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29 #ifndef SincResampler_h
30 #define SincResampler_h
32 #include "platform/PlatformExport.h"
33 #include "platform/audio/AudioArray.h"
34 #include "platform/audio/AudioSourceProvider.h"
38 // SincResampler is a high-quality sample-rate converter.
40 class PLATFORM_EXPORT SincResampler {
42 // scaleFactor == sourceSampleRate / destinationSampleRate
43 // kernelSize can be adjusted for quality (higher is better)
44 // numberOfKernelOffsets is used for interpolation and is the number of sub-sample kernel shifts.
45 SincResampler(double scaleFactor, unsigned kernelSize = 32, unsigned numberOfKernelOffsets = 32);
47 // Processes numberOfSourceFrames from source to produce numberOfSourceFrames / scaleFactor frames in destination.
48 void process(const float* source, float* destination, unsigned numberOfSourceFrames);
50 // Process with input source callback function for streaming applications.
51 void process(AudioSourceProvider*, float* destination, size_t framesToProcess);
54 void initializeKernel();
55 void consumeSource(float* buffer, unsigned numberOfSourceFrames);
58 unsigned m_kernelSize;
59 unsigned m_numberOfKernelOffsets;
61 // m_kernelStorage has m_numberOfKernelOffsets kernels back-to-back, each of size m_kernelSize.
62 // The kernel offsets are sub-sample shifts of a windowed sinc() shifted from 0.0 to 1.0 sample.
63 AudioFloatArray m_kernelStorage;
65 // m_virtualSourceIndex is an index on the source input buffer with sub-sample precision.
66 // It must be double precision to avoid drift.
67 double m_virtualSourceIndex;
69 // This is the number of destination frames we generate per processing pass on the buffer.
72 // Source is copied into this buffer for each processing pass.
73 AudioFloatArray m_inputBuffer;
75 const float* m_source;
76 unsigned m_sourceFramesAvailable;
78 // m_sourceProvider is used to provide the audio input stream to the resampler.
79 AudioSourceProvider* m_sourceProvider;
81 // The buffer is primed once at the very beginning of processing.
82 bool m_isBufferPrimed;
87 #endif // SincResampler_h