1 files changed, 128 insertions, 0 deletions
diff --git a/WebCore/platform/audio/AudioResampler.cpp b/WebCore/platform/audio/AudioResampler.cpp
new file mode 100644
index 0000000..7f8221e
--- /dev/null
+++ b/WebCore/platform/audio/AudioResampler.cpp
@@ -0,0 +1,128 @@
+/*
+ * 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.
+ *
+ * THIS SOFTWARE IS PROVIDED BY APPLE INC. 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 INC. 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 "AudioResampler.h"
+
+#include "AudioBus.h"
+#include <algorithm>
+#include <math.h>
+
+using namespace std;
+ 
+namespace WebCore {
+
+const double AudioResampler::MaxRate = 8.0;
+
+AudioResampler::AudioResampler()
+    : m_rate(1.0)
+{
+    m_kernels.append(adoptPtr(new AudioResamplerKernel(this)));
+    m_sourceBus = adoptPtr(new AudioBus(1, 0, false));
+}
+
+AudioResampler::AudioResampler(unsigned numberOfChannels)
+    : m_rate(1.0)
+{
+    for (unsigned i = 0; i < numberOfChannels; ++i)
+        m_kernels.append(adoptPtr(new AudioResamplerKernel(this)));
+
+    m_sourceBus = adoptPtr(new AudioBus(numberOfChannels, 0, false));
+}
+
+void AudioResampler::configureChannels(unsigned numberOfChannels)
+{
+    unsigned currentSize = m_kernels.size();
+    if (numberOfChannels == currentSize)
+        return; // already setup
+
+    // First deal with adding or removing kernels.
+    if (numberOfChannels > currentSize) {
+        for (unsigned i = currentSize; i < numberOfChannels; ++i)
+            m_kernels.append(adoptPtr(new AudioResamplerKernel(this)));
+    } else
+        m_kernels.resize(numberOfChannels);
+
+    // Reconfigure our source bus to the new channel size.
+    m_sourceBus = adoptPtr(new AudioBus(numberOfChannels, 0, false));
+}
+
+void AudioResampler::process(AudioSourceProvider* provider, AudioBus* destinationBus, size_t framesToProcess)
+{
+    ASSERT(provider);
+    if (!provider)
+        return;
+        
+    unsigned numberOfChannels = m_kernels.size();
+
+    // Make sure our configuration matches the bus we're rendering to.
+    bool channelsMatch = (destinationBus && destinationBus->numberOfChannels() == numberOfChannels);
+    ASSERT(channelsMatch);
+    if (!channelsMatch)
+        return;
+
+    // Setup the source bus.
+    for (unsigned i = 0; i < numberOfChannels; ++i) {
+        // Figure out how many frames we need to get from the provider, and a pointer to the buffer.
+        size_t framesNeeded;
+        float* fillPointer = m_kernels[i]->getSourcePointer(framesToProcess, &framesNeeded);
+        ASSERT(fillPointer);
+        if (!fillPointer)
+            return;
+            
+        m_sourceBus->setChannelMemory(i, fillPointer, framesNeeded);
+    }
+
+    // Ask the provider to supply the desired number of source frames.
+    provider->provideInput(m_sourceBus.get(), m_sourceBus->length());
+
+    // Now that we have the source data, resample each channel into the destination bus.
+    // FIXME: optimize for the common stereo case where it's faster to process both left/right channels in the same inner loop.
+    for (unsigned i = 0; i < numberOfChannels; ++i) {
+        float* destination = destinationBus->channel(i)->data();
+        m_kernels[i]->process(destination, framesToProcess);
+    }
+}
+
+void AudioResampler::setRate(double rate)
+{
+    if (isnan(rate) || isinf(rate) || rate <= 0.0)
+        return;
+    
+    m_rate = min(AudioResampler::MaxRate, rate);
+}
+
+void AudioResampler::reset()
+{
+    unsigned numberOfChannels = m_kernels.size();
+    for (unsigned i = 0; i < numberOfChannels; ++i)
+        m_kernels[i]->reset();
+}
+
+} // namespace WebCore
+
+#endif // ENABLE(WEB_AUDIO)