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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 "AudioChannelMerger.h"
     34 
     35 #include "AudioNodeInput.h"
     36 #include "AudioNodeOutput.h"
     37 
     38 namespace WebCore {
     39 
     40 // This is considering that 5.1 (6 channels) is the largest we'll ever deal with.
     41 // It can easily be increased to support more if the web audio specification is updated.
     42 const unsigned NumberOfInputs = 6;
     43 
     44 AudioChannelMerger::AudioChannelMerger(AudioContext* context, double sampleRate)
     45     : AudioNode(context, sampleRate)
     46 {
     47     // Create a fixed number of inputs (able to handle the maximum number of channels we deal with).
     48     for (unsigned i = 0; i < NumberOfInputs; ++i)
     49         addInput(adoptPtr(new AudioNodeInput(this)));
     50 
     51     addOutput(adoptPtr(new AudioNodeOutput(this, 1)));
     52 
     53     setType(NodeTypeChannelMerger);
     54 
     55     initialize();
     56 }
     57 
     58 void AudioChannelMerger::process(size_t framesToProcess)
     59 {
     60     AudioNodeOutput* output = this->output(0);
     61     ASSERT(output);
     62     ASSERT_UNUSED(framesToProcess, framesToProcess == output->bus()->length());
     63 
     64     // Count how many channels we have all together from all of the inputs.
     65     unsigned numberOfOutputChannels = 0;
     66     for (unsigned i = 0; i < numberOfInputs(); ++i) {
     67         AudioNodeInput* input = this->input(i);
     68         if (input->isConnected())
     69             numberOfOutputChannels += input->bus()->numberOfChannels();
     70     }
     71 
     72     // Set the correct number of channels on the output
     73     output->setNumberOfChannels(numberOfOutputChannels);
     74 
     75     // Now merge the channels back into one output.
     76     unsigned outputChannelIndex = 0;
     77     for (unsigned i = 0; i < numberOfInputs(); ++i) {
     78         AudioNodeInput* input = this->input(i);
     79         if (input->isConnected()) {
     80             unsigned numberOfInputChannels = input->bus()->numberOfChannels();
     81 
     82             // Merge channels from this particular input.
     83             for (unsigned j = 0; j < numberOfInputChannels; ++j) {
     84                 AudioChannel* inputChannel = input->bus()->channel(j);
     85                 AudioChannel* outputChannel = output->bus()->channel(outputChannelIndex);
     86                 outputChannel->copyFrom(inputChannel);
     87 
     88                 ++outputChannelIndex;
     89             }
     90         }
     91     }
     92 
     93     ASSERT(outputChannelIndex == numberOfOutputChannels);
     94 }
     95 
     96 void AudioChannelMerger::reset()
     97 {
     98 }
     99 
    100 } // namespace WebCore
    101 
    102 #endif // ENABLE(WEB_AUDIO)
    103