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1 /* | |
2 * Copyright (C) 2012 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 AudioPullFIFO_h | |
30 #define AudioPullFIFO_h | |
31 | |
32 #include "platform/audio/AudioBus.h" | |
33 #include "platform/audio/AudioFIFO.h" | |
34 #include "platform/audio/AudioSourceProvider.h" | |
35 #include "wtf/Allocator.h" | |
36 | |
37 namespace blink { | |
38 | |
39 // A FIFO (First In First Out) buffer to handle mismatches in buffer sizes | |
40 // between a provider and receiver. The receiver will "pull" data from this | |
41 // FIFO. If data is already available in the FIFO, it is provided to the | |
42 // receiver. If insufficient data is available to satisfy the request, the FIFO | |
43 // will ask the provider for more data when necessary to fulfill a request. | |
44 // Contrast this with a "push" FIFO, where the sender pushes data to the FIFO | |
45 // which will itself push the data to the receiver when the FIFO is full. | |
46 class PLATFORM_EXPORT AudioPullFIFO { | |
47 USING_FAST_MALLOC(AudioPullFIFO); | |
48 WTF_MAKE_NONCOPYABLE(AudioPullFIFO); | |
49 | |
50 public: | |
51 // Create a FIFO that gets data from |provider|. The FIFO will be large | |
52 // enough to hold |fifoLength| frames of data of |numberOfChannels| channels. | |
53 // The AudioSourceProvider will be asked to produce |providerSize| frames | |
54 // when the FIFO needs more data. | |
55 AudioPullFIFO(AudioSourceProvider& audioProvider, | |
56 unsigned numberOfChannels, | |
57 size_t fifoLength, | |
58 size_t providerSize); | |
59 | |
60 // Read |framesToConsume| frames from the FIFO into the destination. If the | |
61 // FIFO does not have enough data, we ask the |provider| to get more data to | |
62 // fulfill the request. | |
63 void consume(AudioBus* destination, size_t framesToConsume); | |
64 | |
65 private: | |
66 // Fill the FIFO buffer with at least |numberOfFrames| more data. | |
67 void fillBuffer(size_t numberOfFrames); | |
68 | |
69 // The provider of the data in our FIFO. | |
70 AudioSourceProvider& m_provider; | |
71 | |
72 // The actual FIFO | |
73 AudioFIFO m_fifo; | |
74 | |
75 // Number of frames of data that the provider will produce per call. | |
76 unsigned m_providerSize; | |
77 | |
78 // Temporary workspace to hold the data from the provider. | |
79 RefPtr<AudioBus> m_tempBus; | |
80 }; | |
81 | |
82 } // namespace blink | |
83 | |
84 #endif // AudioPullFIFO.h | |
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