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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 #include "config.h"
30 
31 #if ENABLE(WEB_AUDIO)
32 
33 #include "AudioDestinationChromium.h"
34 
35 #include "AudioSourceProvider.h"
36 #include "WebKit.h"
37 #include "WebKitClient.h"
38 
39 using namespace WebKit;
40 
41 namespace WebCore {
42 
43 // Buffer size that the Chromium audio system will call us back with.
44 #if OS(DARWIN)
45 // For Mac OS X the chromium audio backend uses a low-latency CoreAudio API, so a low buffer size is possible.
46 const unsigned callbackBufferSize = 128;
47 #else
48 // This value may need to be tuned based on the OS.
49 // FIXME: It may be possible to reduce this value once real-time threads
50 // and other Chromium audio improvements are made.
51 const unsigned callbackBufferSize = 2048;
52 #endif
53 
54 // Buffer size at which the web audio engine will render.
55 const unsigned renderBufferSize = 128;
56 
57 const unsigned renderCountPerCallback = callbackBufferSize / renderBufferSize;
58 
59 // FIXME: add support for multi-channel.
60 const unsigned numberOfChannels = 2;
61 
62 // Factory method: Chromium-implementation
create(AudioSourceProvider & provider,double sampleRate)63 PassOwnPtr<AudioDestination> AudioDestination::create(AudioSourceProvider& provider, double sampleRate)
64 {
65     return adoptPtr(new AudioDestinationChromium(provider, sampleRate));
66 }
67 
AudioDestinationChromium(AudioSourceProvider & provider,double sampleRate)68 AudioDestinationChromium::AudioDestinationChromium(AudioSourceProvider& provider, double sampleRate)
69     : m_provider(provider)
70     , m_renderBus(numberOfChannels, renderBufferSize, false)
71     , m_sampleRate(sampleRate)
72     , m_isPlaying(false)
73 {
74     m_audioDevice = adoptPtr(webKitClient()->createAudioDevice(callbackBufferSize, numberOfChannels, sampleRate, this));
75     ASSERT(m_audioDevice.get());
76 }
77 
~AudioDestinationChromium()78 AudioDestinationChromium::~AudioDestinationChromium()
79 {
80     stop();
81 }
82 
start()83 void AudioDestinationChromium::start()
84 {
85     if (!m_isPlaying && m_audioDevice.get()) {
86         m_audioDevice->start();
87         m_isPlaying = true;
88     }
89 }
90 
stop()91 void AudioDestinationChromium::stop()
92 {
93     if (m_isPlaying && m_audioDevice.get()) {
94         m_audioDevice->stop();
95         m_isPlaying = false;
96     }
97 }
98 
hardwareSampleRate()99 double AudioDestination::hardwareSampleRate()
100 {
101     return webKitClient()->audioHardwareSampleRate();
102 }
103 
104 // Pulls on our provider to get the rendered audio stream.
render(const WebVector<float * > & audioData,size_t numberOfFrames)105 void AudioDestinationChromium::render(const WebVector<float*>& audioData, size_t numberOfFrames)
106 {
107     bool isNumberOfChannelsGood = audioData.size() == numberOfChannels;
108     if (!isNumberOfChannelsGood) {
109         ASSERT_NOT_REACHED();
110         return;
111     }
112 
113     bool isBufferSizeGood = numberOfFrames == callbackBufferSize;
114     if (!isBufferSizeGood) {
115         ASSERT_NOT_REACHED();
116         return;
117     }
118 
119     // Split up the callback buffer into smaller chunks which we'll render one after the other.
120     for (unsigned i = 0; i < renderCountPerCallback; ++i) {
121         m_renderBus.setChannelMemory(0, audioData[0] + i * renderBufferSize, renderBufferSize);
122         m_renderBus.setChannelMemory(1, audioData[1] + i * renderBufferSize, renderBufferSize);
123         m_provider.provideInput(&m_renderBus, renderBufferSize);
124     }
125 }
126 
127 } // namespace WebCore
128 
129 #endif // ENABLE(WEB_AUDIO)
130