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 *
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 * 3. Neither the name of Apple Inc. ("Apple") nor the names of
14 * its contributors may be used to endorse or promote products derived
15 * from this software without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
18 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
19 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
20 * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
21 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
22 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
23 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
24 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 */
28
29#ifndef AudioDestination_h
30#define AudioDestination_h
31
32#include <memory>
33#include <wtf/text/WTFString.h>
34
35namespace WebCore {
36
37class AudioIOCallback;
38
39// AudioDestination is an abstraction for audio hardware I/O.
40// The audio hardware periodically calls the AudioIOCallback render() method asking it to render/output the next render quantum of audio.
41// It optionally will pass in local/live audio input when it calls render().
42
43class AudioDestination {
44 WTF_MAKE_FAST_ALLOCATED;
45public:
46 // Pass in (numberOfInputChannels > 0) if live/local audio input is desired.
47 // Port-specific device identification information for live/local input streams can be passed in the inputDeviceId.
48 static std::unique_ptr<AudioDestination> create(AudioIOCallback&, const String& inputDeviceId, unsigned numberOfInputChannels, unsigned numberOfOutputChannels, float sampleRate);
49
50 virtual ~AudioDestination() = default;
51
52 virtual void start() = 0;
53 virtual void stop() = 0;
54 virtual bool isPlaying() = 0;
55
56 // Sample-rate conversion may happen in AudioDestination to the hardware sample-rate
57 virtual float sampleRate() const = 0;
58 static float hardwareSampleRate();
59
60 // maxChannelCount() returns the total number of output channels of the audio hardware.
61 // A value of 0 indicates that the number of channels cannot be configured and
62 // that only stereo (2-channel) destinations can be created.
63 // The numberOfOutputChannels parameter of AudioDestination::create() is allowed to
64 // be a value: 1 <= numberOfOutputChannels <= maxChannelCount(),
65 // or if maxChannelCount() equals 0, then numberOfOutputChannels must be 2.
66 static unsigned long maxChannelCount();
67};
68
69} // namespace WebCore
70
71#endif // AudioDestination_h
72