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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 "platform/audio/AudioResampler.h"
     30 
     31 #include <algorithm>
     32 #include "wtf/MathExtras.h"
     33 
     34 using namespace std;
     35 
     36 namespace WebCore {
     37 
     38 const double AudioResampler::MaxRate = 8.0;
     39 
     40 AudioResampler::AudioResampler()
     41     : m_rate(1.0)
     42 {
     43     m_kernels.append(adoptPtr(new AudioResamplerKernel(this)));
     44     m_sourceBus = AudioBus::create(1, 0, false);
     45 }
     46 
     47 AudioResampler::AudioResampler(unsigned numberOfChannels)
     48     : m_rate(1.0)
     49 {
     50     for (unsigned i = 0; i < numberOfChannels; ++i)
     51         m_kernels.append(adoptPtr(new AudioResamplerKernel(this)));
     52 
     53     m_sourceBus = AudioBus::create(numberOfChannels, 0, false);
     54 }
     55 
     56 void AudioResampler::configureChannels(unsigned numberOfChannels)
     57 {
     58     unsigned currentSize = m_kernels.size();
     59     if (numberOfChannels == currentSize)
     60         return; // already setup
     61 
     62     // First deal with adding or removing kernels.
     63     if (numberOfChannels > currentSize) {
     64         for (unsigned i = currentSize; i < numberOfChannels; ++i)
     65             m_kernels.append(adoptPtr(new AudioResamplerKernel(this)));
     66     } else
     67         m_kernels.resize(numberOfChannels);
     68 
     69     // Reconfigure our source bus to the new channel size.
     70     m_sourceBus = AudioBus::create(numberOfChannels, 0, false);
     71 }
     72 
     73 void AudioResampler::process(AudioSourceProvider* provider, AudioBus* destinationBus, size_t framesToProcess)
     74 {
     75     ASSERT(provider);
     76     if (!provider)
     77         return;
     78 
     79     unsigned numberOfChannels = m_kernels.size();
     80 
     81     // Make sure our configuration matches the bus we're rendering to.
     82     bool channelsMatch = (destinationBus && destinationBus->numberOfChannels() == numberOfChannels);
     83     ASSERT(channelsMatch);
     84     if (!channelsMatch)
     85         return;
     86 
     87     // Setup the source bus.
     88     for (unsigned i = 0; i < numberOfChannels; ++i) {
     89         // Figure out how many frames we need to get from the provider, and a pointer to the buffer.
     90         size_t framesNeeded;
     91         float* fillPointer = m_kernels[i]->getSourcePointer(framesToProcess, &framesNeeded);
     92         ASSERT(fillPointer);
     93         if (!fillPointer)
     94             return;
     95 
     96         m_sourceBus->setChannelMemory(i, fillPointer, framesNeeded);
     97     }
     98 
     99     // Ask the provider to supply the desired number of source frames.
    100     provider->provideInput(m_sourceBus.get(), m_sourceBus->length());
    101 
    102     // Now that we have the source data, resample each channel into the destination bus.
    103     // FIXME: optimize for the common stereo case where it's faster to process both left/right channels in the same inner loop.
    104     for (unsigned i = 0; i < numberOfChannels; ++i) {
    105         float* destination = destinationBus->channel(i)->mutableData();
    106         m_kernels[i]->process(destination, framesToProcess);
    107     }
    108 }
    109 
    110 void AudioResampler::setRate(double rate)
    111 {
    112     if (std::isnan(rate) || std::isinf(rate) || rate <= 0.0)
    113         return;
    114 
    115     m_rate = min(AudioResampler::MaxRate, rate);
    116 }
    117 
    118 void AudioResampler::reset()
    119 {
    120     unsigned numberOfChannels = m_kernels.size();
    121     for (unsigned i = 0; i < numberOfChannels; ++i)
    122         m_kernels[i]->reset();
    123 }
    124 
    125 } // namespace WebCore
    126 
    127 #endif // ENABLE(WEB_AUDIO)
    128