87 lines
3.3 KiB
C++
87 lines
3.3 KiB
C++
/**********************************************************************
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Audacity: A Digital Audio Editor
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Audacity(R) is copyright (c) 1999-2012 Audacity Team.
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License: GPL v2. See License.txt.
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Resample.cpp
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Dominic Mazzoni, Rob Sykes, Vaughan Johnson
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**********************************************************************/
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#ifndef __AUDACITY_RESAMPLE_H__
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#define __AUDACITY_RESAMPLE_H__
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#include "SampleFormat.h"
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template< typename Enum > class EnumSetting;
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struct soxr;
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extern "C" void soxr_delete(soxr*);
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struct soxr_deleter {
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void operator () (soxr *p) const { if (p) soxr_delete(p); }
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};
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using soxrHandle = std::unique_ptr<soxr, soxr_deleter>;
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class AUDACITY_DLL_API Resample final
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{
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public:
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/// Resamplers may have more than one method, offering a
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/// tradeoff between speed and quality.
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/// Audacity identifies two methods out of all of the choices:
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/// a Fast method intended for real-time audio I/O, and a Best
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/// method intended for mixing and exporting.
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//
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/// The first parameter lets you select either the best method or
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/// the fast method.
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// dMinFactor and dMaxFactor specify the range of factors for variable-rate resampling.
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// For constant-rate, pass the same value for both.
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Resample(const bool useBestMethod, const double dMinFactor, const double dMaxFactor);
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~Resample();
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static EnumSetting< int > FastMethodSetting;
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static EnumSetting< int > BestMethodSetting;
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/** @brief Main processing function. Resamples from the input buffer to the
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* output buffer.
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*
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* Reads samples from the input buffer, and writes samples to the output
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* buffer. Stops when either is exhausted, or we reach a convenient block
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* end, unless lastFlag is set to force emptying the input buffer.
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* The number of input samples used is returned in inBufferUsed, and the
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* number of output samples generated is the return value of the function.
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* This function may do nothing if you don't pass a large enough output
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* buffer (i.e. there is no where to put a full block of output data)
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@param factor The scaling factor to resample by.
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@param inBuffer Buffer of input samples to be processed (mono)
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@param inBufferLen Length of the input buffer, in samples.
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@param lastFlag Flag to indicate this is the last lot of input samples and
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the buffer needs to be emptied out into the rate converter.
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(unless lastFlag is true, we don't guarantee to process all the samples in
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the input this time, we may leave some for next time)
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@param outBuffer Buffer to write output (converted) samples to.
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@param outBufferLen How big outBuffer is.
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@return Number of input samples consumed, and number of output samples
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created by this call
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*/
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std::pair<size_t, size_t>
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Process(double factor,
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float *inBuffer,
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size_t inBufferLen,
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bool lastFlag,
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float *outBuffer,
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size_t outBufferLen);
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protected:
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void SetMethod(const bool useBestMethod);
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protected:
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int mMethod; // resampler-specific enum for resampling method
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soxrHandle mHandle; // constant-rate or variable-rate resampler (XOR per instance)
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bool mbWantConstRateResampling;
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};
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#endif // __AUDACITY_RESAMPLE_H__
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