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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  *
      8  * 1.  Redistributions of source code must retain the above copyright
      9  *     notice, this list of conditions and the following disclaimer.
     10  * 2.  Redistributions in binary form must reproduce the above copyright
     11  *     notice, this list of conditions and the following disclaimer in the
     12  *     documentation and/or other materials provided with the distribution.
     13  * 3.  Neither the name of Apple Computer, Inc. ("Apple") nor the names of
     14  *     its contributors may be used to endorse or promote products derived
     15  *     from this software without specific prior written permission.
     16  *
     17  * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
     18  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
     19  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
     20  * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
     21  * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
     22  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
     23  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
     24  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     25  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
     26  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     27  */
     28 
     29 #include "config.h"
     30 
     31 #if ENABLE(WEB_AUDIO)
     32 
     33 #include "modules/webaudio/ChannelMergerNode.h"
     34 
     35 #include "modules/webaudio/AudioContext.h"
     36 #include "modules/webaudio/AudioNodeInput.h"
     37 #include "modules/webaudio/AudioNodeOutput.h"
     38 
     39 const unsigned DefaultNumberOfOutputChannels = 1;
     40 
     41 namespace WebCore {
     42 
     43 PassRefPtr<ChannelMergerNode> ChannelMergerNode::create(AudioContext* context, float sampleRate, unsigned numberOfInputs)
     44 {
     45     if (!numberOfInputs || numberOfInputs > AudioContext::maxNumberOfChannels())
     46         return 0;
     47 
     48     return adoptRef(new ChannelMergerNode(context, sampleRate, numberOfInputs));
     49 }
     50 
     51 ChannelMergerNode::ChannelMergerNode(AudioContext* context, float sampleRate, unsigned numberOfInputs)
     52     : AudioNode(context, sampleRate)
     53     , m_desiredNumberOfOutputChannels(DefaultNumberOfOutputChannels)
     54 {
     55     ScriptWrappable::init(this);
     56     // Create the requested number of inputs.
     57     for (unsigned i = 0; i < numberOfInputs; ++i)
     58         addInput(adoptPtr(new AudioNodeInput(this)));
     59 
     60     addOutput(adoptPtr(new AudioNodeOutput(this, 1)));
     61     setNodeType(NodeTypeChannelMerger);
     62     initialize();
     63 }
     64 
     65 void ChannelMergerNode::process(size_t framesToProcess)
     66 {
     67     AudioNodeOutput* output = this->output(0);
     68     ASSERT(output);
     69     ASSERT_UNUSED(framesToProcess, framesToProcess == output->bus()->length());
     70 
     71     // Output bus not updated yet, so just output silence.
     72     if (m_desiredNumberOfOutputChannels != output->numberOfChannels()) {
     73         output->bus()->zero();
     74         return;
     75     }
     76 
     77     // Merge all the channels from all the inputs into one output.
     78     unsigned outputChannelIndex = 0;
     79     for (unsigned i = 0; i < numberOfInputs(); ++i) {
     80         AudioNodeInput* input = this->input(i);
     81         if (input->isConnected()) {
     82             unsigned numberOfInputChannels = input->bus()->numberOfChannels();
     83 
     84             // Merge channels from this particular input.
     85             for (unsigned j = 0; j < numberOfInputChannels; ++j) {
     86                 AudioChannel* inputChannel = input->bus()->channel(j);
     87                 AudioChannel* outputChannel = output->bus()->channel(outputChannelIndex);
     88                 outputChannel->copyFrom(inputChannel);
     89 
     90                 ++outputChannelIndex;
     91             }
     92         }
     93     }
     94 
     95     ASSERT(outputChannelIndex == output->numberOfChannels());
     96 }
     97 
     98 void ChannelMergerNode::reset()
     99 {
    100 }
    101 
    102 // Any time a connection or disconnection happens on any of our inputs, we potentially need to change the
    103 // number of channels of our output.
    104 void ChannelMergerNode::checkNumberOfChannelsForInput(AudioNodeInput* input)
    105 {
    106     ASSERT(context()->isAudioThread() && context()->isGraphOwner());
    107 
    108     // Count how many channels we have all together from all of the inputs.
    109     unsigned numberOfOutputChannels = 0;
    110     for (unsigned i = 0; i < numberOfInputs(); ++i) {
    111         AudioNodeInput* input = this->input(i);
    112         if (input->isConnected())
    113             numberOfOutputChannels += input->numberOfChannels();
    114     }
    115 
    116     // Set the correct number of channels on the output
    117     AudioNodeOutput* output = this->output(0);
    118     ASSERT(output);
    119     output->setNumberOfChannels(numberOfOutputChannels);
    120     // There can in rare cases be a slight delay before the output bus is updated to the new number of
    121     // channels because of tryLocks() in the context's updating system. So record the new number of
    122     // output channels here.
    123     m_desiredNumberOfOutputChannels = numberOfOutputChannels;
    124 
    125     AudioNode::checkNumberOfChannelsForInput(input);
    126 }
    127 
    128 } // namespace WebCore
    129 
    130 #endif // ENABLE(WEB_AUDIO)
    131