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