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      1 /*
      2  * Copyright (C) 2012, 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/MediaStreamAudioSourceNode.h"
     30 
     31 #include "platform/Logging.h"
     32 #include "modules/webaudio/AudioContext.h"
     33 #include "modules/webaudio/AudioNodeOutput.h"
     34 #include "wtf/Locker.h"
     35 
     36 namespace blink {
     37 
     38 MediaStreamAudioSourceNode* MediaStreamAudioSourceNode::create(AudioContext* context, MediaStream* mediaStream, MediaStreamTrack* audioTrack, PassOwnPtr<AudioSourceProvider> audioSourceProvider)
     39 {
     40     return adoptRefCountedGarbageCollectedWillBeNoop(new MediaStreamAudioSourceNode(context, mediaStream, audioTrack, audioSourceProvider));
     41 }
     42 
     43 MediaStreamAudioSourceNode::MediaStreamAudioSourceNode(AudioContext* context, MediaStream* mediaStream, MediaStreamTrack* audioTrack, PassOwnPtr<AudioSourceProvider> audioSourceProvider)
     44     : AudioSourceNode(context, context->sampleRate())
     45     , m_mediaStream(mediaStream)
     46     , m_audioTrack(audioTrack)
     47     , m_audioSourceProvider(audioSourceProvider)
     48     , m_sourceNumberOfChannels(0)
     49 {
     50     // Default to stereo. This could change depending on the format of the
     51     // MediaStream's audio track.
     52     addOutput(AudioNodeOutput::create(this, 2));
     53 
     54     setNodeType(NodeTypeMediaStreamAudioSource);
     55 
     56     initialize();
     57 }
     58 
     59 MediaStreamAudioSourceNode::~MediaStreamAudioSourceNode()
     60 {
     61     ASSERT(!isInitialized());
     62 }
     63 
     64 void MediaStreamAudioSourceNode::dispose()
     65 {
     66     uninitialize();
     67     AudioSourceNode::dispose();
     68 }
     69 
     70 void MediaStreamAudioSourceNode::setFormat(size_t numberOfChannels, float sourceSampleRate)
     71 {
     72     if (numberOfChannels != m_sourceNumberOfChannels || sourceSampleRate != sampleRate()) {
     73         // The sample-rate must be equal to the context's sample-rate.
     74         if (!numberOfChannels || numberOfChannels > AudioContext::maxNumberOfChannels() || sourceSampleRate != sampleRate()) {
     75             // process() will generate silence for these uninitialized values.
     76             WTF_LOG(Media, "MediaStreamAudioSourceNode::setFormat(%u, %f) - unhandled format change", static_cast<unsigned>(numberOfChannels), sourceSampleRate);
     77             m_sourceNumberOfChannels = 0;
     78             return;
     79         }
     80 
     81         // Synchronize with process().
     82         MutexLocker locker(m_processLock);
     83 
     84         m_sourceNumberOfChannels = numberOfChannels;
     85 
     86         {
     87             // The context must be locked when changing the number of output channels.
     88             AudioContext::AutoLocker contextLocker(context());
     89 
     90             // Do any necesssary re-configuration to the output's number of channels.
     91             output(0)->setNumberOfChannels(numberOfChannels);
     92         }
     93     }
     94 }
     95 
     96 void MediaStreamAudioSourceNode::process(size_t numberOfFrames)
     97 {
     98     AudioBus* outputBus = output(0)->bus();
     99 
    100     if (!audioSourceProvider()) {
    101         outputBus->zero();
    102         return;
    103     }
    104 
    105     if (!mediaStream() || m_sourceNumberOfChannels != outputBus->numberOfChannels()) {
    106         outputBus->zero();
    107         return;
    108     }
    109 
    110     // Use a tryLock() to avoid contention in the real-time audio thread.
    111     // If we fail to acquire the lock then the MediaStream must be in the middle of
    112     // a format change, so we output silence in this case.
    113     MutexTryLocker tryLocker(m_processLock);
    114     if (tryLocker.locked())
    115         audioSourceProvider()->provideInput(outputBus, numberOfFrames);
    116     else {
    117         // We failed to acquire the lock.
    118         outputBus->zero();
    119     }
    120 }
    121 
    122 void MediaStreamAudioSourceNode::trace(Visitor* visitor)
    123 {
    124     visitor->trace(m_mediaStream);
    125     visitor->trace(m_audioTrack);
    126     AudioSourceNode::trace(visitor);
    127     AudioSourceProviderClient::trace(visitor);
    128 }
    129 
    130 } // namespace blink
    131 
    132 #endif // ENABLE(WEB_AUDIO)
    133