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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  * 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 #include "config.h"
     26 
     27 #if ENABLE(WEB_AUDIO)
     28 
     29 #include "modules/webaudio/AudioScheduledSourceNode.h"
     30 
     31 #include "core/dom/Event.h"
     32 #include "core/platform/audio/AudioUtilities.h"
     33 #include "modules/webaudio/AudioContext.h"
     34 #include <algorithm>
     35 #include "wtf/MathExtras.h"
     36 
     37 using namespace std;
     38 
     39 namespace WebCore {
     40 
     41 const double AudioScheduledSourceNode::UnknownTime = -1;
     42 
     43 AudioScheduledSourceNode::AudioScheduledSourceNode(AudioContext* context, float sampleRate)
     44     : AudioSourceNode(context, sampleRate)
     45     , m_playbackState(UNSCHEDULED_STATE)
     46     , m_startTime(0)
     47     , m_endTime(UnknownTime)
     48     , m_hasEndedListener(false)
     49 {
     50 }
     51 
     52 void AudioScheduledSourceNode::updateSchedulingInfo(size_t quantumFrameSize,
     53                                                     AudioBus* outputBus,
     54                                                     size_t& quantumFrameOffset,
     55                                                     size_t& nonSilentFramesToProcess)
     56 {
     57     ASSERT(outputBus);
     58     if (!outputBus)
     59         return;
     60 
     61     ASSERT(quantumFrameSize == AudioNode::ProcessingSizeInFrames);
     62     if (quantumFrameSize != AudioNode::ProcessingSizeInFrames)
     63         return;
     64 
     65     double sampleRate = this->sampleRate();
     66 
     67     // quantumStartFrame     : Start frame of the current time quantum.
     68     // quantumEndFrame       : End frame of the current time quantum.
     69     // startFrame            : Start frame for this source.
     70     // endFrame              : End frame for this source.
     71     size_t quantumStartFrame = context()->currentSampleFrame();
     72     size_t quantumEndFrame = quantumStartFrame + quantumFrameSize;
     73     size_t startFrame = AudioUtilities::timeToSampleFrame(m_startTime, sampleRate);
     74     size_t endFrame = m_endTime == UnknownTime ? 0 : AudioUtilities::timeToSampleFrame(m_endTime, sampleRate);
     75 
     76     // If we know the end time and it's already passed, then don't bother doing any more rendering this cycle.
     77     if (m_endTime != UnknownTime && endFrame <= quantumStartFrame)
     78         finish();
     79 
     80     if (m_playbackState == UNSCHEDULED_STATE || m_playbackState == FINISHED_STATE || startFrame >= quantumEndFrame) {
     81         // Output silence.
     82         outputBus->zero();
     83         nonSilentFramesToProcess = 0;
     84         return;
     85     }
     86 
     87     // Check if it's time to start playing.
     88     if (m_playbackState == SCHEDULED_STATE) {
     89         // Increment the active source count only if we're transitioning from SCHEDULED_STATE to PLAYING_STATE.
     90         m_playbackState = PLAYING_STATE;
     91         context()->incrementActiveSourceCount();
     92     }
     93 
     94     quantumFrameOffset = startFrame > quantumStartFrame ? startFrame - quantumStartFrame : 0;
     95     quantumFrameOffset = min(quantumFrameOffset, quantumFrameSize); // clamp to valid range
     96     nonSilentFramesToProcess = quantumFrameSize - quantumFrameOffset;
     97 
     98     if (!nonSilentFramesToProcess) {
     99         // Output silence.
    100         outputBus->zero();
    101         return;
    102     }
    103 
    104     // Handle silence before we start playing.
    105     // Zero any initial frames representing silence leading up to a rendering start time in the middle of the quantum.
    106     if (quantumFrameOffset) {
    107         for (unsigned i = 0; i < outputBus->numberOfChannels(); ++i)
    108             memset(outputBus->channel(i)->mutableData(), 0, sizeof(float) * quantumFrameOffset);
    109     }
    110 
    111     // Handle silence after we're done playing.
    112     // If the end time is somewhere in the middle of this time quantum, then zero out the
    113     // frames from the end time to the very end of the quantum.
    114     if (m_endTime != UnknownTime && endFrame >= quantumStartFrame && endFrame < quantumEndFrame) {
    115         size_t zeroStartFrame = endFrame - quantumStartFrame;
    116         size_t framesToZero = quantumFrameSize - zeroStartFrame;
    117 
    118         bool isSafe = zeroStartFrame < quantumFrameSize && framesToZero <= quantumFrameSize && zeroStartFrame + framesToZero <= quantumFrameSize;
    119         ASSERT(isSafe);
    120 
    121         if (isSafe) {
    122             if (framesToZero > nonSilentFramesToProcess)
    123                 nonSilentFramesToProcess = 0;
    124             else
    125                 nonSilentFramesToProcess -= framesToZero;
    126 
    127             for (unsigned i = 0; i < outputBus->numberOfChannels(); ++i)
    128                 memset(outputBus->channel(i)->mutableData() + zeroStartFrame, 0, sizeof(float) * framesToZero);
    129         }
    130 
    131         finish();
    132     }
    133 
    134     return;
    135 }
    136 
    137 void AudioScheduledSourceNode::start(double when)
    138 {
    139     ASSERT(isMainThread());
    140     if (m_playbackState != UNSCHEDULED_STATE)
    141         return;
    142 
    143     m_startTime = when;
    144     m_playbackState = SCHEDULED_STATE;
    145 }
    146 
    147 void AudioScheduledSourceNode::stop(double when)
    148 {
    149     ASSERT(isMainThread());
    150     if (!(m_playbackState == SCHEDULED_STATE || m_playbackState == PLAYING_STATE))
    151         return;
    152 
    153     when = max(0.0, when);
    154     m_endTime = when;
    155 }
    156 
    157 void AudioScheduledSourceNode::noteOn(double when)
    158 {
    159     start(when);
    160 }
    161 
    162 void AudioScheduledSourceNode::noteOff(double when)
    163 {
    164     stop(when);
    165 }
    166 
    167 void AudioScheduledSourceNode::setOnended(PassRefPtr<EventListener> listener, DOMWrapperWorld* isolatedWorld)
    168 {
    169     m_hasEndedListener = listener;
    170     setAttributeEventListener(eventNames().endedEvent, listener, isolatedWorld);
    171 }
    172 
    173 void AudioScheduledSourceNode::finish()
    174 {
    175     if (m_playbackState != FINISHED_STATE) {
    176         // Let the context dereference this AudioNode.
    177         context()->notifyNodeFinishedProcessing(this);
    178         m_playbackState = FINISHED_STATE;
    179         context()->decrementActiveSourceCount();
    180     }
    181 
    182     if (m_hasEndedListener) {
    183         // |task| will keep the AudioScheduledSourceNode alive until the listener has been handled.
    184         OwnPtr<NotifyEndedTask> task = adoptPtr(new NotifyEndedTask(this));
    185         callOnMainThread(&AudioScheduledSourceNode::notifyEndedDispatch, task.leakPtr());
    186     }
    187 }
    188 
    189 void AudioScheduledSourceNode::notifyEndedDispatch(void* userData)
    190 {
    191     OwnPtr<NotifyEndedTask> task = adoptPtr(static_cast<NotifyEndedTask*>(userData));
    192 
    193     task->notifyEnded();
    194 }
    195 
    196 AudioScheduledSourceNode::NotifyEndedTask::NotifyEndedTask(PassRefPtr<AudioScheduledSourceNode> sourceNode)
    197     : m_scheduledNode(sourceNode)
    198 {
    199 }
    200 
    201 void AudioScheduledSourceNode::NotifyEndedTask::notifyEnded()
    202 {
    203     RefPtr<Event> event = Event::create(eventNames().endedEvent, FALSE, FALSE);
    204     event->setTarget(m_scheduledNode);
    205     m_scheduledNode->dispatchEvent(event.get());
    206 }
    207 
    208 } // namespace WebCore
    209 
    210 #endif // ENABLE(WEB_AUDIO)
    211