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      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 AudioBufferSourceNode_h
     26 #define AudioBufferSourceNode_h
     27 
     28 #include "platform/audio/AudioBus.h"
     29 #include "modules/webaudio/AudioBuffer.h"
     30 #include "modules/webaudio/AudioParam.h"
     31 #include "modules/webaudio/AudioScheduledSourceNode.h"
     32 #include "modules/webaudio/PannerNode.h"
     33 #include "wtf/OwnPtr.h"
     34 #include "wtf/PassRefPtr.h"
     35 #include "wtf/RefPtr.h"
     36 #include "wtf/Threading.h"
     37 
     38 namespace WebCore {
     39 
     40 class AudioContext;
     41 
     42 // AudioBufferSourceNode is an AudioNode representing an audio source from an in-memory audio asset represented by an AudioBuffer.
     43 // It generally will be used for short sounds which require a high degree of scheduling flexibility (can playback in rhythmically perfect ways).
     44 
     45 class AudioBufferSourceNode : public AudioScheduledSourceNode {
     46 public:
     47     static PassRefPtr<AudioBufferSourceNode> create(AudioContext*, float sampleRate);
     48 
     49     virtual ~AudioBufferSourceNode();
     50 
     51     // AudioNode
     52     virtual void process(size_t framesToProcess);
     53     virtual void reset();
     54 
     55     // setBuffer() is called on the main thread. This is the buffer we use for playback.
     56     void setBuffer(AudioBuffer*, ExceptionState&);
     57     AudioBuffer* buffer() { return m_buffer.get(); }
     58 
     59     // numberOfChannels() returns the number of output channels.  This value equals the number of channels from the buffer.
     60     // If a new buffer is set with a different number of channels, then this value will dynamically change.
     61     unsigned numberOfChannels();
     62 
     63     // Play-state
     64     void start(ExceptionState&);
     65     void start(double when, ExceptionState&);
     66     void start(double when, double grainOffset, ExceptionState&);
     67     void start(double when, double grainOffset, double grainDuration, ExceptionState&);
     68 
     69     void noteGrainOn(double when, double grainOffset, double grainDuration, ExceptionState&);
     70 
     71     // Note: the attribute was originally exposed as .looping, but to be more consistent in naming with <audio>
     72     // and with how it's described in the specification, the proper attribute name is .loop
     73     // The old attribute is kept for backwards compatibility.
     74     bool loop() const { return m_isLooping; }
     75     void setLoop(bool looping) { m_isLooping = looping; }
     76 
     77     // Loop times in seconds.
     78     double loopStart() const { return m_loopStart; }
     79     double loopEnd() const { return m_loopEnd; }
     80     void setLoopStart(double loopStart) { m_loopStart = loopStart; }
     81     void setLoopEnd(double loopEnd) { m_loopEnd = loopEnd; }
     82 
     83     AudioParam* gain() { return m_gain.get(); }
     84     AudioParam* playbackRate() { return m_playbackRate.get(); }
     85 
     86     // If a panner node is set, then we can incorporate doppler shift into the playback pitch rate.
     87     void setPannerNode(PannerNode*);
     88     void clearPannerNode();
     89 
     90     // If we are no longer playing, propogate silence ahead to downstream nodes.
     91     virtual bool propagatesSilence() const;
     92 
     93     // AudioScheduledSourceNode
     94     virtual void finish() OVERRIDE;
     95 
     96 private:
     97     AudioBufferSourceNode(AudioContext*, float sampleRate);
     98 
     99     void startPlaying(bool isGrain, double when, double grainOffset, double grainDuration, ExceptionState&);
    100 
    101     // Returns true on success.
    102     bool renderFromBuffer(AudioBus*, unsigned destinationFrameOffset, size_t numberOfFrames);
    103 
    104     // Render silence starting from "index" frame in AudioBus.
    105     inline bool renderSilenceAndFinishIfNotLooping(AudioBus*, unsigned index, size_t framesToProcess);
    106 
    107     // m_buffer holds the sample data which this node outputs.
    108     RefPtr<AudioBuffer> m_buffer;
    109 
    110     // Pointers for the buffer and destination.
    111     OwnPtr<const float*[]> m_sourceChannels;
    112     OwnPtr<float*[]> m_destinationChannels;
    113 
    114     // Used for the "gain" and "playbackRate" attributes.
    115     RefPtr<AudioParam> m_gain;
    116     RefPtr<AudioParam> m_playbackRate;
    117 
    118     // If m_isLooping is false, then this node will be done playing and become inactive after it reaches the end of the sample data in the buffer.
    119     // If true, it will wrap around to the start of the buffer each time it reaches the end.
    120     bool m_isLooping;
    121 
    122     double m_loopStart;
    123     double m_loopEnd;
    124 
    125     // m_virtualReadIndex is a sample-frame index into our buffer representing the current playback position.
    126     // Since it's floating-point, it has sub-sample accuracy.
    127     double m_virtualReadIndex;
    128 
    129     // Granular playback
    130     bool m_isGrain;
    131     double m_grainOffset; // in seconds
    132     double m_grainDuration; // in seconds
    133 
    134     // totalPitchRate() returns the instantaneous pitch rate (non-time preserving).
    135     // It incorporates the base pitch rate, any sample-rate conversion factor from the buffer, and any doppler shift from an associated panner node.
    136     double totalPitchRate();
    137 
    138     // m_lastGain provides continuity when we dynamically adjust the gain.
    139     float m_lastGain;
    140 
    141     // We optionally keep track of a panner node which has a doppler shift that is incorporated into
    142     // the pitch rate. We manually manage ref-counting because we want to use RefTypeConnection.
    143     PannerNode* m_pannerNode;
    144 
    145     // This synchronizes process() with setBuffer() which can cause dynamic channel count changes.
    146     mutable Mutex m_processLock;
    147 };
    148 
    149 } // namespace WebCore
    150 
    151 #endif // AudioBufferSourceNode_h
    152