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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 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 "config.h"
#if ENABLE(WEB_AUDIO)
#include "MultiChannelResampler.h"
#include "AudioBus.h"
#include "SincResampler.h"
#include <functional>
#include <wtf/Algorithms.h>
namespace WebCore {
MultiChannelResampler::MultiChannelResampler(double scaleFactor, unsigned numberOfChannels, unsigned requestFrames, Function<void(AudioBus*, size_t framesToProcess)>&& provideInput)
: m_numberOfChannels(numberOfChannels)
, m_provideInput(WTFMove(provideInput))
, m_multiChannelBus(AudioBus::create(numberOfChannels, requestFrames, false))
{
// As an optimization, we will use the buffer passed to provideInputForChannel() as channel memory for the first channel so we
// only need to allocate memory if there is more than one channel.
if (numberOfChannels > 1) {
m_channelsMemory = Vector<std::unique_ptr<AudioFloatArray>>(numberOfChannels - 1, [&](size_t i) {
size_t channelIndex = i + 1;
auto floatArray = makeUnique<AudioFloatArray>(requestFrames);
m_multiChannelBus->setChannelMemory(channelIndex, floatArray->data(), requestFrames);
return floatArray;
});
}
// Create each channel's resampler.
m_kernels = Vector<std::unique_ptr<SincResampler>>(numberOfChannels, [&](size_t channelIndex) {
return makeUnique<SincResampler>(scaleFactor, requestFrames, std::bind(&MultiChannelResampler::provideInputForChannel, this, std::placeholders::_1, std::placeholders::_2, channelIndex));
});
}
MultiChannelResampler::~MultiChannelResampler() = default;
void MultiChannelResampler::process(AudioBus* destination, size_t framesToProcess)
{
ASSERT(m_numberOfChannels == destination->numberOfChannels());
if (destination->numberOfChannels() == 1) {
// Fast path when the bus is mono to avoid the chunking below.
m_kernels[0]->process(destination->channel(0)->mutableSpan(), framesToProcess);
return;
}
// We need to ensure that SincResampler only calls provideInputForChannel() once for each channel or it will confuse the logic
// inside provideInputForChannel(). To ensure this, we chunk the number of requested frames into SincResampler::chunkSize()
// sized chunks. SincResampler guarantees it will only call provideInputForChannel() once once we resample this way.
m_outputFramesReady = 0;
while (m_outputFramesReady < framesToProcess) {
size_t chunkSize = m_kernels[0]->chunkSize();
size_t framesThisTime = std::min(framesToProcess - m_outputFramesReady, chunkSize);
for (unsigned channelIndex = 0; channelIndex < m_numberOfChannels; ++channelIndex) {
ASSERT(chunkSize == m_kernels[channelIndex]->chunkSize());
auto* channel = destination->channel(channelIndex);
m_kernels[channelIndex]->process(channel->mutableSpan().subspan(m_outputFramesReady), framesThisTime);
}
m_outputFramesReady += framesThisTime;
}
}
void MultiChannelResampler::provideInputForChannel(std::span<float> buffer, size_t framesToProcess, unsigned channelIndex)
{
ASSERT(channelIndex < m_multiChannelBus->numberOfChannels());
ASSERT(framesToProcess == m_multiChannelBus->length());
if (!channelIndex) {
// As an optimization, we use the provided buffer as memory for the first channel in the AudioBus. This avoids
// having to memcpy() for the first channel.
RELEASE_ASSERT(framesToProcess <= buffer.size());
m_multiChannelBus->setChannelMemory(0, buffer.data(), framesToProcess);
m_provideInput(m_multiChannelBus.get(), framesToProcess);
return;
}
// Copy the channel data from what we received from m_multiChannelProvider.
memcpySpan(buffer.subspan(0, framesToProcess), m_multiChannelBus->channel(channelIndex)->span().subspan(0, framesToProcess));
}
} // namespace WebCore
#endif // ENABLE(WEB_AUDIO)
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