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      1 /*
      2  * Copyright (C) 2010, Google Inc. All rights reserved.
      3  *
      4  * Redistribution and use in source and binary forms, with or without
      5  * modification, are permitted provided that the following conditions
      6  * are met:
      7  * 1.  Redistributions of source code must retain the above copyright
      8  *    notice, this list of conditions and the following disclaimer.
      9  * 2.  Redistributions in binary form must reproduce the above copyright
     10  *    notice, this list of conditions and the following disclaimer in the
     11  *    documentation and/or other materials provided with the distribution.
     12  *
     13  * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS'' AND ANY
     14  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
     15  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
     16  * DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS BE LIABLE FOR ANY
     17  * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
     18  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
     19  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
     20  * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     21  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
     22  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     23  */
     24 
     25 #include "config.h"
     26 
     27 #if ENABLE(WEB_AUDIO)
     28 
     29 #include "core/platform/audio/AudioResampler.h"
     30 
     31 #include <algorithm>
     32 #include "core/platform/audio/AudioBus.h"
     33 #include "wtf/MathExtras.h"
     34 
     35 using namespace std;
     36 
     37 namespace WebCore {
     38 
     39 const double AudioResampler::MaxRate = 8.0;
     40 
     41 AudioResampler::AudioResampler()
     42     : m_rate(1.0)
     43 {
     44     m_kernels.append(adoptPtr(new AudioResamplerKernel(this)));
     45     m_sourceBus = AudioBus::create(1, 0, false);
     46 }
     47 
     48 AudioResampler::AudioResampler(unsigned numberOfChannels)
     49     : m_rate(1.0)
     50 {
     51     for (unsigned i = 0; i < numberOfChannels; ++i)
     52         m_kernels.append(adoptPtr(new AudioResamplerKernel(this)));
     53 
     54     m_sourceBus = AudioBus::create(numberOfChannels, 0, false);
     55 }
     56 
     57 void AudioResampler::configureChannels(unsigned numberOfChannels)
     58 {
     59     unsigned currentSize = m_kernels.size();
     60     if (numberOfChannels == currentSize)
     61         return; // already setup
     62 
     63     // First deal with adding or removing kernels.
     64     if (numberOfChannels > currentSize) {
     65         for (unsigned i = currentSize; i < numberOfChannels; ++i)
     66             m_kernels.append(adoptPtr(new AudioResamplerKernel(this)));
     67     } else
     68         m_kernels.resize(numberOfChannels);
     69 
     70     // Reconfigure our source bus to the new channel size.
     71     m_sourceBus = AudioBus::create(numberOfChannels, 0, false);
     72 }
     73 
     74 void AudioResampler::process(AudioSourceProvider* provider, AudioBus* destinationBus, size_t framesToProcess)
     75 {
     76     ASSERT(provider);
     77     if (!provider)
     78         return;
     79 
     80     unsigned numberOfChannels = m_kernels.size();
     81 
     82     // Make sure our configuration matches the bus we're rendering to.
     83     bool channelsMatch = (destinationBus && destinationBus->numberOfChannels() == numberOfChannels);
     84     ASSERT(channelsMatch);
     85     if (!channelsMatch)
     86         return;
     87 
     88     // Setup the source bus.
     89     for (unsigned i = 0; i < numberOfChannels; ++i) {
     90         // Figure out how many frames we need to get from the provider, and a pointer to the buffer.
     91         size_t framesNeeded;
     92         float* fillPointer = m_kernels[i]->getSourcePointer(framesToProcess, &framesNeeded);
     93         ASSERT(fillPointer);
     94         if (!fillPointer)
     95             return;
     96 
     97         m_sourceBus->setChannelMemory(i, fillPointer, framesNeeded);
     98     }
     99 
    100     // Ask the provider to supply the desired number of source frames.
    101     provider->provideInput(m_sourceBus.get(), m_sourceBus->length());
    102 
    103     // Now that we have the source data, resample each channel into the destination bus.
    104     // FIXME: optimize for the common stereo case where it's faster to process both left/right channels in the same inner loop.
    105     for (unsigned i = 0; i < numberOfChannels; ++i) {
    106         float* destination = destinationBus->channel(i)->mutableData();
    107         m_kernels[i]->process(destination, framesToProcess);
    108     }
    109 }
    110 
    111 void AudioResampler::setRate(double rate)
    112 {
    113     if (std::isnan(rate) || std::isinf(rate) || rate <= 0.0)
    114         return;
    115 
    116     m_rate = min(AudioResampler::MaxRate, rate);
    117 }
    118 
    119 void AudioResampler::reset()
    120 {
    121     unsigned numberOfChannels = m_kernels.size();
    122     for (unsigned i = 0; i < numberOfChannels; ++i)
    123         m_kernels[i]->reset();
    124 }
    125 
    126 } // namespace WebCore
    127 
    128 #endif // ENABLE(WEB_AUDIO)
    129