1 files changed, 110 insertions, 0 deletions
diff --git a/Source/WebCore/platform/audio/FFTConvolver.cpp b/Source/WebCore/platform/audio/FFTConvolver.cpp
new file mode 100644
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+++ b/Source/WebCore/platform/audio/FFTConvolver.cpp
@@ -0,0 +1,110 @@
+/*
+ * 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 "config.h"
+
+#if ENABLE(WEB_AUDIO)
+
+#include "FFTConvolver.h"
+
+#include "VectorMath.h"
+
+namespace WebCore {
+
+using namespace VectorMath;
+    
+FFTConvolver::FFTConvolver(size_t fftSize)
+    : m_frame(fftSize)
+    , m_readWriteIndex(0)
+    , m_inputBuffer(fftSize) // 2nd half of buffer is always zeroed
+    , m_outputBuffer(fftSize)
+    , m_lastOverlapBuffer(fftSize / 2)
+{
+}
+
+void FFTConvolver::process(FFTFrame* fftKernel, float* sourceP, float* destP, size_t framesToProcess)
+{
+    // FIXME: make so framesToProcess is not required to fit evenly into fftSize/2
+
+    // Copy samples to input buffer (note contraint above!)
+    float* inputP = m_inputBuffer.data();
+
+    // Sanity check
+    bool isCopyGood1 = sourceP && inputP && m_readWriteIndex + framesToProcess <= m_inputBuffer.size();
+    ASSERT(isCopyGood1);
+    if (!isCopyGood1)
+        return;
+    
+    memcpy(inputP + m_readWriteIndex, sourceP, sizeof(float) * framesToProcess);
+
+    // Copy samples from output buffer
+    float* outputP = m_outputBuffer.data();
+
+    // Sanity check
+    bool isCopyGood2 = destP && outputP && m_readWriteIndex + framesToProcess <= m_outputBuffer.size();
+    ASSERT(isCopyGood2);
+    if (!isCopyGood2)
+        return;
+
+    memcpy(destP, outputP + m_readWriteIndex, sizeof(float) * framesToProcess);
+    m_readWriteIndex += framesToProcess;
+
+
+    // Check if it's time to perform the next FFT
+    size_t halfSize = fftSize() / 2;
+    if (m_readWriteIndex == halfSize) {
+        // The input buffer is now filled (get frequency-domain version)
+        m_frame.doFFT(m_inputBuffer.data());
+        m_frame.multiply(*fftKernel);
+        m_frame.doInverseFFT(m_outputBuffer.data());
+
+        // Overlap-add 1st half from previous time
+        vadd(m_outputBuffer.data(), 1, m_lastOverlapBuffer.data(), 1, m_outputBuffer.data(), 1, halfSize);
+
+        // Finally, save 2nd half of result
+        bool isCopyGood3 = m_outputBuffer.size() == 2 * halfSize && m_lastOverlapBuffer.size() == halfSize;
+        ASSERT(isCopyGood3);
+        if (!isCopyGood3)
+            return;
+        
+        memcpy(m_lastOverlapBuffer.data(), m_outputBuffer.data() + halfSize, sizeof(float) * halfSize);
+
+        // Reset index back to start for next time
+        m_readWriteIndex = 0;
+    }
+}
+
+void FFTConvolver::reset()
+{
+    m_lastOverlapBuffer.zero();
+    m_readWriteIndex = 0;
+}
+
+} // namespace WebCore
+
+#endif // ENABLE(WEB_AUDIO)