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 blink {
42
43ChannelMergerNode* ChannelMergerNode::create(AudioContext* context, float sampleRate, unsigned numberOfInputs)
44{
45    if (!numberOfInputs || numberOfInputs > AudioContext::maxNumberOfChannels())
46        return 0;
47
48    return adoptRefCountedGarbageCollectedWillBeNoop(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    // Create the requested number of inputs.
56    for (unsigned i = 0; i < numberOfInputs; ++i)
57        addInput();
58
59    addOutput(AudioNodeOutput::create(this, 1));
60    setNodeType(NodeTypeChannelMerger);
61    initialize();
62}
63
64void ChannelMergerNode::process(size_t framesToProcess)
65{
66    AudioNodeOutput* output = this->output(0);
67    ASSERT(output);
68    ASSERT_UNUSED(framesToProcess, framesToProcess == output->bus()->length());
69
70    // Output bus not updated yet, so just output silence.
71    if (m_desiredNumberOfOutputChannels != output->numberOfChannels()) {
72        output->bus()->zero();
73        return;
74    }
75
76    // Merge all the channels from all the inputs into one output.
77    unsigned outputChannelIndex = 0;
78    unsigned maxAllowedOutputChannels = output->numberOfChannels();
79
80    for (unsigned i = 0; i < numberOfInputs(); ++i) {
81        AudioNodeInput* input = this->input(i);
82        if (input->isConnected()) {
83            unsigned numberOfInputChannels = input->bus()->numberOfChannels();
84
85            // Merge channels from this particular input, but be careful not to exceed the number of
86            // output channels.  (This can happen if there are many inputs with each input
87            // containing many channels.)
88            for (unsigned j = 0; j < numberOfInputChannels; ++j) {
89                if (outputChannelIndex < maxAllowedOutputChannels) {
90                    AudioChannel* inputChannel = input->bus()->channel(j);
91                    AudioChannel* outputChannel = output->bus()->channel(outputChannelIndex);
92                    outputChannel->copyFrom(inputChannel);
93
94                    ++outputChannelIndex;
95                }
96            }
97        }
98        if (outputChannelIndex >= maxAllowedOutputChannels)
99            break;
100    }
101
102    ASSERT(outputChannelIndex == output->numberOfChannels());
103}
104
105// Any time a connection or disconnection happens on any of our inputs, we potentially need to change the
106// number of channels of our output.
107void ChannelMergerNode::checkNumberOfChannelsForInput(AudioNodeInput* input)
108{
109    ASSERT(context()->isAudioThread() && context()->isGraphOwner());
110
111    // Count how many channels we have all together from all of the inputs.
112    unsigned numberOfOutputChannels = 0;
113    for (unsigned i = 0; i < numberOfInputs(); ++i) {
114        AudioNodeInput* input = this->input(i);
115        if (input->isConnected())
116            numberOfOutputChannels += input->numberOfChannels();
117    }
118
119    // If the actual number of channels exceeds the max allowed, just drop the excess.
120    numberOfOutputChannels = std::min(numberOfOutputChannels, AudioContext::maxNumberOfChannels());
121
122    // Set the correct number of channels on the output
123    AudioNodeOutput* output = this->output(0);
124    ASSERT(output);
125    output->setNumberOfChannels(numberOfOutputChannels);
126    // There can in rare cases be a slight delay before the output bus is updated to the new number of
127    // channels because of tryLocks() in the context's updating system. So record the new number of
128    // output channels here.
129    m_desiredNumberOfOutputChannels = numberOfOutputChannels;
130
131    AudioNode::checkNumberOfChannelsForInput(input);
132}
133
134} // namespace blink
135
136#endif // ENABLE(WEB_AUDIO)
137