Chris@27: /* -*- c-basic-offset: 4 indent-tabs-mode: nil -*-  vi:set ts=8 sts=4 sw=4: */
Chris@27: 
Chris@27: /*
Chris@27:     Sonic Visualiser
Chris@27:     An audio file viewer and annotation editor.
Chris@27:     Centre for Digital Music, Queen Mary, University of London.
Chris@27:     This file copyright 2006 Chris Cannam.
Chris@27:     
Chris@27:     This program is free software; you can redistribute it and/or
Chris@27:     modify it under the terms of the GNU General Public License as
Chris@27:     published by the Free Software Foundation; either version 2 of the
Chris@27:     License, or (at your option) any later version.  See the file
Chris@27:     COPYING included with this distribution for more information.
Chris@27: */
Chris@27: 
Chris@27: #ifndef _INTEGER_TIME_STRETCHER_H_
Chris@27: #define _INTEGER_TIME_STRETCHER_H_
Chris@27: 
Chris@27: #include "base/Window.h"
Chris@27: #include "base/RingBuffer.h"
Chris@27: 
Chris@27: #include <fftw3.h>
Chris@27: 
Chris@27: /**
Chris@27:  * A time stretcher that slows down audio by an integer multiple of
Chris@27:  * its original duration, preserving pitch.  This uses the simple
Chris@27:  * phase vocoder technique from DAFX pp275-276, adding a block-based
Chris@27:  * stream oriented API.
Chris@27:  *
Chris@27:  * Causes significant transient smearing, but sounds good for steady
Chris@27:  * notes and is generally predictable.
Chris@27:  */
Chris@27: 
Chris@27: class IntegerTimeStretcher
Chris@27: {
Chris@27: public:
Chris@27:     IntegerTimeStretcher(size_t ratio,
Chris@27: 			 size_t maxProcessInputBlockSize,
Chris@27: 			 size_t inputIncrement = 64,
Chris@27: 			 size_t windowSize = 2048,
Chris@27: 			 WindowType windowType = HanningWindow);
Chris@27:     virtual ~IntegerTimeStretcher();
Chris@27: 
Chris@27:     void process(double *input, double *output, size_t samples);
Chris@27: 
Chris@27:     /**
Chris@27:      * Get the hop size for input.  Smaller values may produce better
Chris@27:      * results, at a cost in processing time.  Larger values are
Chris@27:      * faster but increase the likelihood of echo-like effects.  The
Chris@27:      * default is 64, which is usually pretty good, though heavy on
Chris@27:      * processor power.
Chris@27:      */
Chris@27:     size_t getInputIncrement() const { return m_n1; }
Chris@27: 
Chris@27:     /**
Chris@27:      * Get the window size for FFT processing.  Must be larger than
Chris@27:      * the input and output increments.  The default is 2048.
Chris@27:      */
Chris@27:     size_t getWindowSize() const { return m_wlen; }
Chris@27: 
Chris@27:     /**
Chris@27:      * Get the window type.  The default is a Hanning window.
Chris@27:      */
Chris@27:     WindowType getWindowType() const { return m_window->getType(); }
Chris@27: 
Chris@27:     size_t getRatio() const { return m_ratio; }
Chris@27:     size_t getOutputIncrement() const { return getInputIncrement() * getRatio(); }
Chris@27:     size_t getProcessingLatency() const;
Chris@27: 
Chris@27: protected:
Chris@27:     void processBlock(double *in, double *out);
Chris@27: 
Chris@27:     size_t m_ratio;
Chris@27:     size_t m_n1;
Chris@27:     size_t m_n2;
Chris@27:     size_t m_wlen;
Chris@27:     Window<double> *m_window;
Chris@27: 
Chris@27:     fftw_complex *m_time;
Chris@27:     fftw_complex *m_freq;
Chris@27:     double *m_dbuf;
Chris@27: 
Chris@27:     fftw_plan m_plan;
Chris@27:     fftw_plan m_iplan;
Chris@27:     
Chris@27:     RingBuffer<double> m_inbuf;
Chris@27:     RingBuffer<double> m_outbuf;
Chris@27:     double *m_mashbuf;
Chris@27: };
Chris@27: 
Chris@27: #endif