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 * 1. Redistributions of source code must retain the above copyright 8 * notice, this list of conditions and the following disclaimer. 9 * 2. Redistributions in binary form must reproduce the above copyright 10 * notice, this list of conditions and the following disclaimer in the 11 * documentation and/or other materials provided with the distribution. 12 * 13 * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS'' AND ANY 14 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED 15 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE 16 * DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS BE LIABLE FOR ANY 17 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES 18 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 19 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON 20 * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 21 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS 22 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 23 */ 24 25 #ifndef ScriptProcessorNode_h 26 #define ScriptProcessorNode_h 27 28 #include "platform/audio/AudioBus.h" 29 #include "modules/webaudio/AudioNode.h" 30 #include "wtf/Forward.h" 31 #include "wtf/PassRefPtr.h" 32 #include "wtf/RefPtr.h" 33 #include "wtf/Vector.h" 34 35 namespace blink { 36 37 class AudioBuffer; 38 class AudioContext; 39 class AudioProcessingEvent; 40 41 // ScriptProcessorNode is an AudioNode which allows for arbitrary synthesis or processing directly using JavaScript. 42 // The API allows for a variable number of inputs and outputs, although it must have at least one input or output. 43 // This basic implementation supports no more than one input and output. 44 // The "onaudioprocess" attribute is an event listener which will get called periodically with an AudioProcessingEvent which has 45 // AudioBuffers for each input and output. 46 47 class ScriptProcessorNode FINAL : public AudioNode { 48 DEFINE_WRAPPERTYPEINFO(); 49 public: 50 // bufferSize must be one of the following values: 256, 512, 1024, 2048, 4096, 8192, 16384. 51 // This value controls how frequently the onaudioprocess event handler is called and how many sample-frames need to be processed each call. 52 // Lower numbers for bufferSize will result in a lower (better) latency. Higher numbers will be necessary to avoid audio breakup and glitches. 53 // The value chosen must carefully balance between latency and audio quality. 54 static ScriptProcessorNode* create(AudioContext*, float sampleRate, size_t bufferSize, unsigned numberOfInputChannels, unsigned numberOfOutputChannels); 55 56 virtual ~ScriptProcessorNode(); 57 58 // AudioNode 59 virtual void dispose() OVERRIDE; 60 virtual void process(size_t framesToProcess) OVERRIDE; 61 virtual void initialize() OVERRIDE; 62 virtual void uninitialize() OVERRIDE; 63 64 size_t bufferSize() const { return m_bufferSize; } 65 66 DEFINE_ATTRIBUTE_EVENT_LISTENER(audioprocess); 67 68 void trace(Visitor*); 69 70 private: 71 virtual double tailTime() const OVERRIDE; 72 virtual double latencyTime() const OVERRIDE; 73 74 ScriptProcessorNode(AudioContext*, float sampleRate, size_t bufferSize, unsigned numberOfInputChannels, unsigned numberOfOutputChannels); 75 76 void fireProcessEvent(); 77 78 // Double buffering 79 unsigned doubleBufferIndex() const { return m_doubleBufferIndex; } 80 void swapBuffers() { m_doubleBufferIndex = 1 - m_doubleBufferIndex; } 81 unsigned m_doubleBufferIndex; 82 unsigned m_doubleBufferIndexForEvent; 83 HeapVector<Member<AudioBuffer> > m_inputBuffers; 84 HeapVector<Member<AudioBuffer> > m_outputBuffers; 85 86 size_t m_bufferSize; 87 unsigned m_bufferReadWriteIndex; 88 89 unsigned m_numberOfInputChannels; 90 unsigned m_numberOfOutputChannels; 91 92 RefPtr<AudioBus> m_internalInputBus; 93 // Synchronize process() with fireProcessEvent(). 94 mutable Mutex m_processEventLock; 95 }; 96 97 } // namespace blink 98 99 #endif // ScriptProcessorNode_h 100