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

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

content/media/webaudio/AnalyserNode.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 "mozilla/dom/AnalyserNode.h"
 #include "mozilla/dom/AnalyserNodeBinding.h"
 #include "AudioNodeEngine.h"
 #include "AudioNodeStream.h"
 #include "mozilla/Mutex.h"
 #include "mozilla/PodOperations.h"
 namespace mozilla {
 namespace dom {
 NS_IMPL_ISUPPORTS_INHERITED0(AnalyserNode, AudioNode)
 class AnalyserNodeEngine : public AudioNodeEngine
 {
   class TransferBuffer : public nsRunnable
   {
   public:
     TransferBuffer(AudioNodeStream* aStream,
                    const AudioChunk& aChunk)
       : mStream(aStream)
       , mChunk(aChunk)
     {
     }
     NS_IMETHOD Run()
     {
       nsRefPtr<AnalyserNode> node;
       {
         // No need to keep holding the lock for the whole duration of this
         // function, since we're holding a strong reference to it, so if
         // we can obtain the reference, we will hold the node alive in
         // this function.
         MutexAutoLock lock(mStream->Engine()->NodeMutex());
         node = static_cast<AnalyserNode*>(mStream->Engine()->Node());
       }
       if (node) {
         node->AppendChunk(mChunk);
       }
       return NS_OK;
     }
   private:
     nsRefPtr<AudioNodeStream> mStream;
     AudioChunk mChunk;
   };
 public:
   explicit AnalyserNodeEngine(AnalyserNode* aNode)
     : AudioNodeEngine(aNode)
   {
     MOZ_ASSERT(NS_IsMainThread());
   }
   virtual void ProcessBlock(AudioNodeStream* aStream,
                             const AudioChunk& aInput,
                             AudioChunk* aOutput,
                             bool* aFinished) MOZ_OVERRIDE
   {
     *aOutput = aInput;
     MutexAutoLock lock(NodeMutex());
     if (Node() &&
         aInput.mChannelData.Length() > 0) {
       nsRefPtr<TransferBuffer> transfer = new TransferBuffer(aStream, aInput);
       NS_DispatchToMainThread(transfer);
     }
   }
   virtual size_t SizeOfIncludingThis(MallocSizeOf aMallocSizeOf) const MOZ_OVERRIDE
   {
     return aMallocSizeOf(this) + SizeOfExcludingThis(aMallocSizeOf);
   }
 };
 AnalyserNode::AnalyserNode(AudioContext* aContext)
   : AudioNode(aContext,
 ,
               ChannelCountMode::Explicit,
               ChannelInterpretation::Speakers)
   , mAnalysisBlock(2048)
   , mMinDecibels(-100.)
   , mMaxDecibels(-30.)
   , mSmoothingTimeConstant(.8)
   , mWriteIndex(0)
 {
   mStream = aContext->Graph()->CreateAudioNodeStream(new AnalyserNodeEngine(this),
                                                      MediaStreamGraph::INTERNAL_STREAM);
   AllocateBuffer();
 }
 size_t
 AnalyserNode::SizeOfExcludingThis(MallocSizeOf aMallocSizeOf) const
 {
   size_t amount = AudioNode::SizeOfExcludingThis(aMallocSizeOf);
   amount += mAnalysisBlock.SizeOfExcludingThis(aMallocSizeOf);
   amount += mBuffer.SizeOfExcludingThis(aMallocSizeOf);
   amount += mOutputBuffer.SizeOfExcludingThis(aMallocSizeOf);
   return amount;
 }
 size_t
 AnalyserNode::SizeOfIncludingThis(MallocSizeOf aMallocSizeOf) const
 {
   return aMallocSizeOf(this) + SizeOfExcludingThis(aMallocSizeOf);
 }
 JSObject*
 AnalyserNode::WrapObject(JSContext* aCx)
 {
   return AnalyserNodeBinding::Wrap(aCx, this);
 }
 void
 AnalyserNode::SetFftSize(uint32_t aValue, ErrorResult& aRv)
 {
   // Disallow values that are not a power of 2 and outside the [32,2048] range
   if (aValue < 32 ||
       aValue > 2048 ||
       (aValue & (aValue - 1)) != 0) {
     aRv.Throw(NS_ERROR_DOM_INDEX_SIZE_ERR);
     return;
   }
   if (FftSize() != aValue) {
     mAnalysisBlock.SetFFTSize(aValue);
     AllocateBuffer();
   }
 }
 void
 AnalyserNode::SetMinDecibels(double aValue, ErrorResult& aRv)
 {
   if (aValue >= mMaxDecibels) {
     aRv.Throw(NS_ERROR_DOM_INDEX_SIZE_ERR);
     return;
   }
   mMinDecibels = aValue;
 }
 void
 AnalyserNode::SetMaxDecibels(double aValue, ErrorResult& aRv)
 {
   if (aValue <= mMinDecibels) {
     aRv.Throw(NS_ERROR_DOM_INDEX_SIZE_ERR);
     return;
   }
   mMaxDecibels = aValue;
 }
 void
 AnalyserNode::SetSmoothingTimeConstant(double aValue, ErrorResult& aRv)
 {
   if (aValue < 0 || aValue > 1) {
     aRv.Throw(NS_ERROR_DOM_INDEX_SIZE_ERR);
     return;
   }
   mSmoothingTimeConstant = aValue;
 }
 void
 AnalyserNode::GetFloatFrequencyData(const Float32Array& aArray)
 {
   if (!FFTAnalysis()) {
     // Might fail to allocate memory
     return;
   }
   aArray.ComputeLengthAndData();
   float* buffer = aArray.Data();
   uint32_t length = std::min(aArray.Length(), mOutputBuffer.Length());
   for (uint32_t i = 0; i < length; ++i) {
     buffer[i] = WebAudioUtils::ConvertLinearToDecibels(mOutputBuffer[i], mMinDecibels);
   }
 }
 void
 AnalyserNode::GetByteFrequencyData(const Uint8Array& aArray)
 {
   if (!FFTAnalysis()) {
     // Might fail to allocate memory
     return;
   }
   const double rangeScaleFactor = 1.0 / (mMaxDecibels - mMinDecibels);
   aArray.ComputeLengthAndData();
   unsigned char* buffer = aArray.Data();
   uint32_t length = std::min(aArray.Length(), mOutputBuffer.Length());
   for (uint32_t i = 0; i < length; ++i) {
     const double decibels = WebAudioUtils::ConvertLinearToDecibels(mOutputBuffer[i], mMinDecibels);
     // scale down the value to the range of [0, UCHAR_MAX]
     const double scaled = std::max(0.0, std::min(double(UCHAR_MAX),
                                                  UCHAR_MAX * (decibels - mMinDecibels) * rangeScaleFactor));
     buffer[i] = static_cast<unsigned char>(scaled);
   }
 }
 void
 AnalyserNode::GetFloatTimeDomainData(const Float32Array& aArray)
 {
   aArray.ComputeLengthAndData();
   float* buffer = aArray.Data();
   uint32_t length = std::min(aArray.Length(), mBuffer.Length());
   for (uint32_t i = 0; i < length; ++i) {
     buffer[i] = mBuffer[(i + mWriteIndex) % mBuffer.Length()];;
   }
 }
 void
 AnalyserNode::GetByteTimeDomainData(const Uint8Array& aArray)
 {
   aArray.ComputeLengthAndData();
   unsigned char* buffer = aArray.Data();
   uint32_t length = std::min(aArray.Length(), mBuffer.Length());
   for (uint32_t i = 0; i < length; ++i) {
     const float value = mBuffer[(i + mWriteIndex) % mBuffer.Length()];
     // scale the value to the range of [0, UCHAR_MAX]
     const float scaled = std::max(0.0f, std::min(float(UCHAR_MAX),
 .0f * (value + 1.0f)));
     buffer[i] = static_cast<unsigned char>(scaled);
   }
 }
 bool
 AnalyserNode::FFTAnalysis()
 {
   float* inputBuffer;
   bool allocated = false;
   if (mWriteIndex == 0) {
     inputBuffer = mBuffer.Elements();
   } else {
     inputBuffer = static_cast<float*>(moz_malloc(FftSize() * sizeof(float)));
     if (!inputBuffer) {
       return false;
     }
     memcpy(inputBuffer, mBuffer.Elements() + mWriteIndex, sizeof(float) * (FftSize() - mWriteIndex));
     memcpy(inputBuffer + FftSize() - mWriteIndex, mBuffer.Elements(), sizeof(float) * mWriteIndex);
     allocated = true;
   }
   ApplyBlackmanWindow(inputBuffer, FftSize());
   mAnalysisBlock.PerformFFT(inputBuffer);
   // Normalize so than an input sine wave at 0dBfs registers as 0dBfs (undo FFT scaling factor).
   const double magnitudeScale = 1.0 / FftSize();
   for (uint32_t i = 0; i < mOutputBuffer.Length(); ++i) {
     double scalarMagnitude = NS_hypot(mAnalysisBlock.RealData(i),
                                       mAnalysisBlock.ImagData(i)) *
                              magnitudeScale;
     mOutputBuffer[i] = mSmoothingTimeConstant * mOutputBuffer[i] +
                        (1.0 - mSmoothingTimeConstant) * scalarMagnitude;
   }
   if (allocated) {
     moz_free(inputBuffer);
   }
   return true;
 }
 void
 AnalyserNode::ApplyBlackmanWindow(float* aBuffer, uint32_t aSize)
 {
   double alpha = 0.16;
   double a0 = 0.5 * (1.0 - alpha);
   double a1 = 0.5;
   double a2 = 0.5 * alpha;
   for (uint32_t i = 0; i < aSize; ++i) {
     double x = double(i) / aSize;
     double window = a0 - a1 * cos(2 * M_PI * x) + a2 * cos(4 * M_PI * x);
     aBuffer[i] *= window;
   }
 }
 bool
 AnalyserNode::AllocateBuffer()
 {
   bool result = true;
   if (mBuffer.Length() != FftSize()) {
     result = mBuffer.SetLength(FftSize());
     if (result) {
       memset(mBuffer.Elements(), 0, sizeof(float) * FftSize());
       mWriteIndex = 0;
       result = mOutputBuffer.SetLength(FrequencyBinCount());
       if (result) {
         memset(mOutputBuffer.Elements(), 0, sizeof(float) * FrequencyBinCount());
       }
     }
   }
   return result;
 }
 void
 AnalyserNode::AppendChunk(const AudioChunk& aChunk)
 {
   const uint32_t bufferSize = mBuffer.Length();
   const uint32_t channelCount = aChunk.mChannelData.Length();
   uint32_t chunkDuration = aChunk.mDuration;
   MOZ_ASSERT((bufferSize & (bufferSize - 1)) == 0); // Must be a power of two!
   MOZ_ASSERT(channelCount > 0);
   MOZ_ASSERT(chunkDuration == WEBAUDIO_BLOCK_SIZE);
   if (chunkDuration > bufferSize) {
     // Copy a maximum bufferSize samples.
     chunkDuration = bufferSize;
   }
   PodCopy(mBuffer.Elements() + mWriteIndex, static_cast<const float*>(aChunk.mChannelData[0]), chunkDuration);
   for (uint32_t i = 1; i < channelCount; ++i) {
     AudioBlockAddChannelWithScale(static_cast<const float*>(aChunk.mChannelData[i]), 1.0f,
                                   mBuffer.Elements() + mWriteIndex);
   }
   if (channelCount > 1) {
     AudioBlockInPlaceScale(mBuffer.Elements() + mWriteIndex,
 .0f / aChunk.mChannelData.Length());
   }
   mWriteIndex += chunkDuration;
   MOZ_ASSERT(mWriteIndex <= bufferSize);
   if (mWriteIndex >= bufferSize) {
     mWriteIndex = 0;
   }
 }
 }
 }

The Tor Browser / annotate

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

content/media/webaudio/AnalyserNode.cpp