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/*
* Copyright (C) 2012 Google 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:
*
* 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.
* 3. Neither the name of Apple Computer, Inc. ("Apple") nor the names of
* 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
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL APPLE 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.
*/
#ifndef AudioPullFIFO_h
#define AudioPullFIFO_h
#include "platform/audio/AudioBus.h"
#include "platform/audio/AudioFIFO.h"
#include "platform/audio/AudioSourceProvider.h"
#include "wtf/Allocator.h"
namespace blink {
// A FIFO (First In First Out) buffer to handle mismatches in buffer sizes
// between a provider and receiver. The receiver will "pull" data from this
// FIFO. If data is already available in the FIFO, it is provided to the
// receiver. If insufficient data is available to satisfy the request, the FIFO
// will ask the provider for more data when necessary to fulfill a request.
// Contrast this with a "push" FIFO, where the sender pushes data to the FIFO
// which will itself push the data to the receiver when the FIFO is full.
class PLATFORM_EXPORT AudioPullFIFO {
USING_FAST_MALLOC(AudioPullFIFO);
WTF_MAKE_NONCOPYABLE(AudioPullFIFO);
public:
// Create a FIFO that gets data from |provider|. The FIFO will be large
// enough to hold |fifoLength| frames of data of |numberOfChannels| channels.
// The AudioSourceProvider will be asked to produce |providerSize| frames
// when the FIFO needs more data.
AudioPullFIFO(AudioSourceProvider& audioProvider,
unsigned numberOfChannels,
size_t fifoLength,
size_t providerSize);
// Read |framesToConsume| frames from the FIFO into the destination. If the
// FIFO does not have enough data, we ask the |provider| to get more data to
// fulfill the request.
void consume(AudioBus* destination, size_t framesToConsume);
private:
// Fill the FIFO buffer with at least |numberOfFrames| more data.
void fillBuffer(size_t numberOfFrames);
// The provider of the data in our FIFO.
AudioSourceProvider& m_provider;
// The actual FIFO
AudioFIFO m_fifo;
// Number of frames of data that the provider will produce per call.
unsigned m_providerSize;
// Temporary workspace to hold the data from the provider.
RefPtr<AudioBus> m_tempBus;
};
} // namespace blink
#endif // AudioPullFIFO.h
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