Add support for WaveShaperNode.oversample

Source/core/platform/audio/UpSampler.h

Index: Source/core/platform/audio/UpSampler.h
diff --git a/Source/core/platform/audio/DirectConvolver.h b/Source/core/platform/audio/UpSampler.h
similarity index 63%
copy from Source/core/platform/audio/DirectConvolver.h
copy to Source/core/platform/audio/UpSampler.h
index 0528d7cb6ce66e12fdcfda6cd25da8ed98f32ebf..1b1287a88dd4e0ea4a9b4c040e25537ad3381364 100644
--- a/Source/core/platform/audio/DirectConvolver.h
+++ b/Source/core/platform/audio/UpSampler.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2012 Intel Inc. All rights reserved.
+ * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -26,34 +26,45 @@
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-#ifndef DirectConvolver_h
-#define DirectConvolver_h
+#ifndef UpSampler_h
+#define UpSampler_h
 
 #include "core/platform/audio/AudioArray.h"
-
-#if USE(WEBAUDIO_IPP)
-#include <ipps.h>
-#endif // USE(WEBAUDIO_IPP)
+#include "core/platform/audio/DirectConvolver.h"
 
 namespace WebCore {
 
-class DirectConvolver {
+// UpSampler up-samples the source stream by a factor of 2x.
+
+class UpSampler {
 public:
-    DirectConvolver(size_t inputBlockSize);
+    UpSampler(size_t inputBlockSize);
 
-    void process(AudioFloatArray* convolutionKernel, const float* sourceP, float* destP, size_t framesToProcess);
+    // The destination buffer |destP| is of size sourceFramesToProcess * 2.
+    void process(const float* sourceP, float* destP, size_t sourceFramesToProcess);
 
     void reset();
 
+    // Latency based on the source sample-rate.
+    size_t latencyFrames() const;
+
 private:
+    enum { DefaultKernelSize = 128 };
+
     size_t m_inputBlockSize;
 
-#if USE(WEBAUDIO_IPP)
-    AudioFloatArray m_overlayBuffer;
-#endif // USE(WEBAUDIO_IPP)
-    AudioFloatArray m_buffer;
+    // Computes ideal band-limited filter coefficients to sample in between each source sample-frame.
+    // This filter will be used to compute the odd sample-frames of the output.
+    void initializeKernel();
+    AudioFloatArray m_kernel;
+
+    // Computes the odd sample-frames of the output.
+    DirectConvolver m_convolver;
+
+    AudioFloatArray m_tempBuffer;
+    AudioFloatArray m_inputBuffer;
 };
 
 } // namespace WebCore
 
-#endif // DirectConvolver_h
+#endif // UpSampler_h