/* * 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 <wtf/Function.h> #include <wtf/Optional.h> #include <wtf/RefPtr.h> namespace WebCore { // SincResampler is a high-quality sample-rate converter. class SincResampler final { WTF_MAKE_FAST_ALLOCATED; 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(float* buffer, size_t framesToProcess)>&& provideInput); size_t chunkSize() const { return m_chunkSize; } // Processes numberOfSourceFrames from source to produce numberOfSourceFrames / scaleFactor frames in destination. static void processBuffer(const float* source, float* destination, unsigned numberOfSourceFrames, double scaleFactor); // Process with provideInput callback function for streaming applications. void process(float* destination, size_t framesToProcess); protected: void initializeKernel(); void updateRegions(bool isSecondLoad); float convolve(const float* inputP, const float* k1, 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(float* buffer, size_t framesToProcess)> m_provideInput; // The number of source frames processed per pass. unsigned m_blockSize { 0 }; size_t m_chunkSize { 0 }; // Source is copied into this buffer for each processing pass. AudioFloatArray m_inputBuffer; // Pointers to the various regions inside |m_inputBuffer|. See the diagram at // the top of the .cpp file for more information. float* m_r0 { nullptr }; float* const m_r1 { nullptr }; float* const m_r2 { nullptr }; float* m_r3 { nullptr }; float* m_r4 { nullptr }; // The buffer is primed once at the very beginning of processing. bool m_isBufferPrimed { false }; }; } // namespace WebCore #endif // SincResampler_h