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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.
*/
#ifndef SincResampler_h
#define SincResampler_h
#include "AudioArray.h"
#include "AudioSourceProvider.h"
#include <span>
#include <wtf/Function.h>
#include <wtf/RefPtr.h>
#include <wtf/TZoneMalloc.h>
namespace WebCore {
// SincResampler is a high-quality sample-rate converter.
class SincResampler final {
WTF_MAKE_TZONE_ALLOCATED(SincResampler);
public:
// scaleFactor == sourceSampleRate / destinationSampleRate
// requestFrames controls the size in frames of the buffer requested by each provideInput() call.
SincResampler(double scaleFactor, unsigned requestFrames, Function<void(std::span<float> buffer, size_t framesToProcess)>&& provideInput);
size_t chunkSize() const { return m_chunkSize; }
// Processes samples in `source` to produce source.size() / scaleFactor frames in `destination`.
WEBCORE_EXPORT static void processBuffer(std::span<const float> source, std::span<float> destination, double scaleFactor);
// Process with provideInput callback function for streaming applications.
void process(std::span<float> destination, size_t framesToProcess);
private:
void initializeKernel();
void updateRegions(bool isSecondLoad);
float convolve(std::span<const float> inputP, std::span<const float> k1, std::span<const float> k2, float kernelInterpolationFactor);
double m_scaleFactor;
// m_kernelStorage has m_numberOfKernelOffsets kernels back-to-back, each of size m_kernelSize.
// The kernel offsets are sub-sample shifts of a windowed sinc() shifted from 0.0 to 1.0 sample.
AudioFloatArray m_kernelStorage;
// m_virtualSourceIndex is an index on the source input buffer with sub-sample precision.
// It must be double precision to avoid drift.
double m_virtualSourceIndex { 0 };
// This is the number of destination frames we generate per processing pass on the buffer.
unsigned m_requestFrames;
Function<void(std::span<float> buffer, size_t framesToProcess)> m_provideInput;
// The number of source frames processed per pass.
size_t m_blockSize { 0 };
size_t m_chunkSize { 0 };
// Source is copied into this buffer for each processing pass.
AudioFloatArray m_inputBuffer;
// Spans to the various regions inside |m_inputBuffer|. See the diagram at
// the top of the .cpp file for more information.
std::span<float> m_r0;
const std::span<float> m_r1;
const std::span<float> m_r2;
std::span<float> m_r3;
std::span<float> m_r4;
// The buffer is primed once at the very beginning of processing.
bool m_isBufferPrimed { false };
};
} // namespace WebCore
#endif // SincResampler_h
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