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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 "third_party/blink/renderer/platform/audio/multi_channel_resampler.h"
#include <memory>
#include "third_party/blink/renderer/platform/audio/audio_bus.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* multi_channel_provider,
unsigned number_of_channels)
: multi_channel_provider_(multi_channel_provider),
number_of_channels_(number_of_channels),
current_channel_(0),
frames_to_process_(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 frames_to_process) override {
bool is_bus_good = bus && bus->NumberOfChannels() == 1;
DCHECK(is_bus_good);
if (!is_bus_good)
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 (!current_channel_) {
frames_to_process_ = frames_to_process;
multi_channel_bus_ =
AudioBus::Create(number_of_channels_, frames_to_process);
multi_channel_provider_->ProvideInput(multi_channel_bus_.get(),
frames_to_process);
}
// All channels must ask for the same amount. This should always be the
// case, but let's just make sure.
bool is_good =
multi_channel_bus_.get() && frames_to_process == frames_to_process_;
DCHECK(is_good);
if (!is_good)
return;
// Copy the channel data from what we received from m_multiChannelProvider.
DCHECK_LE(current_channel_, number_of_channels_);
if (current_channel_ < number_of_channels_) {
memcpy(bus->Channel(0)->MutableData(),
multi_channel_bus_->Channel(current_channel_)->Data(),
sizeof(float) * frames_to_process);
++current_channel_;
}
}
private:
AudioSourceProvider* multi_channel_provider_;
scoped_refptr<AudioBus> multi_channel_bus_;
unsigned number_of_channels_;
unsigned current_channel_;
// Used to verify that all channels ask for the same amount.
size_t frames_to_process_;
};
} // namespace
MultiChannelResampler::MultiChannelResampler(double scale_factor,
unsigned number_of_channels)
: number_of_channels_(number_of_channels) {
// Create each channel's resampler.
for (unsigned channel_index = 0; channel_index < number_of_channels;
++channel_index)
kernels_.push_back(std::make_unique<SincResampler>(scale_factor));
}
void MultiChannelResampler::Process(AudioSourceProvider* provider,
AudioBus* destination,
size_t frames_to_process) {
// 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 channel_provider(provider, number_of_channels_);
for (unsigned channel_index = 0; channel_index < number_of_channels_;
++channel_index) {
// 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.
kernels_[channel_index]->Process(
&channel_provider, destination->Channel(channel_index)->MutableData(),
frames_to_process);
}
}
} // namespace blink
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