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 "modules/webaudio/GainNode.h"
30
31#include "platform/audio/AudioBus.h"
32#include "modules/webaudio/AudioNodeInput.h"
33#include "modules/webaudio/AudioNodeOutput.h"
34
35namespace blink {
36
37GainNode::GainNode(AudioContext* context, float sampleRate)
38    : AudioNode(context, sampleRate)
39    , m_lastGain(1.0)
40    , m_sampleAccurateGainValues(AudioNode::ProcessingSizeInFrames) // FIXME: can probably share temp buffer in context
41{
42    m_gain = AudioParam::create(context, 1.0);
43
44    addInput();
45    addOutput(AudioNodeOutput::create(this, 1));
46
47    setNodeType(NodeTypeGain);
48
49    initialize();
50}
51
52void GainNode::process(size_t framesToProcess)
53{
54    // FIXME: for some cases there is a nice optimization to avoid processing here, and let the gain change
55    // happen in the summing junction input of the AudioNode we're connected to.
56    // Then we can avoid all of the following:
57
58    AudioBus* outputBus = output(0)->bus();
59    ASSERT(outputBus);
60
61    if (!isInitialized() || !input(0)->isConnected())
62        outputBus->zero();
63    else {
64        AudioBus* inputBus = input(0)->bus();
65
66        if (gain()->hasSampleAccurateValues()) {
67            // Apply sample-accurate gain scaling for precise envelopes, grain windows, etc.
68            ASSERT(framesToProcess <= m_sampleAccurateGainValues.size());
69            if (framesToProcess <= m_sampleAccurateGainValues.size()) {
70                float* gainValues = m_sampleAccurateGainValues.data();
71                gain()->calculateSampleAccurateValues(gainValues, framesToProcess);
72                outputBus->copyWithSampleAccurateGainValuesFrom(*inputBus, gainValues, framesToProcess);
73            }
74        } else {
75            // Apply the gain with de-zippering into the output bus.
76            outputBus->copyWithGainFrom(*inputBus, &m_lastGain, gain()->value());
77        }
78    }
79}
80
81// FIXME: this can go away when we do mixing with gain directly in summing junction of AudioNodeInput
82//
83// As soon as we know the channel count of our input, we can lazily initialize.
84// Sometimes this may be called more than once with different channel counts, in which case we must safely
85// uninitialize and then re-initialize with the new channel count.
86void GainNode::checkNumberOfChannelsForInput(AudioNodeInput* input)
87{
88    ASSERT(context()->isAudioThread() && context()->isGraphOwner());
89
90    ASSERT(input && input == this->input(0));
91    if (input != this->input(0))
92        return;
93
94    unsigned numberOfChannels = input->numberOfChannels();
95
96    if (isInitialized() && numberOfChannels != output(0)->numberOfChannels()) {
97        // We're already initialized but the channel count has changed.
98        uninitialize();
99    }
100
101    if (!isInitialized()) {
102        // This will propagate the channel count to any nodes connected further downstream in the graph.
103        output(0)->setNumberOfChannels(numberOfChannels);
104        initialize();
105    }
106
107    AudioNode::checkNumberOfChannelsForInput(input);
108}
109
110void GainNode::trace(Visitor* visitor)
111{
112    visitor->trace(m_gain);
113    AudioNode::trace(visitor);
114}
115
116} // namespace blink
117
118#endif // ENABLE(WEB_AUDIO)
119