TQuickSpectrogram Class Reference

#include <quickspec.h>

Collaboration diagram for TQuickSpectrogram:

Public Member Functions
__fastcall	TQuickSpectrogram (void *AParent, int AnId, bool Ausex, bool Auseph, GetBuf G)
QSPEC_FORMAT *__fastcall	A (int fr)
	accesses amplitude spectrogram at frame fr More...
void	FreeBuffers ()
	discards all computed frames and free memory More...
int	Invalidate (int From, int To)
	discards computed frames More...
QSPEC_FORMAT *__fastcall	Ph (int fr)
	accesses phase spectrogram at frame fr More...
void	SetFrCapacity (int AnFrCapacity)
cmplx< QSPEC_FORMAT > *__fastcall	Spec (int fr)
	accesses complex spectrogram at frame fr More...

Data Fields
int	Id
	an identifier given at create time, used as argument for calling GetFFTBuffers()
void *	Parent
	a pointer used as argument for calling GetFFTBuffers()
GetBuf	GetFFTBuffers
	if specified, this supplies FFT buffers
int	Capacity
	size of $Frame[] and &Valid[], usually set to the total number of frames of the data
int *	Frame
	indices to individual frames in internal storage
int *	Valid
	validity tags to individual frames in internal storage
WindowType	WinType
	window type for computing spectrogram
double	WinParam
	additional parameter specifying certain window types (Gaussian, Kaiser, etc.)
void *	Data
	pointer to waveform audio
int	DataLength
	length of waveform audio, in samples
int	BytesPerSample
	bytes per sample of waveform audio
int	Offst
	frame offset
int	Wid
	frame size, the same as window size

Detailed Description

TQuickSpectrogram is a spectrogram class the handles the computation and storage of a spectrogram.

Using TQuickSpectrogram:

TQuickSpectrogram provides read-only access to the spectrogram of a given waveform. The spectrogram contains a sequence of windowed Fourier transforms, computed from uniformly placed frames. The 0th frame starts at 0 (inclusive) and finishes at Wid (exclusive). Each spectrum has Wid/2+1 entries.

Follow these steps:

1. create a QuickSpectrogram, specifying usex and useph, and optionally, external buffer provide G and its arguments Id and Parent;
2. set Data, DataLength and BytesPerSample;
3. set frame size and hop size Wid and Offst;
4. if G is not specified, set window type (optional extra parameter) for computing spectra;
5. access the spectrogram via A(fr), Spec(fr) (optional) and Ph(fr) (optional). Steps 2~4 do not have to follow the given order.

Call Invalidate() to notify the object of changes of waveform content. Call FreeBuffers() to return the object to the initial state before step 2.

Constructor & Destructor Documentation

__fastcall TQuickSpectrogram::TQuickSpectrogram	(	void *	AParent,
		int	AnId,
		bool	Ausex,
		bool	Auseph,
		GetBuf	G
	)

method TQuickSpectrogram::TQuickSpectrogram:

In: AParent: pointer argument for calling G, if G is specified AnId: integer argument for calling G, if G is specified G: pointer to a function that supplies buffers used for FFT, 0 by default Ausex: set if complete complex spectrogram is to be buffered and accessible Auseph: set if phase spectrogram is to be buffered and accessible

Member Function Documentation

QSPEC_FORMAT *__fastcall TQuickSpectrogram::A

(

int

fr

)

accesses amplitude spectrogram at frame fr

method TQuickSpectrogram::A: accesses amplitude spectrogram by frame

In: fr: frame index, 0-based

Returns pointer to amplitude spectrum of the fr'th frame, NULL if N/A

void TQuickSpectrogram::FreeBuffers

(

)

discards all computed frames and free memory

method TQuickSpectrogram::FreeBuffers: discards all computed spectra and free all internal buffers. This returns the TQuickSpectrogram to its initial state before any frame is accessed. After calling FreeBuffers() all frames will be recomputed when they are accessed.

int TQuickSpectrogram::Invalidate	(	int	From,
		int	To
	)

discards computed frames

method TQuickSpectrogram::Invalidate: renders all frames that have overlap with interval [From, To], measured in samples, as invalid. Invalid frames are recomputed when they are accessed again.

In: [From, To]: an interval spectrogram over which needs to be updated.

Returns the number of allocated frames affected, no matter if they were valid.

QSPEC_FORMAT *__fastcall TQuickSpectrogram::Ph

(

int

fr

)

accesses phase spectrogram at frame fr

method TQuickSpectrogram::Ph: accesses phase spectrogram by frame

In: fr: frame index, 0-based

Returns pointer to phase spectrum of the fr'th frame, NULL if N/A

void TQuickSpectrogram::SetFrCapacity

(

int

AnFrCapacity

)

method TQuickSpectrogram::SetFrCapacity: sets the capacity, i.e. the maximal number of frames handled by this TQuickSpectrogram.

In: AnFrCapacity: the new Capacity, in frames

This method should not be called to set Capacity to a smaller value.

cmplx< QSPEC_FORMAT > *__fastcall TQuickSpectrogram::Spec

(

int

fr

)

accesses complex spectrogram at frame fr

method TQuickSpectrogram::Ph: accesses complex spectrogram by frame

In: fr: frame index, 0-based

Returns pointer to complex spectrum of the fr'th frame, NULL if N/A

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

• quickspec.h
• quickspec.cpp