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/*
* Copyright 2017 The Chromium Authors. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 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
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
* ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#pragma once
#include <wtf/Forward.h>
#include <wtf/Noncopyable.h>
#include <wtf/RefPtr.h>
namespace WebCore {
class AudioBus;
// PushPullFIFO class is an intermediate audio sample storage between
// WebKit-WebAudio and the renderer. The renderer's hardware callback buffer size
// varies on the platform, but the WebAudio always renders 128 frames (render
// quantum, RQ) thus FIFO is needed to handle the general case.
class PushPullFIFO {
WTF_MAKE_NONCOPYABLE(PushPullFIFO);
public:
// Maximum FIFO length. (512 render quanta)
static constexpr size_t maxFIFOLength { 65536 };
// |fifoLength| cannot exceed |maxFIFOLength|. Otherwise it crashes.
WEBCORE_EXPORT PushPullFIFO(unsigned numberOfChannels, size_t fifoLength);
WEBCORE_EXPORT ~PushPullFIFO();
// Pushes the rendered frames by WebAudio engine.
// - The |inputBus| length is 128 frames (1 render quantum), fixed.
// - In case of overflow (FIFO full while push), the existing frames in FIFO
// will be overwritten and |indexRead| will be forcibly moved to
// |indexWrite| to avoid reading overwritten frames.
WEBCORE_EXPORT void push(const AudioBus* inputBus);
// Pulls |framesRequested| by the audio device thread and returns the actual
// number of frames to be rendered by the source. (i.e. WebAudio graph)
WEBCORE_EXPORT size_t pull(AudioBus* outputBus, size_t framesRequested);
size_t framesAvailable() const { return m_framesAvailable; }
size_t length() const { return m_fifoLength; }
unsigned numberOfChannels() const;
AudioBus* bus() const { return m_fifoBus.get(); }
private:
// The size of the FIFO.
const size_t m_fifoLength = 0;
RefPtr<AudioBus> m_fifoBus;
// The number of frames in the FIFO actually available for pulling.
size_t m_framesAvailable { 0 };
size_t m_indexRead { 0 };
size_t m_indexWrite { 0 };
};
} // namespace WebCore
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