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
39const unsigned DefaultNumberOfOutputChannels = 1;
40
41namespace WebCore {
42
43PassRefPtr<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
51ChannelMergerNode::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
65void 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
98void 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.
104void 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