| /* |
| * 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/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 |