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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 "AudioChannelSplitter.h"
     30 
     31 #include "AudioNodeInput.h"
     32 #include "AudioNodeOutput.h"
     33 
     34 namespace WebCore {
     35 
     36 // This is considering that 5.1 (6 channels) is the largest we'll ever deal with.
     37 // It can easily be increased to support more if the web audio specification is updated.
     38 const unsigned NumberOfOutputs = 6;
     39 
     40 AudioChannelSplitter::AudioChannelSplitter(AudioContext* context, double sampleRate)
     41     : AudioNode(context, sampleRate)
     42 {
     43     addInput(adoptPtr(new AudioNodeInput(this)));
     44 
     45     // Create a fixed number of outputs (able to handle the maximum number of channels fed to an input).
     46     for (unsigned i = 0; i < NumberOfOutputs; ++i)
     47         addOutput(adoptPtr(new AudioNodeOutput(this, 1)));
     48 
     49     setType(NodeTypeChannelSplitter);
     50 
     51     initialize();
     52 }
     53 
     54 void AudioChannelSplitter::process(size_t framesToProcess)
     55 {
     56     AudioBus* source = input(0)->bus();
     57     ASSERT(source);
     58     ASSERT_UNUSED(framesToProcess, framesToProcess == source->length());
     59 
     60     unsigned numberOfSourceChannels = source->numberOfChannels();
     61 
     62     ASSERT(numberOfOutputs() == NumberOfOutputs);
     63     for (unsigned i = 0; i < NumberOfOutputs; ++i) {
     64         AudioBus* destination = output(i)->bus();
     65         ASSERT(destination);
     66 
     67         if (i < numberOfSourceChannels) {
     68             // Split the channel out if it exists in the source.
     69             // It would be nice to avoid the copy and simply pass along pointers, but this becomes extremely difficult with fanout and fanin.
     70             destination->channel(0)->copyFrom(source->channel(i));
     71         } else if (output(i)->renderingFanOutCount() > 0) {
     72             // Only bother zeroing out the destination if it's connected to anything
     73             destination->zero();
     74         }
     75     }
     76 }
     77 
     78 void AudioChannelSplitter::reset()
     79 {
     80 }
     81 
     82 } // namespace WebCore
     83 
     84 #endif // ENABLE(WEB_AUDIO)
     85