Chris@366: /* -*- c-basic-offset: 4 indent-tabs-mode: nil -*-  vi:set ts=8 sts=4 sw=4: */
Chris@366: /*
Chris@366:     Constant-Q library
Chris@366:     Copyright (c) 2013-2014 Queen Mary, University of London
Chris@366: 
Chris@366:     Permission is hereby granted, free of charge, to any person
Chris@366:     obtaining a copy of this software and associated documentation
Chris@366:     files (the "Software"), to deal in the Software without
Chris@366:     restriction, including without limitation the rights to use, copy,
Chris@366:     modify, merge, publish, distribute, sublicense, and/or sell copies
Chris@366:     of the Software, and to permit persons to whom the Software is
Chris@366:     furnished to do so, subject to the following conditions:
Chris@366: 
Chris@366:     The above copyright notice and this permission notice shall be
Chris@366:     included in all copies or substantial portions of the Software.
Chris@366: 
Chris@366:     THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
Chris@366:     EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
Chris@366:     MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
Chris@366:     NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
Chris@366:     CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF
Chris@366:     CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
Chris@366:     WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
Chris@366: 
Chris@366:     Except as contained in this notice, the names of the Centre for
Chris@366:     Digital Music; Queen Mary, University of London; and Chris Cannam
Chris@366:     shall not be used in advertising or otherwise to promote the sale,
Chris@366:     use or other dealings in this Software without prior written
Chris@366:     authorization.
Chris@366: */
Chris@366: 
Chris@366: #ifndef RESAMPLER_H
Chris@366: #define RESAMPLER_H
Chris@366: 
Chris@366: #include <vector>
Chris@366: 
Chris@366: /**
Chris@366:  * Resampler resamples a stream from one integer sample rate to
Chris@366:  * another (arbitrary) rate, using a kaiser-windowed sinc filter.  The
Chris@366:  * results and performance are pretty similar to libraries such as
Chris@366:  * libsamplerate, though this implementation does not support
Chris@366:  * time-varying ratios (the ratio is fixed on construction).
Chris@366:  *
Chris@366:  * See also Decimator, which is faster and rougher but supports only
Chris@366:  * power-of-two downsampling factors.
Chris@366:  */
Chris@366: class Resampler
Chris@366: {
Chris@366: public:
Chris@366:     /**
Chris@366:      * Construct a Resampler to resample from sourceRate to
Chris@366:      * targetRate.
Chris@366:      */
Chris@366:     Resampler(int sourceRate, int targetRate);
Chris@366: 
Chris@366:     /**
Chris@366:      * Construct a Resampler to resample from sourceRate to
Chris@366:      * targetRate, using the given filter parameters.
Chris@366:      */
Chris@366:     Resampler(int sourceRate, int targetRate,
Chris@366:               double snr, double bandwidth);
Chris@366: 
Chris@366:     virtual ~Resampler();
Chris@366: 
Chris@366:     /**
Chris@366:      * Read n input samples from src and write resampled data to
Chris@366:      * dst. The return value is the number of samples written, which
Chris@366:      * will be no more than ceil((n * targetRate) / sourceRate). The
Chris@366:      * caller must ensure the dst buffer has enough space for the
Chris@366:      * samples returned.
Chris@366:      */
Chris@366:     int process(const double *src, double *dst, int n);
Chris@366: 
Chris@366:     /**
Chris@366:      * Read n input samples from src and return resampled data by
Chris@366:      * value.
Chris@366:      */
Chris@366:     std::vector<double> process(const double *src, int n);
Chris@366: 
Chris@366:     /**
Chris@366:      * Return the number of samples of latency at the output due by
Chris@366:      * the filter. (That is, the output will be delayed by this number
Chris@366:      * of samples relative to the input.)
Chris@366:      */
Chris@366:     int getLatency() const { return m_latency; }
Chris@366: 
Chris@366:     /**
Chris@366:      * Carry out a one-off resample of a single block of n
Chris@366:      * samples. The output is latency-compensated.
Chris@366:      */
Chris@366:     static std::vector<double> resample
Chris@366:     (int sourceRate, int targetRate, const double *data, int n);
Chris@366: 
Chris@366: private:
Chris@366:     int m_sourceRate;
Chris@366:     int m_targetRate;
Chris@366:     int m_gcd;
Chris@366:     int m_filterLength;
Chris@366:     int m_latency;
Chris@366:     double m_peakToPole;
Chris@366:     
Chris@366:     struct Phase {
Chris@366:         int nextPhase;
Chris@366:         std::vector<double> filter;
Chris@366:         int drop;
Chris@366:     };
Chris@366: 
Chris@366:     Phase *m_phaseData;
Chris@366:     int m_phase;
Chris@366:     std::vector<double> m_buffer;
Chris@366:     int m_bufferOrigin;
Chris@366: 
Chris@366:     void initialise(double, double);
Chris@366:     double reconstructOne();
Chris@366: };
Chris@366: 
Chris@366: #endif
Chris@366: