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 GainNode_h
26#define GainNode_h
27
28#include "modules/webaudio/AudioNode.h"
29#include "modules/webaudio/AudioParam.h"
30#include "wtf/PassRefPtr.h"
31#include "wtf/Threading.h"
32
33namespace blink {
34
35class AudioContext;
36
37// GainNode is an AudioNode with one input and one output which applies a gain (volume) change to the audio signal.
38// De-zippering (smoothing) is applied when the gain value is changed dynamically.
39
40class GainNode FINAL : public AudioNode {
41    DEFINE_WRAPPERTYPEINFO();
42public:
43    static GainNode* create(AudioContext* context, float sampleRate)
44    {
45        return adoptRefCountedGarbageCollectedWillBeNoop(new GainNode(context, sampleRate));
46    }
47
48    // AudioNode
49    virtual void process(size_t framesToProcess) OVERRIDE;
50
51    // Called in the main thread when the number of channels for the input may have changed.
52    virtual void checkNumberOfChannelsForInput(AudioNodeInput*) OVERRIDE;
53
54    // JavaScript interface
55    AudioParam* gain() { return m_gain.get(); }
56
57    virtual void trace(Visitor*) OVERRIDE;
58
59private:
60    virtual double tailTime() const OVERRIDE { return 0; }
61    virtual double latencyTime() const OVERRIDE { return 0; }
62
63    GainNode(AudioContext*, float sampleRate);
64
65    float m_lastGain; // for de-zippering
66    Member<AudioParam> m_gain;
67
68    AudioFloatArray m_sampleAccurateGainValues;
69};
70
71} // namespace blink
72
73#endif // GainNode_h
74