| /* |
| * 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. |
| */ |
| |
| #ifndef SincResampler_h |
| #define SincResampler_h |
| |
| #include "platform/PlatformExport.h" |
| #include "platform/audio/AudioArray.h" |
| #include "platform/audio/AudioSourceProvider.h" |
| |
| namespace WebCore { |
| |
| // SincResampler is a high-quality sample-rate converter. |
| |
| class PLATFORM_EXPORT SincResampler { |
| public: |
| // scaleFactor == sourceSampleRate / destinationSampleRate |
| // kernelSize can be adjusted for quality (higher is better) |
| // numberOfKernelOffsets is used for interpolation and is the number of sub-sample kernel shifts. |
| SincResampler(double scaleFactor, unsigned kernelSize = 32, unsigned numberOfKernelOffsets = 32); |
| |
| // Processes numberOfSourceFrames from source to produce numberOfSourceFrames / scaleFactor frames in destination. |
| void process(const float* source, float* destination, unsigned numberOfSourceFrames); |
| |
| // Process with input source callback function for streaming applications. |
| void process(AudioSourceProvider*, float* destination, size_t framesToProcess); |
| |
| protected: |
| void initializeKernel(); |
| void consumeSource(float* buffer, unsigned numberOfSourceFrames); |
| |
| double m_scaleFactor; |
| unsigned m_kernelSize; |
| unsigned m_numberOfKernelOffsets; |
| |
| // 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; |
| |
| // This is the number of destination frames we generate per processing pass on the buffer. |
| unsigned m_blockSize; |
| |
| // Source is copied into this buffer for each processing pass. |
| AudioFloatArray m_inputBuffer; |
| |
| const float* m_source; |
| unsigned m_sourceFramesAvailable; |
| |
| // m_sourceProvider is used to provide the audio input stream to the resampler. |
| AudioSourceProvider* m_sourceProvider; |
| |
| // The buffer is primed once at the very beginning of processing. |
| bool m_isBufferPrimed; |
| }; |
| |
| } // namespace WebCore |
| |
| #endif // SincResampler_h |