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