The Tor Browser: content/media/webaudio/OscillatorNode.cpp@97036ab72558 (annotated)

content/media/webaudio/OscillatorNode.cpp@97036ab72558 (annotated)

content/media/webaudio/OscillatorNode.cpp

Tue, 06 Jan 2015 21:39:09 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Tue, 06 Jan 2015 21:39:09 +0100
branch: TOR_BUG_9701
changeset 8: 97036ab72558
permissions: -rw-r--r--

Conditionally force memory storage according to privacy.thirdparty.isolate;
This solves Tor bug #9701, complying with disk avoidance documented in
https://www.torproject.org/projects/torbrowser/design/#disk-avoidance.

 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
 /* vim:set ts=2 sw=2 sts=2 et cindent: */
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 #include "OscillatorNode.h"
 #include "AudioNodeEngine.h"
 #include "AudioNodeStream.h"
 #include "AudioDestinationNode.h"
 #include "WebAudioUtils.h"
 #include "blink/PeriodicWave.h"
 namespace mozilla {
 namespace dom {
 NS_IMPL_CYCLE_COLLECTION_INHERITED(OscillatorNode, AudioNode,
                                    mPeriodicWave, mFrequency, mDetune)
 NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION_INHERITED(OscillatorNode)
 NS_INTERFACE_MAP_END_INHERITING(AudioNode)
 NS_IMPL_ADDREF_INHERITED(OscillatorNode, AudioNode)
 NS_IMPL_RELEASE_INHERITED(OscillatorNode, AudioNode)
 static const float sLeakTriangle = 0.995f;
 static const float sLeak = 0.999f;
 class DCBlocker
 {
 public:
   // These are sane defauts when the initial mPhase is zero
   DCBlocker(float aLastInput = 0.0f,
             float aLastOutput = 0.0f,
             float aPole = 0.995)
     :mLastInput(aLastInput),
      mLastOutput(aLastOutput),
      mPole(aPole)
   {
     MOZ_ASSERT(aPole > 0);
   }
   inline float Process(float aInput)
   {
     float out;
     out = mLastOutput * mPole + aInput - mLastInput;
     mLastOutput = out;
     mLastInput = aInput;
     return out;
   }
 private:
   float mLastInput;
   float mLastOutput;
   float mPole;
 };
 class OscillatorNodeEngine : public AudioNodeEngine
 {
 public:
   OscillatorNodeEngine(AudioNode* aNode, AudioDestinationNode* aDestination)
     : AudioNodeEngine(aNode)
     , mSource(nullptr)
     , mDestination(static_cast<AudioNodeStream*> (aDestination->Stream()))
     , mStart(-1)
     , mStop(TRACK_TICKS_MAX)
     // Keep the default values in sync with OscillatorNode::OscillatorNode.
     , mFrequency(440.f)
     , mDetune(0.f)
     , mType(OscillatorType::Sine)
     , mPhase(0.)
     // mSquare, mTriangle, and mSaw are not used for default type "sine".
     // They are initialized if and when switching to the OscillatorTypes that
     // use them.
     // mFinalFrequency, mNumberOfHarmonics, mSignalPeriod, mAmplitudeAtZero,
     // mPhaseIncrement, and mPhaseWrap are initialized in
     // UpdateParametersIfNeeded() when mRecomputeParameters is set.
     , mRecomputeParameters(true)
     , mCustomLength(0)
   {
   }
   void SetSourceStream(AudioNodeStream* aSource)
   {
     mSource = aSource;
   }
   enum Parameters {
     FREQUENCY,
     DETUNE,
     TYPE,
     PERIODICWAVE,
     START,
     STOP,
   };
   void SetTimelineParameter(uint32_t aIndex,
                             const AudioParamTimeline& aValue,
                             TrackRate aSampleRate) MOZ_OVERRIDE
   {
     mRecomputeParameters = true;
     switch (aIndex) {
     case FREQUENCY:
       MOZ_ASSERT(mSource && mDestination);
       mFrequency = aValue;
       WebAudioUtils::ConvertAudioParamToTicks(mFrequency, mSource, mDestination);
       break;
     case DETUNE:
       MOZ_ASSERT(mSource && mDestination);
       mDetune = aValue;
       WebAudioUtils::ConvertAudioParamToTicks(mDetune, mSource, mDestination);
       break;
     default:
       NS_ERROR("Bad OscillatorNodeEngine TimelineParameter");
     }
   }
   virtual void SetStreamTimeParameter(uint32_t aIndex, TrackTicks aParam)
   {
     switch (aIndex) {
     case START: mStart = aParam; break;
     case STOP: mStop = aParam; break;
     default:
       NS_ERROR("Bad OscillatorNodeEngine StreamTimeParameter");
     }
   }
   virtual void SetInt32Parameter(uint32_t aIndex, int32_t aParam)
   {
     switch (aIndex) {
       case TYPE:
         // Set the new type.
         mType = static_cast<OscillatorType>(aParam);
         if (mType != OscillatorType::Custom) {
           // Forget any previous custom data.
           mCustomLength = 0;
           mCustom = nullptr;
           mPeriodicWave = nullptr;
           mRecomputeParameters = true;
         }
         // Update BLIT integrators with the new initial conditions.
         switch (mType) {
           case OscillatorType::Sine:
             mPhase = 0.0;
             break;
           case OscillatorType::Square:
             mPhase = 0.0;
             // Initial integration condition is -0.5, because our
             // square has 50% duty cycle.
             mSquare = -0.5;
             break;
           case OscillatorType::Triangle:
             // Initial mPhase and related integration condition so the
             // triangle is in the middle of the first upward slope.
             // XXX actually do the maths and put the right number here.
             mPhase = (float)(M_PI / 2);
             mSquare = 0.5;
             mTriangle = 0.0;
             break;
           case OscillatorType::Sawtooth:
             // Initial mPhase so the oscillator starts at the
             // middle of the ramp, per spec.
             mPhase = (float)(M_PI / 2);
             // mSaw = 0 when mPhase = pi/2.
             mSaw = 0.0;
             break;
           case OscillatorType::Custom:
             // Custom waveforms don't use BLIT.
             break;
           default:
             NS_ERROR("Bad OscillatorNodeEngine type parameter.");
         }
         // End type switch.
         break;
       case PERIODICWAVE:
         MOZ_ASSERT(aParam >= 0, "negative custom array length");
         mCustomLength = static_cast<uint32_t>(aParam);
         break;
       default:
         NS_ERROR("Bad OscillatorNodeEngine Int32Parameter.");
     }
     // End index switch.
   }
   virtual void SetBuffer(already_AddRefed<ThreadSharedFloatArrayBufferList> aBuffer)
   {
     MOZ_ASSERT(mCustomLength, "Custom buffer sent before length");
     mCustom = aBuffer;
     MOZ_ASSERT(mCustom->GetChannels() == 2,
                "PeriodicWave should have sent two channels");
     mPeriodicWave = WebCore::PeriodicWave::create(mSource->SampleRate(),
     mCustom->GetData(0), mCustom->GetData(1), mCustomLength);
   }
   void IncrementPhase()
   {
     mPhase += mPhaseIncrement;
     if (mPhase > mPhaseWrap) {
       mPhase -= mPhaseWrap;
     }
   }
   // Square and triangle are using a bipolar band-limited impulse train, saw is
   // using a normal band-limited impulse train.
   bool UsesBipolarBLIT() {
     return mType == OscillatorType::Square || mType == OscillatorType::Triangle;
   }
   void UpdateParametersIfNeeded(TrackTicks ticks, size_t count)
   {
     double frequency, detune;
     bool simpleFrequency = mFrequency.HasSimpleValue();
     bool simpleDetune = mDetune.HasSimpleValue();
     // Shortcut if frequency-related AudioParam are not automated, and we
     // already have computed the frequency information and related parameters.
     if (simpleFrequency && simpleDetune && !mRecomputeParameters) {
       return;
     }
     if (simpleFrequency) {
       frequency = mFrequency.GetValue();
     } else {
       frequency = mFrequency.GetValueAtTime(ticks, count);
     }
     if (simpleDetune) {
       detune = mDetune.GetValue();
     } else {
       detune = mDetune.GetValueAtTime(ticks, count);
     }
     mFinalFrequency = frequency * pow(2., detune / 1200.);
     mRecomputeParameters = false;
     // When using bipolar BLIT, we divide the signal period by two, because we
     // are using two BLIT out of phase.
     mSignalPeriod = UsesBipolarBLIT() ? 0.5 * mSource->SampleRate() / mFinalFrequency
                                       : mSource->SampleRate() / mFinalFrequency;
     // Wrap the phase accordingly:
     mPhaseWrap = UsesBipolarBLIT() || mType == OscillatorType::Sine ? 2 * M_PI
                                    : M_PI;
     // Even number of harmonics for bipolar blit, odd otherwise.
     mNumberOfHarmonics = UsesBipolarBLIT() ? 2 * floor(0.5 * mSignalPeriod)
                                            : 2 * floor(0.5 * mSignalPeriod) + 1;
     mPhaseIncrement = mType == OscillatorType::Sine ? 2 * M_PI / mSignalPeriod
                                                     : M_PI / mSignalPeriod;
     mAmplitudeAtZero = mNumberOfHarmonics / mSignalPeriod;
   }
   void FillBounds(float* output, TrackTicks ticks,
                   uint32_t& start, uint32_t& end)
   {
     MOZ_ASSERT(output);
     static_assert(TrackTicks(WEBAUDIO_BLOCK_SIZE) < UINT_MAX,
         "WEBAUDIO_BLOCK_SIZE overflows interator bounds.");
     start = 0;
     if (ticks < mStart) {
       start = mStart - ticks;
       for (uint32_t i = 0; i < start; ++i) {
         output[i] = 0.0;
       }
     }
     end = WEBAUDIO_BLOCK_SIZE;
     if (ticks + end > mStop) {
       end = mStop - ticks;
       for (uint32_t i = end; i < WEBAUDIO_BLOCK_SIZE; ++i) {
         output[i] = 0.0;
       }
     }
   }
   float BipolarBLIT()
   {
     float blit;
     float denom = sin(mPhase);
     if (fabs(denom) < std::numeric_limits<float>::epsilon()) {
       if (mPhase < 0.1f || mPhase > 2 * M_PI - 0.1f) {
         blit = mAmplitudeAtZero;
       } else {
         blit = -mAmplitudeAtZero;
       }
     } else {
       blit = sin(mNumberOfHarmonics * mPhase);
       blit /= mSignalPeriod * denom;
     }
     return blit;
   }
   float UnipolarBLIT()
   {
     float blit;
     float denom = sin(mPhase);
     if (fabs(denom) <= std::numeric_limits<float>::epsilon()) {
       blit = mAmplitudeAtZero;
     } else {
       blit = sin(mNumberOfHarmonics * mPhase);
       blit /= mSignalPeriod * denom;
     }
     return blit;
   }
   void ComputeSine(float * aOutput, TrackTicks ticks, uint32_t aStart, uint32_t aEnd)
   {
     for (uint32_t i = aStart; i < aEnd; ++i) {
       UpdateParametersIfNeeded(ticks, i);
       aOutput[i] = sin(mPhase);
       IncrementPhase();
     }
   }
   void ComputeSquare(float * aOutput, TrackTicks ticks, uint32_t aStart, uint32_t aEnd)
   {
     for (uint32_t i = aStart; i < aEnd; ++i) {
       UpdateParametersIfNeeded(ticks, i);
       // Integration to get us a square. It turns out we can have a
       // pure integrator here.
       mSquare = mSquare * sLeak + BipolarBLIT();
       aOutput[i] = mSquare;
       // maybe we want to apply a gain, the wg has not decided yet
       aOutput[i] *= 1.5;
       IncrementPhase();
     }
   }
   void ComputeSawtooth(float * aOutput, TrackTicks ticks, uint32_t aStart, uint32_t aEnd)
   {
     float dcoffset;
     for (uint32_t i = aStart; i < aEnd; ++i) {
       UpdateParametersIfNeeded(ticks, i);
       // DC offset so the Saw does not ramp up to infinity when integrating.
       dcoffset = mFinalFrequency / mSource->SampleRate();
       // Integrate and offset so we get mAmplitudeAtZero sawtooth. We have a
       // very low frequency component somewhere here, but I'm not sure where.
       mSaw = mSaw * sLeak + (UnipolarBLIT() - dcoffset);
       // reverse the saw so we are spec compliant
       aOutput[i] = -mSaw * 1.5;
       IncrementPhase();
     }
   }
   void ComputeTriangle(float * aOutput, TrackTicks ticks, uint32_t aStart, uint32_t aEnd)
   {
     for (uint32_t i = aStart; i < aEnd; ++i) {
       UpdateParametersIfNeeded(ticks, i);
       // Integrate to get a square
       mSquare += BipolarBLIT();
       // Leaky integrate to get a triangle. We get too much dc offset if we don't
       // leaky integrate here.
       // C6 = k0 / period
       // (period is samplingrate / frequency, k0 = (PI/2)/(2*PI)) = 0.25
       float C6 = 0.25 / (mSource->SampleRate() / mFinalFrequency);
       mTriangle = mTriangle * sLeakTriangle + mSquare + C6;
       // DC Block, and scale back to [-1.0; 1.0]
       aOutput[i] = mDCBlocker.Process(mTriangle) / (mSignalPeriod/2) * 1.5;
       IncrementPhase();
     }
   }
   void ComputeCustom(float* aOutput,
                      TrackTicks ticks,
                      uint32_t aStart,
                      uint32_t aEnd)
   {
     MOZ_ASSERT(mPeriodicWave, "No custom waveform data");
     uint32_t periodicWaveSize = mPeriodicWave->periodicWaveSize();
     // Mask to wrap wave data indices into the range [0,periodicWaveSize).
     uint32_t indexMask = periodicWaveSize - 1;
     MOZ_ASSERT(periodicWaveSize && (periodicWaveSize & indexMask) == 0,
                "periodicWaveSize must be power of 2");
     float* higherWaveData = nullptr;
     float* lowerWaveData = nullptr;
     float tableInterpolationFactor;
     // Phase increment at frequency of 1 Hz.
     // mPhase runs [0,periodicWaveSize) here instead of [0,2*M_PI).
     float basePhaseIncrement =
       static_cast<float>(periodicWaveSize) / mSource->SampleRate();
     for (uint32_t i = aStart; i < aEnd; ++i) {
       UpdateParametersIfNeeded(ticks, i);
       mPeriodicWave->waveDataForFundamentalFrequency(mFinalFrequency,
                                                      lowerWaveData,
                                                      higherWaveData,
                                                      tableInterpolationFactor);
       // Bilinear interpolation between adjacent samples in each table.
       float floorPhase = floorf(mPhase);
       uint32_t j1 = floorPhase;
       j1 &= indexMask;
       uint32_t j2 = j1 + 1;
       j2 &= indexMask;
       float sampleInterpolationFactor = mPhase - floorPhase;
       float lower = (1.0f - sampleInterpolationFactor) * lowerWaveData[j1] +
                     sampleInterpolationFactor * lowerWaveData[j2];
       float higher = (1.0f - sampleInterpolationFactor) * higherWaveData[j1] +
                     sampleInterpolationFactor * higherWaveData[j2];
       aOutput[i] = (1.0f - tableInterpolationFactor) * lower +
                    tableInterpolationFactor * higher;
       // Calculate next phase position from wrapped value j1 to avoid loss of
       // precision at large values.
       mPhase =
         j1 + sampleInterpolationFactor + basePhaseIncrement * mFinalFrequency;
     }
   }
   void ComputeSilence(AudioChunk *aOutput)
   {
     aOutput->SetNull(WEBAUDIO_BLOCK_SIZE);
   }
   virtual void ProcessBlock(AudioNodeStream* aStream,
                             const AudioChunk& aInput,
                             AudioChunk* aOutput,
                             bool* aFinished) MOZ_OVERRIDE
   {
     MOZ_ASSERT(mSource == aStream, "Invalid source stream");
     TrackTicks ticks = aStream->GetCurrentPosition();
     if (mStart == -1) {
       ComputeSilence(aOutput);
       return;
     }
     if (ticks >= mStop) {
       // We've finished playing.
       ComputeSilence(aOutput);
       *aFinished = true;
       return;
     }
     if (ticks + WEBAUDIO_BLOCK_SIZE < mStart) {
       // We're not playing yet.
       ComputeSilence(aOutput);
       return;
     }
     AllocateAudioBlock(1, aOutput);
     float* output = static_cast<float*>(
         const_cast<void*>(aOutput->mChannelData[0]));
     uint32_t start, end;
     FillBounds(output, ticks, start, end);
     // Synthesize the correct waveform.
     switch(mType) {
       case OscillatorType::Sine:
         ComputeSine(output, ticks, start, end);
         break;
       case OscillatorType::Square:
         ComputeSquare(output, ticks, start, end);
         break;
       case OscillatorType::Triangle:
         ComputeTriangle(output, ticks, start, end);
         break;
       case OscillatorType::Sawtooth:
         ComputeSawtooth(output, ticks, start, end);
         break;
       case OscillatorType::Custom:
         ComputeCustom(output, ticks, start, end);
         break;
       default:
         ComputeSilence(aOutput);
     };
   }
   virtual size_t SizeOfExcludingThis(MallocSizeOf aMallocSizeOf) const MOZ_OVERRIDE
   {
     size_t amount = AudioNodeEngine::SizeOfExcludingThis(aMallocSizeOf);
     // Not owned:
     // - mSource
     // - mDestination
     // - mFrequency (internal ref owned by node)
     // - mDetune (internal ref owned by node)
     if (mCustom) {
       amount += mCustom->SizeOfIncludingThis(aMallocSizeOf);
     }
     if (mPeriodicWave) {
       amount += mPeriodicWave->sizeOfIncludingThis(aMallocSizeOf);
     }
     return amount;
   }
   virtual size_t SizeOfIncludingThis(MallocSizeOf aMallocSizeOf) const MOZ_OVERRIDE
   {
     return aMallocSizeOf(this) + SizeOfExcludingThis(aMallocSizeOf);
   }
   DCBlocker mDCBlocker;
   AudioNodeStream* mSource;
   AudioNodeStream* mDestination;
   TrackTicks mStart;
   TrackTicks mStop;
   AudioParamTimeline mFrequency;
   AudioParamTimeline mDetune;
   OscillatorType mType;
   float mPhase;
   float mFinalFrequency;
   uint32_t mNumberOfHarmonics;
   float mSignalPeriod;
   float mAmplitudeAtZero;
   float mPhaseIncrement;
   float mSquare;
   float mTriangle;
   float mSaw;
   float mPhaseWrap;
   bool mRecomputeParameters;
   nsRefPtr<ThreadSharedFloatArrayBufferList> mCustom;
   uint32_t mCustomLength;
   nsAutoPtr<WebCore::PeriodicWave> mPeriodicWave;
 };
 OscillatorNode::OscillatorNode(AudioContext* aContext)
   : AudioNode(aContext,
 ,
               ChannelCountMode::Max,
               ChannelInterpretation::Speakers)
   , mType(OscillatorType::Sine)
   , mFrequency(new AudioParam(MOZ_THIS_IN_INITIALIZER_LIST(),
                SendFrequencyToStream, 440.0f))
   , mDetune(new AudioParam(MOZ_THIS_IN_INITIALIZER_LIST(),
             SendDetuneToStream, 0.0f))
   , mStartCalled(false)
   , mStopped(false)
 {
   OscillatorNodeEngine* engine = new OscillatorNodeEngine(this, aContext->Destination());
   mStream = aContext->Graph()->CreateAudioNodeStream(engine, MediaStreamGraph::SOURCE_STREAM);
   engine->SetSourceStream(static_cast<AudioNodeStream*> (mStream.get()));
   mStream->AddMainThreadListener(this);
 }
 OscillatorNode::~OscillatorNode()
 {
 }
 size_t
 OscillatorNode::SizeOfExcludingThis(MallocSizeOf aMallocSizeOf) const
 {
   size_t amount = AudioNode::SizeOfExcludingThis(aMallocSizeOf);
   // For now only report if we know for sure that it's not shared.
   amount += mPeriodicWave->SizeOfExcludingThisIfNotShared(aMallocSizeOf);
   amount += mFrequency->SizeOfIncludingThis(aMallocSizeOf);
   amount += mDetune->SizeOfIncludingThis(aMallocSizeOf);
   return amount;
 }
 size_t
 OscillatorNode::SizeOfIncludingThis(MallocSizeOf aMallocSizeOf) const
 {
   return aMallocSizeOf(this) + SizeOfExcludingThis(aMallocSizeOf);
 }
 JSObject*
 OscillatorNode::WrapObject(JSContext* aCx)
 {
   return OscillatorNodeBinding::Wrap(aCx, this);
 }
 void
 OscillatorNode::SendFrequencyToStream(AudioNode* aNode)
 {
   OscillatorNode* This = static_cast<OscillatorNode*>(aNode);
   SendTimelineParameterToStream(This, OscillatorNodeEngine::FREQUENCY, *This->mFrequency);
 }
 void
 OscillatorNode::SendDetuneToStream(AudioNode* aNode)
 {
   OscillatorNode* This = static_cast<OscillatorNode*>(aNode);
   SendTimelineParameterToStream(This, OscillatorNodeEngine::DETUNE, *This->mDetune);
 }
 void
 OscillatorNode::SendTypeToStream()
 {
   if (mType == OscillatorType::Custom) {
     // The engine assumes we'll send the custom data before updating the type.
     SendPeriodicWaveToStream();
   }
   SendInt32ParameterToStream(OscillatorNodeEngine::TYPE, static_cast<int32_t>(mType));
 }
 void OscillatorNode::SendPeriodicWaveToStream()
 {
   NS_ASSERTION(mType == OscillatorType::Custom,
                "Sending custom waveform to engine thread with non-custom type");
   AudioNodeStream* ns = static_cast<AudioNodeStream*>(mStream.get());
   MOZ_ASSERT(ns, "Missing node stream.");
   MOZ_ASSERT(mPeriodicWave, "Send called without PeriodicWave object.");
   SendInt32ParameterToStream(OscillatorNodeEngine::PERIODICWAVE,
                              mPeriodicWave->DataLength());
   nsRefPtr<ThreadSharedFloatArrayBufferList> data =
     mPeriodicWave->GetThreadSharedBuffer();
   ns->SetBuffer(data.forget());
 }
 void
 OscillatorNode::Start(double aWhen, ErrorResult& aRv)
 {
   if (!WebAudioUtils::IsTimeValid(aWhen)) {
     aRv.Throw(NS_ERROR_DOM_NOT_SUPPORTED_ERR);
     return;
   }
   if (mStartCalled) {
     aRv.Throw(NS_ERROR_DOM_INVALID_STATE_ERR);
     return;
   }
   mStartCalled = true;
   AudioNodeStream* ns = static_cast<AudioNodeStream*>(mStream.get());
   if (!ns) {
     // Nothing to play, or we're already dead for some reason
     return;
   }
   // TODO: Perhaps we need to do more here.
   ns->SetStreamTimeParameter(OscillatorNodeEngine::START,
                              Context(), aWhen);
   MarkActive();
 }
 void
 OscillatorNode::Stop(double aWhen, ErrorResult& aRv)
 {
   if (!WebAudioUtils::IsTimeValid(aWhen)) {
     aRv.Throw(NS_ERROR_DOM_NOT_SUPPORTED_ERR);
     return;
   }
   if (!mStartCalled) {
     aRv.Throw(NS_ERROR_DOM_INVALID_STATE_ERR);
     return;
   }
   AudioNodeStream* ns = static_cast<AudioNodeStream*>(mStream.get());
   if (!ns || !Context()) {
     // We've already stopped and had our stream shut down
     return;
   }
   // TODO: Perhaps we need to do more here.
   ns->SetStreamTimeParameter(OscillatorNodeEngine::STOP,
                              Context(), std::max(0.0, aWhen));
 }
 void
 OscillatorNode::NotifyMainThreadStateChanged()
 {
   if (mStream->IsFinished()) {
     class EndedEventDispatcher : public nsRunnable
     {
     public:
       explicit EndedEventDispatcher(OscillatorNode* aNode)
         : mNode(aNode) {}
       NS_IMETHODIMP Run()
       {
         // If it's not safe to run scripts right now, schedule this to run later
         if (!nsContentUtils::IsSafeToRunScript()) {
           nsContentUtils::AddScriptRunner(this);
           return NS_OK;
         }
         mNode->DispatchTrustedEvent(NS_LITERAL_STRING("ended"));
         return NS_OK;
       }
     private:
       nsRefPtr<OscillatorNode> mNode;
     };
     if (!mStopped) {
       // Only dispatch the ended event once
       NS_DispatchToMainThread(new EndedEventDispatcher(this));
       mStopped = true;
     }
     // Drop the playing reference
     // Warning: The below line might delete this.
     MarkInactive();
   }
 }
 }
 }

The Tor Browser / annotate

content/media/webaudio/OscillatorNode.cpp@97036ab72558 (annotated)

content/media/webaudio/OscillatorNode.cpp