvolverNode::buffer()
    162 {
    163     ASSERT(isMainThread());
    164     return m_buffer.get();
    165 }
    166 
    167 double ConvolverNode::tailTime() const
    168 {
    169     MutexTryLocker tryLocker(m_processLock);
    170     if (tryLocker.locked())
    171         return m_reverb ? m_reverb->impulseResponseLength() / static_cast<double>(sampleRate()) : 0;
    172     // Since we don't want to block the Audio Device thread, we return a large value
    173     // instead of trying to acquire the lock.
    174     return std::numeric_limits<double>::infinity();
    175 }
    176 
    177 double ConvolverNode::latencyTime() const
    178 {
    179     MutexTryLocker tryLocker(m_processLock);
    180     if (tryLocker.locked())
    181         return m_reverb ? m_reverb->latencyFrames() / static_cast<double>(sampleRate()) : 0;
    182     // Since we don't want to block the Audio Device thread, we return a large value
    183     // instead of trying to acquire the lock.
    184     return std::numeric_limits<double>::infinity();
    185 }
    186 
    187 void ConvolverNode::trace(Visitor* visitor)
    188 {
    189     visitor->trace(m_buffer);
    190     AudioNode::trace(visitor);
    191 }
    192 
    193 } // namespace blink
    194 
    195 #endif // ENABLE(WEB_AUDIO)
    196