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/*
* Copyright (C) 2010 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 AudioDestination_h
#define AudioDestination_h
#include "platform/PlatformExport.h"
#include "wtf/OwnPtr.h"
#include "wtf/PassOwnPtr.h"
#include "wtf/text/WTFString.h"
namespace WebCore {
class AudioIOCallback;
// AudioDestination is an abstraction for audio hardware I/O.
// The audio hardware periodically calls the AudioIOCallback render() method asking it to render/output the next render quantum of audio.
// It optionally will pass in local/live audio input when it calls render().
class PLATFORM_EXPORT AudioDestination {
public:
// Pass in (numberOfInputChannels > 0) if live/local audio input is desired.
// Port-specific device identification information for live/local input streams can be passed in the inputDeviceId.
static PassOwnPtr<AudioDestination> create(AudioIOCallback&, const String& inputDeviceId, unsigned numberOfInputChannels, unsigned numberOfOutputChannels, float sampleRate);
virtual ~AudioDestination() { }
virtual void start() = 0;
virtual void stop() = 0;
virtual bool isPlaying() = 0;
// Sample-rate conversion may happen in AudioDestination to the hardware sample-rate
virtual float sampleRate() const = 0;
static float hardwareSampleRate();
// maxChannelCount() returns the total number of output channels of the audio hardware.
// A value of 0 indicates that the number of channels cannot be configured and
// that only stereo (2-channel) destinations can be created.
// The numberOfOutputChannels parameter of AudioDestination::create() is allowed to
// be a value: 1 <= numberOfOutputChannels <= maxChannelCount(),
// or if maxChannelCount() equals 0, then numberOfOutputChannels must be 2.
static unsigned long maxChannelCount();
};
} // namespace WebCore
#endif // AudioDestination_h