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 /*

  * Copyright (C) 2010 Google Inc. All rights reserved.

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 #include "ReverbConvolver.h"

 #include "ReverbConvolverStage.h"

 using namespace mozilla;

 template<>

 struct RunnableMethodTraits<WebCore::ReverbConvolver>

 {

   static void RetainCallee(WebCore::ReverbConvolver* obj) {}

   static void ReleaseCallee(WebCore::ReverbConvolver* obj) {}

 };

 namespace WebCore {

 const int InputBufferSize = 8 * 16384;

 // We only process the leading portion of the impulse response in the real-time thread.  We don't exceed this length.

 // It turns out then, that the background thread has about 278msec of scheduling slop.

 // Empirically, this has been found to be a good compromise between giving enough time for scheduling slop,

 // while still minimizing the amount of processing done in the primary (high-priority) thread.

 // This was found to be a good value on Mac OS X, and may work well on other platforms as well, assuming

 // the very rough scheduling latencies are similar on these time-scales.  Of course, this code may need to be

 // tuned for individual platforms if this assumption is found to be incorrect.

 const size_t RealtimeFrameLimit = 8192  + 4096; // ~278msec @ 44.1KHz

 const size_t MinFFTSize = 128;

 const size_t MaxRealtimeFFTSize = 2048;

 ReverbConvolver::ReverbConvolver(const float* impulseResponseData, size_t impulseResponseLength, size_t renderSliceSize, size_t maxFFTSize, size_t convolverRenderPhase, bool useBackgroundThreads)

     : m_impulseResponseLength(impulseResponseLength)

     , m_accumulationBuffer(impulseResponseLength + renderSliceSize)

     , m_inputBuffer(InputBufferSize)

     , m_minFFTSize(MinFFTSize) // First stage will have this size - successive stages will double in size each time

     , m_maxFFTSize(maxFFTSize) // until we hit m_maxFFTSize

     , m_backgroundThread("ConvolverWorker")

     , m_backgroundThreadCondition(&m_backgroundThreadLock)

     , m_useBackgroundThreads(useBackgroundThreads)

     , m_wantsToExit(false)

     , m_moreInputBuffered(false)

 {

     // If we are using background threads then don't exceed this FFT size for the

     // stages which run in the real-time thread.  This avoids having only one or two

     // large stages (size 16384 or so) at the end which take a lot of time every several

     // processing slices.  This way we amortize the cost over more processing slices.

     m_maxRealtimeFFTSize = MaxRealtimeFFTSize;

     // For the moment, a good way to know if we have real-time constraint is to check if we're using background threads.

     // Otherwise, assume we're being run from a command-line tool.

     bool hasRealtimeConstraint = useBackgroundThreads;

     const float* response = impulseResponseData;

     size_t totalResponseLength = impulseResponseLength;

     // The total latency is zero because the direct-convolution is used in the leading portion.

     size_t reverbTotalLatency = 0;

     size_t stageOffset = 0;

     int i = 0;

     size_t fftSize = m_minFFTSize;

     while (stageOffset < totalResponseLength) {

         size_t stageSize = fftSize / 2;

         // For the last stage, it's possible that stageOffset is such that we're straddling the end

         // of the impulse response buffer (if we use stageSize), so reduce the last stage's length...

         if (stageSize + stageOffset > totalResponseLength)

             stageSize = totalResponseLength - stageOffset;

         // This "staggers" the time when each FFT happens so they don't all happen at the same time

         int renderPhase = convolverRenderPhase + i * renderSliceSize;

         bool useDirectConvolver = !stageOffset;

         nsAutoPtr<ReverbConvolverStage> stage(new ReverbConvolverStage(response, totalResponseLength, reverbTotalLatency, stageOffset, stageSize, fftSize, renderPhase, renderSliceSize, &m_accumulationBuffer, useDirectConvolver));

         bool isBackgroundStage = false;

         if (this->useBackgroundThreads() && stageOffset > RealtimeFrameLimit) {

             m_backgroundStages.AppendElement(stage.forget());

             isBackgroundStage = true;

         } else

             m_stages.AppendElement(stage.forget());

         stageOffset += stageSize;

         ++i;

         if (!useDirectConvolver) {

             // Figure out next FFT size

             fftSize *= 2;

         }

         if (hasRealtimeConstraint && !isBackgroundStage && fftSize > m_maxRealtimeFFTSize)

             fftSize = m_maxRealtimeFFTSize;

         if (fftSize > m_maxFFTSize)

             fftSize = m_maxFFTSize;

     }

     // Start up background thread

     // FIXME: would be better to up the thread priority here.  It doesn't need to be real-time, but higher than the default...

     if (this->useBackgroundThreads() && m_backgroundStages.Length() > 0) {

         if (!m_backgroundThread.Start()) {

           NS_WARNING("Cannot start convolver thread.");

           return;

         }

         CancelableTask* task = NewRunnableMethod(this, &ReverbConvolver::backgroundThreadEntry);

         m_backgroundThread.message_loop()->PostTask(FROM_HERE, task);

     }

 }

 ReverbConvolver::~ReverbConvolver()

 {

     // Wait for background thread to stop

     if (useBackgroundThreads() && m_backgroundThread.IsRunning()) {

         m_wantsToExit = true;

         // Wake up thread so it can return

         {

             AutoLock locker(m_backgroundThreadLock);

             m_moreInputBuffered = true;

             m_backgroundThreadCondition.Signal();

         }

         m_backgroundThread.Stop();

     }

 }

 size_t ReverbConvolver::sizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf) const

 {

     size_t amount = aMallocSizeOf(this);

     amount += m_stages.SizeOfExcludingThis(aMallocSizeOf);

     for (size_t i = 0; i < m_stages.Length(); i++) {

         if (m_stages[i]) {

             amount += m_stages[i]->sizeOfIncludingThis(aMallocSizeOf);

         }

     }

     amount += m_backgroundStages.SizeOfExcludingThis(aMallocSizeOf);

     for (size_t i = 0; i < m_backgroundStages.Length(); i++) {

         if (m_backgroundStages[i]) {

             amount += m_backgroundStages[i]->sizeOfIncludingThis(aMallocSizeOf);

         }

     }

     // NB: The buffer sizes are static, so even though they might be accessed

     //     in another thread it's safe to measure them.

     amount += m_accumulationBuffer.sizeOfExcludingThis(aMallocSizeOf);

     amount += m_inputBuffer.sizeOfExcludingThis(aMallocSizeOf);

     // Possible future measurements:

     // - m_backgroundThread

     // - m_backgroundThreadLock

     // - m_backgroundThreadCondition

     return amount;

 }

 void ReverbConvolver::backgroundThreadEntry()

 {

     while (!m_wantsToExit) {

         // Wait for realtime thread to give us more input

         m_moreInputBuffered = false;

         {

             AutoLock locker(m_backgroundThreadLock);

             while (!m_moreInputBuffered && !m_wantsToExit)

                 m_backgroundThreadCondition.Wait();

         }

         // Process all of the stages until their read indices reach the input buffer's write index

         int writeIndex = m_inputBuffer.writeIndex();

         // Even though it doesn't seem like every stage needs to maintain its own version of readIndex 

         // we do this in case we want to run in more than one background thread.

         int readIndex;

         while ((readIndex = m_backgroundStages[0]->inputReadIndex()) != writeIndex) { // FIXME: do better to detect buffer overrun...

             // The ReverbConvolverStages need to process in amounts which evenly divide half the FFT size

             const int SliceSize = MinFFTSize / 2;

             // Accumulate contributions from each stage

             for (size_t i = 0; i < m_backgroundStages.Length(); ++i)

                 m_backgroundStages[i]->processInBackground(this, SliceSize);

         }

     }

 }

 void ReverbConvolver::process(const float* sourceChannelData, size_t sourceChannelLength,

                               float* destinationChannelData, size_t destinationChannelLength,

                               size_t framesToProcess)

 {

     bool isSafe = sourceChannelData && destinationChannelData && sourceChannelLength >= framesToProcess && destinationChannelLength >= framesToProcess;

     MOZ_ASSERT(isSafe);

     if (!isSafe)

         return;

     const float* source = sourceChannelData;

     float* destination = destinationChannelData;

     bool isDataSafe = source && destination;

     MOZ_ASSERT(isDataSafe);

     if (!isDataSafe)

         return;

     // Feed input buffer (read by all threads)

     m_inputBuffer.write(source, framesToProcess);

     // Accumulate contributions from each stage

     for (size_t i = 0; i < m_stages.Length(); ++i)

         m_stages[i]->process(source, framesToProcess);

     // Finally read from accumulation buffer

     m_accumulationBuffer.readAndClear(destination, framesToProcess);

     // Now that we've buffered more input, wake up our background thread.

     // Not using a MutexLocker looks strange, but we use a tryLock() instead because this is run on the real-time

     // thread where it is a disaster for the lock to be contended (causes audio glitching).  It's OK if we fail to

     // signal from time to time, since we'll get to it the next time we're called.  We're called repeatedly

     // and frequently (around every 3ms).  The background thread is processing well into the future and has a considerable amount of 

     // leeway here...

     if (m_backgroundThreadLock.Try()) {

         m_moreInputBuffered = true;

         m_backgroundThreadCondition.Signal();

         m_backgroundThreadLock.Release();

     }

 }

 void ReverbConvolver::reset()

 {

     for (size_t i = 0; i < m_stages.Length(); ++i)

         m_stages[i]->reset();

     for (size_t i = 0; i < m_backgroundStages.Length(); ++i)

         m_backgroundStages[i]->reset();

     m_accumulationBuffer.reset();

     m_inputBuffer.reset();

 }

 size_t ReverbConvolver::latencyFrames() const

 {

     return 0;

 }

 } // namespace WebCore