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1 /* | 1 /* |
2 * Copyright (C) 2012 Google Inc. All rights reserved. | 2 * Copyright (C) 2012 Google Inc. All rights reserved. |
3 * | 3 * |
4 * Redistribution and use in source and binary forms, with or without | 4 * Redistribution and use in source and binary forms, with or without |
5 * modification, are permitted provided that the following conditions | 5 * modification, are permitted provided that the following conditions |
6 * are met: | 6 * are met: |
7 * | 7 * |
8 * 1. Redistributions of source code must retain the above copyright | 8 * 1. Redistributions of source code must retain the above copyright |
9 * notice, this list of conditions and the following disclaimer. | 9 * notice, this list of conditions and the following disclaimer. |
10 * 2. Redistributions in binary form must reproduce the above copyright | 10 * 2. Redistributions in binary form must reproduce the above copyright |
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29 #ifndef AudioPullFIFO_h | 29 #ifndef AudioPullFIFO_h |
30 #define AudioPullFIFO_h | 30 #define AudioPullFIFO_h |
31 | 31 |
32 #include "platform/audio/AudioBus.h" | 32 #include "platform/audio/AudioBus.h" |
33 #include "platform/audio/AudioFIFO.h" | 33 #include "platform/audio/AudioFIFO.h" |
34 #include "platform/audio/AudioSourceProvider.h" | 34 #include "platform/audio/AudioSourceProvider.h" |
35 #include "wtf/Allocator.h" | 35 #include "wtf/Allocator.h" |
36 | 36 |
37 namespace blink { | 37 namespace blink { |
38 | 38 |
39 // A FIFO (First In First Out) buffer to handle mismatches in buffer sizes betwe
en a provider and | 39 // A FIFO (First In First Out) buffer to handle mismatches in buffer sizes |
40 // receiver. The receiver will "pull" data from this FIFO. If data is already av
ailable in the | 40 // between a provider and receiver. The receiver will "pull" data from this |
41 // FIFO, it is provided to the receiver. If insufficient data is available to sa
tisfy the request, | 41 // FIFO. If data is already available in the FIFO, it is provided to the |
42 // the FIFO will ask the provider for more data when necessary to fulfill a requ
est. Contrast this | 42 // receiver. If insufficient data is available to satisfy the request, the FIFO |
43 // with a "push" FIFO, where the sender pushes data to the FIFO which will itsel
f push the data to | 43 // will ask the provider for more data when necessary to fulfill a request. |
44 // the receiver when the FIFO is full. | 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. |
45 class PLATFORM_EXPORT AudioPullFIFO { | 46 class PLATFORM_EXPORT AudioPullFIFO { |
46 USING_FAST_MALLOC(AudioPullFIFO); | 47 USING_FAST_MALLOC(AudioPullFIFO); |
47 WTF_MAKE_NONCOPYABLE(AudioPullFIFO); | 48 WTF_MAKE_NONCOPYABLE(AudioPullFIFO); |
48 | 49 |
49 public: | 50 public: |
50 // Create a FIFO that gets data from |provider|. The FIFO will be large enough
to hold | 51 // Create a FIFO that gets data from |provider|. The FIFO will be large |
51 // |fifoLength| frames of data of |numberOfChannels| channels. The AudioSource
Provider will be | 52 // enough to hold |fifoLength| frames of data of |numberOfChannels| channels. |
52 // asked to produce |providerSize| frames when the FIFO needs more data. | 53 // The AudioSourceProvider will be asked to produce |providerSize| frames |
| 54 // when the FIFO needs more data. |
53 AudioPullFIFO(AudioSourceProvider& audioProvider, | 55 AudioPullFIFO(AudioSourceProvider& audioProvider, |
54 unsigned numberOfChannels, | 56 unsigned numberOfChannels, |
55 size_t fifoLength, | 57 size_t fifoLength, |
56 size_t providerSize); | 58 size_t providerSize); |
57 | 59 |
58 // Read |framesToConsume| frames from the FIFO into the destination. If the FI
FO does not have | 60 // Read |framesToConsume| frames from the FIFO into the destination. If the |
59 // enough data, we ask the |provider| to get more data to fulfill the request. | 61 // FIFO does not have enough data, we ask the |provider| to get more data to |
| 62 // fulfill the request. |
60 void consume(AudioBus* destination, size_t framesToConsume); | 63 void consume(AudioBus* destination, size_t framesToConsume); |
61 | 64 |
62 private: | 65 private: |
63 // Fill the FIFO buffer with at least |numberOfFrames| more data. | 66 // Fill the FIFO buffer with at least |numberOfFrames| more data. |
64 void fillBuffer(size_t numberOfFrames); | 67 void fillBuffer(size_t numberOfFrames); |
65 | 68 |
66 // The provider of the data in our FIFO. | 69 // The provider of the data in our FIFO. |
67 AudioSourceProvider& m_provider; | 70 AudioSourceProvider& m_provider; |
68 | 71 |
69 // The actual FIFO | 72 // The actual FIFO |
70 AudioFIFO m_fifo; | 73 AudioFIFO m_fifo; |
71 | 74 |
72 // Number of frames of data that the provider will produce per call. | 75 // Number of frames of data that the provider will produce per call. |
73 unsigned m_providerSize; | 76 unsigned m_providerSize; |
74 | 77 |
75 // Temporary workspace to hold the data from the provider. | 78 // Temporary workspace to hold the data from the provider. |
76 RefPtr<AudioBus> m_tempBus; | 79 RefPtr<AudioBus> m_tempBus; |
77 }; | 80 }; |
78 | 81 |
79 } // namespace blink | 82 } // namespace blink |
80 | 83 |
81 #endif // AudioPullFIFO.h | 84 #endif // AudioPullFIFO.h |
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