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