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