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