cannam@54: /* -*- c-basic-offset: 4 indent-tabs-mode: nil -*-  vi:set ts=8 sts=4 sw=4: */
cannam@54: 
cannam@54: /*
cannam@54:     QM DSP Library
cannam@54: 
cannam@54:     Centre for Digital Music, Queen Mary, University of London.
cannam@54:     This file copyright 2008-2009 Matthew Davies and QMUL.
cannam@54:     All rights reserved.
cannam@54: */
cannam@54: 
cannam@54: #ifndef DOWNBEAT_H
cannam@54: #define DOWNBEAT_H
cannam@54: 
cannam@54: #include <vector>
cannam@54: 
cannam@54: #include "dsp/rateconversion/Decimator.h"
cannam@54: 
cannam@54: using std::vector;
cannam@54: 
cannam@54: /**
cannam@54:  * This class takes an input audio signal and a sequence of beat
cannam@54:  * locations (calculated e.g. by TempoTrackV2) and estimates which of
cannam@54:  * the beat locations are downbeats (first beat of the bar).
cannam@54:  * 
cannam@54:  * The input audio signal is expected to have been downsampled to a
cannam@54:  * very low sampling rate (e.g. 2700Hz).  A utility function for
cannam@54:  * downsampling and buffering incoming block-by-block audio is
cannam@54:  * provided.
cannam@54:  */
cannam@54: class DownBeat
cannam@54: {
cannam@54: public:
cannam@54:     /**
cannam@54:      * Construct a downbeat locator that will operate on audio at the
cannam@54:      * downsampled by the given decimation factor from the given
cannam@54:      * original sample rate, plus beats extracted from the same audio
cannam@54:      * at the given original sample rate with the given frame
cannam@54:      * increment.
cannam@54:      *
cannam@54:      * decimationFactor must be a power of two no greater than 64, and
cannam@54:      * dfIncrement must be a multiple of decimationFactor.
cannam@54:      */
cannam@54:     DownBeat(float originalSampleRate,
cannam@54:              size_t decimationFactor,
cannam@54:              size_t dfIncrement);
cannam@54:     ~DownBeat();
cannam@54: 
cannam@54:     /**
cannam@54:      * Estimate which beats are down-beats.
cannam@54:      * 
cannam@54:      * audio contains the input audio stream after downsampling, and
cannam@54:      * audioLength contains the number of samples in this downsampled
cannam@54:      * stream.
cannam@54:      *
cannam@54:      * beats contains a series of beat positions expressed in
cannam@54:      * multiples of the df increment at the audio's original sample
cannam@54:      * rate, as described to the constructor.
cannam@54:      *
cannam@54:      * The returned downbeat array contains a series of indices to the
cannam@54:      * beats array.
cannam@54:      */
cannam@54:     void findDownBeats(const double *audio, // downsampled
cannam@54:                        size_t audioLength, // after downsampling
cannam@54:                        const vector<double> &beats,
cannam@54:                        vector<int> &downbeats);
cannam@54:     
cannam@54:     /**
cannam@54:      * For your downsampling convenience: call this function
cannam@54:      * repeatedly with input audio blocks containing dfIncrement
cannam@54:      * samples at the original sample rate, to decimate them to the
cannam@54:      * downsampled rate and buffer them within the DownBeat class.
cannam@54:      *     
cannam@54:      * Call getBufferedAudio() to retrieve the results after all
cannam@54:      * blocks have been processed.
cannam@54:      */
cannam@54:     void pushAudioBlock(const double *audio);
cannam@54:     
cannam@54:     /**
cannam@54:      * Retrieve the accumulated audio produced by pushAudioBlock calls.
cannam@54:      */
cannam@54:     const double *getBufferedAudio(size_t &length) const;
cannam@54: 
cannam@54: private:
cannam@54:     typedef vector<int> i_vec_t;
cannam@54:     typedef vector<vector<int> > i_mat_t;
cannam@54:     typedef vector<double> d_vec_t;
cannam@54:     typedef vector<vector<double> > d_mat_t;
cannam@54: 
cannam@54:     void makeDecimators();
cannam@54:     double measureSpecDiff(d_vec_t oldspec, d_vec_t newspec);
cannam@54: 
cannam@54:     float m_rate;
cannam@54:     size_t m_factor;
cannam@54:     size_t m_increment;
cannam@54:     Decimator *m_decimator1;
cannam@54:     Decimator *m_decimator2;
cannam@54:     double *m_buffer;
cannam@54:     double *m_decbuf;
cannam@54:     size_t m_bufsiz;
cannam@54:     size_t m_buffill;
cannam@54:     size_t m_beatframesize;
cannam@54:     double *m_beatframe;
cannam@54:     double *m_fftRealOut;
cannam@54:     double *m_fftImagOut;
cannam@54: };
cannam@54: 
cannam@54: #endif