Source/WebCore/Modules/webaudio/AudioBuffer.h

/*
 * Copyright (C) 2010 Google Inc. All rights reserved.
 * Copyright (C) 2017 Apple Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
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 * 1.  Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 * 2.  Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
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 *     its contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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#pragma once

#include "ExceptionOr.h"
#include <JavaScriptCore/Float32Array.h>
#include <wtf/Lock.h>
#include <wtf/Vector.h>

namespace WebCore {

class AudioBus;

class AudioBuffer : public RefCounted<AudioBuffer> {
public:   
    static RefPtr<AudioBuffer> create(unsigned numberOfChannels, size_t numberOfFrames, float sampleRate);

    // Returns nullptr if data is not a valid audio file.
    static RefPtr<AudioBuffer> createFromAudioFileData(const void* data, size_t dataSize, bool mixToMono, float sampleRate);

    // Format
    size_t length() const { return m_length; }
    double duration() const { return length() / sampleRate(); }
    float sampleRate() const { return m_sampleRate; }

    // Channel data access
    unsigned numberOfChannels() const { return m_channels.size(); }
    ExceptionOr<Ref<Float32Array>> getChannelData(unsigned channelIndex);
    Float32Array* channelData(unsigned channelIndex);
    void zero();

    // Scalar gain
    double gain() const { return m_gain; }
    void setGain(double gain) { m_gain = gain; }

    // Because an AudioBuffer has a JavaScript wrapper, which will be garbage collected, it may take a while for this object to be deleted.
    // releaseMemory() can be called when the AudioContext goes away, so we can release the memory earlier than when the garbage collection happens.
    // Careful! Only call this when the page unloads, after the AudioContext is no longer processing.
    void releaseMemory();

    size_t memoryCost() const;
    
private:
    AudioBuffer(unsigned numberOfChannels, size_t numberOfFrames, float sampleRate);
    explicit AudioBuffer(AudioBus&);

    void invalidate();

    double m_gain { 1.0 }; // scalar gain
    float m_sampleRate;
    mutable Lock m_channelsLock;
    size_t m_length;
    Vector<RefPtr<Float32Array>> m_channels;
};

} // namespace WebCore