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 blink {
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 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
process(size_t framesToProcess)52 void 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.
checkNumberOfChannelsForInput(AudioNodeInput * input)86 void 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
trace(Visitor * visitor)110 void 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