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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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