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#ifndef ScriptProcessorNode_h
26#define ScriptProcessorNode_h
27
28#include "platform/audio/AudioBus.h"
29#include "modules/webaudio/AudioNode.h"
30#include "wtf/Forward.h"
31#include "wtf/PassRefPtr.h"
32#include "wtf/RefPtr.h"
33#include "wtf/Vector.h"
34
35namespace blink {
36
37class AudioBuffer;
38class AudioContext;
39class AudioProcessingEvent;
40
41// ScriptProcessorNode is an AudioNode which allows for arbitrary synthesis or processing directly using JavaScript.
42// The API allows for a variable number of inputs and outputs, although it must have at least one input or output.
43// This basic implementation supports no more than one input and output.
44// The "onaudioprocess" attribute is an event listener which will get called periodically with an AudioProcessingEvent which has
45// AudioBuffers for each input and output.
46
47class ScriptProcessorNode FINAL : public AudioNode {
48    DEFINE_WRAPPERTYPEINFO();
49public:
50    // bufferSize must be one of the following values: 256, 512, 1024, 2048, 4096, 8192, 16384.
51    // This value controls how frequently the onaudioprocess event handler is called and how many sample-frames need to be processed each call.
52    // Lower numbers for bufferSize will result in a lower (better) latency. Higher numbers will be necessary to avoid audio breakup and glitches.
53    // The value chosen must carefully balance between latency and audio quality.
54    static ScriptProcessorNode* create(AudioContext*, float sampleRate, size_t bufferSize, unsigned numberOfInputChannels, unsigned numberOfOutputChannels);
55
56    virtual ~ScriptProcessorNode();
57
58    // AudioNode
59    virtual void dispose() OVERRIDE;
60    virtual void process(size_t framesToProcess) OVERRIDE;
61    virtual void initialize() OVERRIDE;
62    virtual void uninitialize() OVERRIDE;
63
64    size_t bufferSize() const { return m_bufferSize; }
65
66    DEFINE_ATTRIBUTE_EVENT_LISTENER(audioprocess);
67
68    void trace(Visitor*);
69
70private:
71    virtual double tailTime() const OVERRIDE;
72    virtual double latencyTime() const OVERRIDE;
73
74    ScriptProcessorNode(AudioContext*, float sampleRate, size_t bufferSize, unsigned numberOfInputChannels, unsigned numberOfOutputChannels);
75
76    void fireProcessEvent();
77
78    // Double buffering
79    unsigned doubleBufferIndex() const { return m_doubleBufferIndex; }
80    void swapBuffers() { m_doubleBufferIndex = 1 - m_doubleBufferIndex; }
81    unsigned m_doubleBufferIndex;
82    unsigned m_doubleBufferIndexForEvent;
83    HeapVector<Member<AudioBuffer> > m_inputBuffers;
84    HeapVector<Member<AudioBuffer> > m_outputBuffers;
85
86    size_t m_bufferSize;
87    unsigned m_bufferReadWriteIndex;
88
89    unsigned m_numberOfInputChannels;
90    unsigned m_numberOfOutputChannels;
91
92    RefPtr<AudioBus> m_internalInputBus;
93    // Synchronize process() with fireProcessEvent().
94    mutable Mutex m_processEventLock;
95};
96
97} // namespace blink
98
99#endif // ScriptProcessorNode_h
100