Chris@137: /* -*- c-basic-offset: 4 indent-tabs-mode: nil -*-  vi:set ts=8 sts=4 sw=4: */
Chris@150: /*
Chris@150:     QM DSP Library
Chris@150: 
Chris@150:     Centre for Digital Music, Queen Mary, University of London.
Chris@150:     This file by Chris Cannam.
Chris@150: 
Chris@150:     This program is free software; you can redistribute it and/or
Chris@150:     modify it under the terms of the GNU General Public License as
Chris@150:     published by the Free Software Foundation; either version 2 of the
Chris@150:     License, or (at your option) any later version.  See the file
Chris@150:     COPYING included with this distribution for more information.
Chris@150: */
Chris@137: 
Chris@137: #ifndef RESAMPLER_H
Chris@137: #define RESAMPLER_H
Chris@137: 
Chris@137: #include <vector>
Chris@137: 
Chris@150: /**
Chris@150:  * Resampler resamples a stream from one integer sample rate to
Chris@150:  * another (arbitrary) rate, using a kaiser-windowed sinc filter.  The
Chris@150:  * results and performance are pretty similar to libraries such as
Chris@150:  * libsamplerate, though this implementation does not support
Chris@150:  * time-varying ratios (the ratio is fixed on construction).
Chris@150:  *
Chris@150:  * See also Decimator, which is faster and rougher but supports only
Chris@150:  * power-of-two downsampling factors.
Chris@150:  */
Chris@137: class Resampler
Chris@137: {
Chris@137: public:
Chris@137:     /**
Chris@137:      * Construct a Resampler to resample from sourceRate to
Chris@137:      * targetRate.
Chris@137:      */
Chris@137:     Resampler(int sourceRate, int targetRate);
Chris@149: 
Chris@149:     /**
Chris@149:      * Construct a Resampler to resample from sourceRate to
Chris@149:      * targetRate, using the given filter parameters.
Chris@149:      */
Chris@149:     Resampler(int sourceRate, int targetRate,
Chris@149:               double snr, double bandwidth);
Chris@149: 
Chris@137:     virtual ~Resampler();
Chris@137: 
Chris@137:     /**
Chris@137:      * Read n input samples from src and write resampled data to
Chris@137:      * dst. The return value is the number of samples written, which
Chris@137:      * will be no more than ceil((n * targetRate) / sourceRate). The
Chris@137:      * caller must ensure the dst buffer has enough space for the
Chris@137:      * samples returned.
Chris@137:      */
Chris@137:     int process(const double *src, double *dst, int n);
Chris@137: 
Chris@137:     /**
Chris@137:      * Return the number of samples of latency at the output due by
Chris@137:      * the filter. (That is, the output will be delayed by this number
Chris@137:      * of samples relative to the input.)
Chris@137:      */
Chris@137:     int getLatency() const { return m_latency; }
Chris@137: 
Chris@138:     /**
Chris@138:      * Carry out a one-off resample of a single block of n
Chris@138:      * samples. The output is latency-compensated.
Chris@138:      */
Chris@138:     static std::vector<double> resample
Chris@138:     (int sourceRate, int targetRate, const double *data, int n);
Chris@138: 
Chris@137: private:
Chris@137:     int m_sourceRate;
Chris@137:     int m_targetRate;
Chris@137:     int m_gcd;
Chris@137:     int m_filterLength;
Chris@137:     int m_bufferLength;
Chris@137:     int m_latency;
Chris@156:     double m_peakToPole;
Chris@137:     
Chris@137:     struct Phase {
Chris@137:         int nextPhase;
Chris@137:         std::vector<double> filter;
Chris@137:         int drop;
Chris@137:     };
Chris@137: 
Chris@137:     Phase *m_phaseData;
Chris@137:     int m_phase;
Chris@139:     std::vector<double> m_buffer;
Chris@145:     int m_bufferOrigin;
Chris@137: 
Chris@149:     void initialise(double, double);
Chris@141:     double reconstructOne();
Chris@137: };
Chris@137: 
Chris@137: #endif
Chris@137: