Home | History | Annotate | Download | only in webaudio 
      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 AudioScheduledSourceNode_h
     30 #define AudioScheduledSourceNode_h
     31 
     32 #include "modules/webaudio/AudioSourceNode.h"
     33 
     34 namespace blink {
     35 
     36 class AudioBus;
     37 
     38 class AudioScheduledSourceNode : public AudioSourceNode {
     39 public:
     40     // These are the possible states an AudioScheduledSourceNode can be in:
     41     //
     42     // UNSCHEDULED_STATE - Initial playback state. Created, but not yet scheduled.
     43     // SCHEDULED_STATE - Scheduled to play (via start()), but not yet playing.
     44     // PLAYING_STATE - Generating sound.
     45     // FINISHED_STATE - Finished generating sound.
     46     //
     47     // The state can only transition to the next state, except for the FINISHED_STATE which can
     48     // never be changed.
     49     enum PlaybackState {
     50         // These must be defined with the same names and values as in the .idl file.
     51         UNSCHEDULED_STATE = 0,
     52         SCHEDULED_STATE = 1,
     53         PLAYING_STATE = 2,
     54         FINISHED_STATE = 3
     55     };
     56 
     57     AudioScheduledSourceNode(AudioContext*, float sampleRate);
     58 
     59     // Scheduling.
     60     void start(ExceptionState& exceptionState) { start(0.0, exceptionState); }
     61     void start(double when, ExceptionState&);
     62     void stop(ExceptionState& exceptionState) { stop(0.0, exceptionState); }
     63     void stop(double when, ExceptionState&);
     64 
     65     unsigned short playbackState() const { return static_cast<unsigned short>(m_playbackState); }
     66     bool isPlayingOrScheduled() const { return m_playbackState == PLAYING_STATE || m_playbackState == SCHEDULED_STATE; }
     67     bool hasFinished() const { return m_playbackState == FINISHED_STATE; }
     68 
     69     EventListener* onended() { return getAttributeEventListener(EventTypeNames::ended); }
     70     void setOnended(PassRefPtr<EventListener>);
     71 
     72 protected:
     73     // Get frame information for the current time quantum.
     74     // We handle the transition into PLAYING_STATE and FINISHED_STATE here,
     75     // zeroing out portions of the outputBus which are outside the range of startFrame and endFrame.
     76     //
     77     // Each frame time is relative to the context's currentSampleFrame().
     78     // quantumFrameOffset    : Offset frame in this time quantum to start rendering.
     79     // nonSilentFramesToProcess : Number of frames rendering non-silence (will be <= quantumFrameSize).
     80     void updateSchedulingInfo(size_t quantumFrameSize,
     81                               AudioBus* outputBus,
     82                               size_t& quantumFrameOffset,
     83                               size_t& nonSilentFramesToProcess);
     84 
     85     // Called when we have no more sound to play or the noteOff() time has been reached.
     86     virtual void finish();
     87 
     88     void notifyEnded();
     89 
     90     PlaybackState m_playbackState;
     91 
     92     // m_startTime is the time to start playing based on the context's timeline (0 or a time less than the context's current time means "now").
     93     double m_startTime; // in seconds
     94 
     95     // m_endTime is the time to stop playing based on the context's timeline (0 or a time less than the context's current time means "now").
     96     // If it hasn't been set explicitly, then the sound will not stop playing (if looping) or will stop when the end of the AudioBuffer
     97     // has been reached.
     98     double m_endTime; // in seconds
     99 
    100     bool m_hasEndedListener;
    101 
    102     static const double UnknownTime;
    103 };
    104 
    105 } // namespace blink
    106 
    107 #endif // AudioScheduledSourceNode_h
    108