diff -r 000000000000 -r 6474c204b198 content/media/webaudio/blink/FFTConvolver.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/content/media/webaudio/blink/FFTConvolver.cpp	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,132 @@
+/*
+ * Copyright (C) 2010 Google Inc. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1.  Redistributions of source code must retain the above copyright
+ *     notice, this list of conditions and the following disclaimer.
+ * 2.  Redistributions in binary form must reproduce the above copyright
+ *     notice, this list of conditions and the following disclaimer in the
+ *     documentation and/or other materials provided with the distribution.
+ * 3.  Neither the name of Apple Computer, Inc. ("Apple") nor the names of
+ *     its contributors may be used to endorse or promote products derived
+ *     from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
+ * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
+ * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "FFTConvolver.h"
+#include "mozilla/PodOperations.h"
+
+using namespace mozilla;
+
+namespace WebCore {
+
+FFTConvolver::FFTConvolver(size_t fftSize)
+    : m_frame(fftSize)
+    , m_readWriteIndex(0)
+{
+  m_inputBuffer.SetLength(fftSize);
+  PodZero(m_inputBuffer.Elements(), fftSize);
+  m_outputBuffer.SetLength(fftSize);
+  PodZero(m_outputBuffer.Elements(), fftSize);
+  m_lastOverlapBuffer.SetLength(fftSize / 2);
+  PodZero(m_lastOverlapBuffer.Elements(), fftSize / 2);
+}
+
+size_t FFTConvolver::sizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const
+{
+    size_t amount = 0;
+    amount += m_frame.SizeOfExcludingThis(aMallocSizeOf);
+    amount += m_inputBuffer.SizeOfExcludingThis(aMallocSizeOf);
+    amount += m_outputBuffer.SizeOfExcludingThis(aMallocSizeOf);
+    amount += m_lastOverlapBuffer.SizeOfExcludingThis(aMallocSizeOf);
+    return amount;
+}
+
+size_t FFTConvolver::sizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf) const
+{
+  return aMallocSizeOf(this) + sizeOfExcludingThis(aMallocSizeOf);
+}
+
+void FFTConvolver::process(FFTBlock* fftKernel, const float* sourceP, float* destP, size_t framesToProcess)
+{
+    size_t halfSize = fftSize() / 2;
+
+    // framesToProcess must be an exact multiple of halfSize,
+    // or halfSize is a multiple of framesToProcess when halfSize > framesToProcess.
+    bool isGood = !(halfSize % framesToProcess && framesToProcess % halfSize);
+    MOZ_ASSERT(isGood);
+    if (!isGood)
+        return;
+
+    size_t numberOfDivisions = halfSize <= framesToProcess ? (framesToProcess / halfSize) : 1;
+    size_t divisionSize = numberOfDivisions == 1 ? framesToProcess : halfSize;
+
+    for (size_t i = 0; i < numberOfDivisions; ++i, sourceP += divisionSize, destP += divisionSize) {
+        // Copy samples to input buffer (note contraint above!)
+        float* inputP = m_inputBuffer.Elements();
+
+        // Sanity check
+        bool isCopyGood1 = sourceP && inputP && m_readWriteIndex + divisionSize <= m_inputBuffer.Length();
+        MOZ_ASSERT(isCopyGood1);
+        if (!isCopyGood1)
+            return;
+
+        memcpy(inputP + m_readWriteIndex, sourceP, sizeof(float) * divisionSize);
+
+        // Copy samples from output buffer
+        float* outputP = m_outputBuffer.Elements();
+
+        // Sanity check
+        bool isCopyGood2 = destP && outputP && m_readWriteIndex + divisionSize <= m_outputBuffer.Length();
+        MOZ_ASSERT(isCopyGood2);
+        if (!isCopyGood2)
+            return;
+
+        memcpy(destP, outputP + m_readWriteIndex, sizeof(float) * divisionSize);
+        m_readWriteIndex += divisionSize;
+
+        // Check if it's time to perform the next FFT
+        if (m_readWriteIndex == halfSize) {
+            // The input buffer is now filled (get frequency-domain version)
+            m_frame.PerformFFT(m_inputBuffer.Elements());
+            m_frame.Multiply(*fftKernel);
+            m_frame.GetInverseWithoutScaling(m_outputBuffer.Elements());
+
+            // Overlap-add 1st half from previous time
+            AudioBufferAddWithScale(m_lastOverlapBuffer.Elements(), 1.0f,
+                                    m_outputBuffer.Elements(), halfSize);
+
+            // Finally, save 2nd half of result
+            bool isCopyGood3 = m_outputBuffer.Length() == 2 * halfSize && m_lastOverlapBuffer.Length() == halfSize;
+            MOZ_ASSERT(isCopyGood3);
+            if (!isCopyGood3)
+                return;
+
+            memcpy(m_lastOverlapBuffer.Elements(), m_outputBuffer.Elements() + halfSize, sizeof(float) * halfSize);
+
+            // Reset index back to start for next time
+            m_readWriteIndex = 0;
+        }
+    }
+}
+
+void FFTConvolver::reset()
+{
+    PodZero(m_lastOverlapBuffer.Elements(), m_lastOverlapBuffer.Length());
+    m_readWriteIndex = 0;
+}
+
+} // namespace WebCore