DownBeat Class Reference

#include <DownBeat.h>

Public Member Functions
	DownBeat (float originalSampleRate, size_t decimationFactor, size_t dfIncrement)
	~DownBeat ()
void	setBeatsPerBar (int bpb)
void	findDownBeats (const float *audio, size_t audioLength, const vector< double > &beats, vector< int > &downbeats)
void	getBeatSD (vector< double > &beatsd) const
void	pushAudioBlock (const float *audio)
const float *	getBufferedAudio (size_t &length) const
void	resetAudioBuffer ()

Private Types
typedef vector< int >	i_vec_t
typedef vector< vector< int > >	i_mat_t
typedef vector< double >	d_vec_t
typedef vector< vector< double > >	d_mat_t

Private Member Functions
void	makeDecimators ()
double	measureSpecDiff (d_vec_t oldspec, d_vec_t newspec)

Private Attributes
int	m_bpb
float	m_rate
size_t	m_factor
size_t	m_increment
Decimator *	m_decimator1
Decimator *	m_decimator2
float *	m_buffer
float *	m_decbuf
size_t	m_bufsiz
size_t	m_buffill
size_t	m_beatframesize
double *	m_beatframe
FFTReal *	m_fft
double *	m_fftRealOut
double *	m_fftImagOut
d_vec_t	m_beatsd

Detailed Description

This class takes an input audio signal and a sequence of beat locations (calculated e.g. by TempoTrackV2) and estimates which of the beat locations are downbeats (first beat of the bar).

The input audio signal is expected to have been downsampled to a very low sampling rate (e.g. 2700Hz). A utility function for downsampling and buffering incoming block-by-block audio is provided.

Definition at line 38 of file DownBeat.h.

Member Typedef Documentation

d_mat_t

typedef vector<vector<double> > DownBeat::d_mat_t

private

Definition at line 113 of file DownBeat.h.

d_vec_t

typedef vector<double> DownBeat::d_vec_t

private

Definition at line 112 of file DownBeat.h.

i_mat_t

typedef vector<vector<int> > DownBeat::i_mat_t

private

Definition at line 111 of file DownBeat.h.

i_vec_t

typedef vector<int> DownBeat::i_vec_t

private

Definition at line 110 of file DownBeat.h.

Constructor & Destructor Documentation

DownBeat()

DownBeat::DownBeat	(	float	originalSampleRate,
		size_t	decimationFactor,
		size_t	dfIncrement
	)

Construct a downbeat locator that will operate on audio at the downsampled by the given decimation factor from the given original sample rate, plus beats extracted from the same audio at the given original sample rate with the given frame increment.

decimationFactor must be a power of two no greater than 64, and dfIncrement must be a multiple of decimationFactor.

~DownBeat()

DownBeat::~DownBeat

(

)

Member Function Documentation

findDownBeats()

void DownBeat::findDownBeats	(	const float *	audio,
		size_t	audioLength,
		const vector< double > &	beats,
		vector< int > &	downbeats
	)

Estimate which beats are down-beats.

audio contains the input audio stream after downsampling, and audioLength contains the number of samples in this downsampled stream.

beats contains a series of beat positions expressed in multiples of the df increment at the audio's original sample rate, as described to the constructor.

The returned downbeat array contains a series of indices to the beats array.

getBeatSD()

void DownBeat::getBeatSD

(

vector< double > &

beatsd

)

const

Return the beat spectral difference function. This is calculated during findDownBeats, so this function can only be meaningfully called after that has completed. The returned vector contains one value for each of the beat times passed in to findDownBeats, less one. Each value contains the spectral difference between region prior to the beat's nominal position and the region following it.

getBufferedAudio()

const float* DownBeat::getBufferedAudio

(

size_t &

length

)

const

Retrieve the accumulated audio produced by pushAudioBlock calls.

makeDecimators()

void DownBeat::makeDecimators ( )

private

measureSpecDiff()

double DownBeat::measureSpecDiff ( d_vec_t  oldspec, d_vec_t  newspec  )

private

pushAudioBlock()

void DownBeat::pushAudioBlock

(

const float *

audio

)

For your downsampling convenience: call this function repeatedly with input audio blocks containing dfIncrement samples at the original sample rate, to decimate them to the downsampled rate and buffer them within the DownBeat class.

Call getBufferedAudio() to retrieve the results after all blocks have been processed.

resetAudioBuffer()

void DownBeat::resetAudioBuffer

(

)

Clear any buffered downsampled audio data.

setBeatsPerBar()

void DownBeat::setBeatsPerBar

(

int

bpb

)

Member Data Documentation

m_beatframe

double* DownBeat::m_beatframe

private

Definition at line 129 of file DownBeat.h.

m_beatframesize

size_t DownBeat::m_beatframesize

private

Definition at line 128 of file DownBeat.h.

m_beatsd

d_vec_t DownBeat::m_beatsd

private

Definition at line 133 of file DownBeat.h.

m_bpb

int DownBeat::m_bpb

private

Definition at line 118 of file DownBeat.h.

m_buffer

float* DownBeat::m_buffer

private

Definition at line 124 of file DownBeat.h.

m_buffill

size_t DownBeat::m_buffill

private

Definition at line 127 of file DownBeat.h.

m_bufsiz

size_t DownBeat::m_bufsiz

private

Definition at line 126 of file DownBeat.h.

m_decbuf

float* DownBeat::m_decbuf

private

Definition at line 125 of file DownBeat.h.

m_decimator1

Decimator* DownBeat::m_decimator1

private

Definition at line 122 of file DownBeat.h.

m_decimator2

Decimator* DownBeat::m_decimator2

private

Definition at line 123 of file DownBeat.h.

m_factor

size_t DownBeat::m_factor

private

Definition at line 120 of file DownBeat.h.

m_fft

FFTReal* DownBeat::m_fft

private

Definition at line 130 of file DownBeat.h.

m_fftImagOut

double* DownBeat::m_fftImagOut

private

Definition at line 132 of file DownBeat.h.

m_fftRealOut

double* DownBeat::m_fftRealOut

private

Definition at line 131 of file DownBeat.h.

m_increment

size_t DownBeat::m_increment

private

Definition at line 121 of file DownBeat.h.

m_rate

float DownBeat::m_rate

private

Definition at line 119 of file DownBeat.h.

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The documentation for this class was generated from the following file:

• DownBeat.h