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 "GainNode.h"
30
31#include "AudioBus.h"
32#include "AudioNodeInput.h"
33#include "AudioNodeOutput.h"
34#include <wtf/IsoMallocInlines.h>
35
36namespace WebCore {
37
38WTF_MAKE_ISO_ALLOCATED_IMPL(GainNode);
39
40GainNode::GainNode(AudioContext& context, float sampleRate)
41 : AudioNode(context, sampleRate)
42 , m_lastGain(1.0)
43 , m_sampleAccurateGainValues(AudioNode::ProcessingSizeInFrames) // FIXME: can probably share temp buffer in context
44{
45 setNodeType(NodeTypeGain);
46
47 m_gain = AudioParam::create(context, "gain", 1.0, 0.0, 1.0);
48
49 addInput(std::make_unique<AudioNodeInput>(this));
50 addOutput(std::make_unique<AudioNodeOutput>(this, 1));
51
52 initialize();
53}
54
55void GainNode::process(size_t framesToProcess)
56{
57 // FIXME: for some cases there is a nice optimization to avoid processing here, and let the gain change
58 // happen in the summing junction input of the AudioNode we're connected to.
59 // Then we can avoid all of the following:
60
61 AudioBus* outputBus = output(0)->bus();
62 ASSERT(outputBus);
63
64 if (!isInitialized() || !input(0)->isConnected())
65 outputBus->zero();
66 else {
67 AudioBus* inputBus = input(0)->bus();
68
69 if (gain()->hasSampleAccurateValues()) {
70 // Apply sample-accurate gain scaling for precise envelopes, grain windows, etc.
71 ASSERT(framesToProcess <= m_sampleAccurateGainValues.size());
72 if (framesToProcess <= m_sampleAccurateGainValues.size()) {
73 float* gainValues = m_sampleAccurateGainValues.data();
74 gain()->calculateSampleAccurateValues(gainValues, framesToProcess);
75 outputBus->copyWithSampleAccurateGainValuesFrom(*inputBus, gainValues, framesToProcess);
76 }
77 } else {
78 // Apply the gain with de-zippering into the output bus.
79 if (!m_lastGain && m_lastGain == m_gain->value()) {
80 // If the gain is 0 (and we've converged on dezippering), just zero the bus and set
81 // the silence hint.
82 outputBus->zero();
83 } else
84 outputBus->copyWithGainFrom(*inputBus, &m_lastGain, gain()->value());
85 }
86 }
87}
88
89void GainNode::reset()
90{
91 // Snap directly to desired gain.
92 m_lastGain = gain()->value();
93}
94
95// FIXME: this can go away when we do mixing with gain directly in summing junction of AudioNodeInput
96//
97// As soon as we know the channel count of our input, we can lazily initialize.
98// Sometimes this may be called more than once with different channel counts, in which case we must safely
99// uninitialize and then re-initialize with the new channel count.
100void GainNode::checkNumberOfChannelsForInput(AudioNodeInput* input)
101{
102 ASSERT(context().isAudioThread() && context().isGraphOwner());
103
104 ASSERT(input && input == this->input(0));
105 if (input != this->input(0))
106 return;
107
108 unsigned numberOfChannels = input->numberOfChannels();
109
110 if (isInitialized() && numberOfChannels != output(0)->numberOfChannels()) {
111 // We're already initialized but the channel count has changed.
112 uninitialize();
113 }
114
115 if (!isInitialized()) {
116 // This will propagate the channel count to any nodes connected further downstream in the graph.
117 output(0)->setNumberOfChannels(numberOfChannels);
118 initialize();
119 }
120
121 AudioNode::checkNumberOfChannelsForInput(input);
122}
123
124} // namespace WebCore
125
126#endif // ENABLE(WEB_AUDIO)
127