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 Computer, 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 "wtf/OwnPtr.h" 33 #include "wtf/PassOwnPtr.h" 34 #include "wtf/text/WTFString.h" 35 36 namespace WebCore { 37 38 class AudioIOCallback; 39 40 // AudioDestination is an abstraction for audio hardware I/O. 41 // The audio hardware periodically calls the AudioIOCallback render() method asking it to render/output the next render quantum of audio. 42 // It optionally will pass in local/live audio input when it calls render(). 43 44 class AudioDestination { 45 public: 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 PassOwnPtr<AudioDestination> create(AudioIOCallback&, const String& inputDeviceId, unsigned numberOfInputChannels, unsigned numberOfOutputChannels, float sampleRate); 49 50 virtual ~AudioDestination() { } 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
