r8b::CDSPHBDownsampler Class Reference

Half-band downsampler class. More...

#include <CDSPHBDownsampler.h>

Inheritance diagram for r8b::CDSPHBDownsampler:

Collaboration diagram for r8b::CDSPHBDownsampler:

Public Member Functions
	CDSPHBDownsampler (const double ReqAtten, const int SteepIndex, const bool IsThird, const double PrevLatency)
	Constructor initalizes the half-band downsampler. More...
virtual int	getLatency () const
virtual double	getLatencyFrac () const
virtual int	getMaxOutLen (const int MaxInLen) const
virtual void	clear ()
	Function clears (resets) the state of *this object and returns it to the state after construction. More...
virtual int	process (double *ip, int l, double *&op0)
	Function performs DSP processing. More...

Detailed Description

Half-band downsampler class.

Class implements brute-force half-band 2X downsampling that uses small sparse symmetric FIR filters. The output has 2.0 gain.

Constructor & Destructor Documentation

CDSPHBDownsampler()

r8b::CDSPHBDownsampler::CDSPHBDownsampler ( const double  ReqAtten, const int  SteepIndex, const bool  IsThird, const double  PrevLatency  )

inline

Constructor initalizes the half-band downsampler.

Parameters

ReqAtten	Required half-band filter attentuation.
SteepIndex	Steepness index - 0=steepest. Corresponds to general downsampling ratio, e.g. at 4x downsampling 0 is used, at 8x downsampling 1 is used, etc.
IsThird	"True" if 1/3 resampling is performed.
PrevLatency	Latency, in samples (any value >=0), which was left in the output signal by a previous process. Whole-number latency will be consumed by *this object while remaining fractional latency can be obtained via the getLatencyFrac() function.

Member Function Documentation

clear()

virtual void r8b::CDSPHBDownsampler::clear ( )

inlinevirtual

Function clears (resets) the state of *this object and returns it to the state after construction.

All input data accumulated in the internal buffer so far will be discarded.

Implements r8b::CDSPProcessor.

getLatency()

virtual int r8b::CDSPHBDownsampler::getLatency ( ) const

inlinevirtual

Returns

The latency, in samples, which is present in the output signal. This value is usually zero if the DSP processor "consumes" the latency automatically.

Implements r8b::CDSPProcessor.

getLatencyFrac()

virtual double r8b::CDSPHBDownsampler::getLatencyFrac ( ) const

inlinevirtual

Returns

Fractional latency, in samples, which is present in the output signal. This value is usually zero if a linear-phase filtering is used. With minimum-phase filters in use, this value can be non-zero even if the getLatency() function returns zero.

Implements r8b::CDSPProcessor.

getMaxOutLen()

virtual int r8b::CDSPHBDownsampler::getMaxOutLen ( const int  MaxInLen ) const

inlinevirtual

Parameters

MaxInLen

The number of samples planned to process at once, at most.

Returns

The maximal length of the output buffer required when processing the "MaxInLen" number of input samples.

Implements r8b::CDSPProcessor.

process()

virtual int r8b::CDSPHBDownsampler::process ( double *  ip, int  l0, double *&  op0  )

inlinevirtual

Function performs DSP processing.

Parameters

	ip	Input data pointer.
	l0	How many samples to process.
[out]	op0	Output data pointer. The capacity of this buffer should be equal to the value returned by the getMaxOutLen() function for the given "l0". This buffer can be equal to "ip" only if the getMaxOutLen( l0 ) function returned a value lesser than "l0". This pointer can be incremented on function's return if latency compensation was performed by the processor. Note that on function's return, this pointer may point to some internal buffers, including the "ip" buffer, ignoring the originally passed value.

Returns

The number of output samples written to the "op0" buffer and available after processing. This value can be smaller or larger in comparison to the original "l0" value due to processing and filter's latency compensation that took place, and due to resampling if it was performed.

Implements r8b::CDSPProcessor.

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

• src/r8brain/CDSPHBDownsampler.h