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/*
* Copyright (C) 2011 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.
* 3. Neither the name of Apple Computer, Inc. ("Apple") nor the names of
* its contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY APPLE 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 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 "platform/audio/AudioBus.h"
#include "platform/audio/MultiChannelResampler.h"
#include "wtf/PtrUtil.h"
namespace blink {
namespace {
// ChannelProvider provides a single channel of audio data (one channel at a
// time) for each channel of data provided to us in a multi-channel provider.
class ChannelProvider final : public AudioSourceProvider {
public:
ChannelProvider(AudioSourceProvider* multiChannelProvider,
unsigned numberOfChannels)
: m_multiChannelProvider(multiChannelProvider),
m_numberOfChannels(numberOfChannels),
m_currentChannel(0),
m_framesToProcess(0) {}
// provideInput() will be called once for each channel, starting with the
// first channel. Each time it's called, it will provide the next channel of
// data.
void provideInput(AudioBus* bus, size_t framesToProcess) override {
bool isBusGood = bus && bus->numberOfChannels() == 1;
ASSERT(isBusGood);
if (!isBusGood)
return;
// Get the data from the multi-channel provider when the first channel asks
// for it. For subsequent channels, we can just dish out the channel data
// from that (stored in m_multiChannelBus).
if (!m_currentChannel) {
m_framesToProcess = framesToProcess;
m_multiChannelBus = AudioBus::create(m_numberOfChannels, framesToProcess);
m_multiChannelProvider->provideInput(m_multiChannelBus.get(),
framesToProcess);
}
// All channels must ask for the same amount. This should always be the
// case, but let's just make sure.
bool isGood =
m_multiChannelBus.get() && framesToProcess == m_framesToProcess;
ASSERT(isGood);
if (!isGood)
return;
// Copy the channel data from what we received from m_multiChannelProvider.
ASSERT(m_currentChannel <= m_numberOfChannels);
if (m_currentChannel < m_numberOfChannels) {
memcpy(bus->channel(0)->mutableData(),
m_multiChannelBus->channel(m_currentChannel)->data(),
sizeof(float) * framesToProcess);
++m_currentChannel;
}
}
private:
AudioSourceProvider* m_multiChannelProvider;
RefPtr<AudioBus> m_multiChannelBus;
unsigned m_numberOfChannels;
unsigned m_currentChannel;
// Used to verify that all channels ask for the same amount.
size_t m_framesToProcess;
};
} // namespace
MultiChannelResampler::MultiChannelResampler(double scaleFactor,
unsigned numberOfChannels)
: m_numberOfChannels(numberOfChannels) {
// Create each channel's resampler.
for (unsigned channelIndex = 0; channelIndex < numberOfChannels;
++channelIndex)
m_kernels.push_back(WTF::makeUnique<SincResampler>(scaleFactor));
}
void MultiChannelResampler::process(AudioSourceProvider* provider,
AudioBus* destination,
size_t framesToProcess) {
// The provider can provide us with multi-channel audio data. But each of our
// single-channel resamplers (kernels) below requires a provider which
// provides a single unique channel of data. channelProvider wraps the
// original multi-channel provider and dishes out one channel at a time.
ChannelProvider channelProvider(provider, m_numberOfChannels);
for (unsigned channelIndex = 0; channelIndex < m_numberOfChannels;
++channelIndex) {
// Depending on the sample-rate scale factor, and the internal buffering
// used in a SincResampler kernel, this call to process() will only
// sometimes call provideInput() on the channelProvider. However, if it
// calls provideInput() for the first channel, then it will call it for the
// remaining channels, since they all buffer in the same way and are
// processing the same number of frames.
m_kernels[channelIndex]->process(
&channelProvider, destination->channel(channelIndex)->mutableData(),
framesToProcess);
}
}
} // namespace blink
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