r8b::CDSPFracInterpolator Class Reference

Fractional delay filter bank-based interpolator class. More...

#include <CDSPFracInterpolator.h>

Inheritance diagram for r8b::CDSPFracInterpolator:

Collaboration diagram for r8b::CDSPFracInterpolator:

Public Member Functions
	CDSPFracInterpolator (const double aSrcSampleRate, const double aDstSampleRate, const double ReqAtten, const bool IsThird, const double PrevLatency)
	Constructor initalizes the interpolator. 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

Fractional delay filter bank-based interpolator class.

Class implements the fractional delay interpolator. This implementation at first puts the input signal into a ring buffer and then performs interpolation. The interpolation is performed using sinc-based fractional delay filters. These filters are contained in a bank, and for higher precision they are interpolated between adjacent filters.

To increase sample timing precision, this class uses "resettable counter" approach. This gives zero overall sample timing error. With the R8B_FASTTIMING configuration option enabled, the sample timing experiences a very minor drift.

Constructor & Destructor Documentation

CDSPFracInterpolator()

r8b::CDSPFracInterpolator::CDSPFracInterpolator ( const double  aSrcSampleRate, const double  aDstSampleRate, const double  ReqAtten, const bool  IsThird, const double  PrevLatency  )

inline

Constructor initalizes the interpolator.

It is important to call the getMaxOutLen() function afterwards to obtain the optimal output buffer length.

Parameters

aSrcSampleRate	Source sample rate.
aDstSampleRate	Destination sample rate.
ReqAtten	Required filter attentuation.
IsThird	"True" if one-third filter is required.
PrevLatency	Latency, in samples (any value >=0), which was left in the output signal by a previous process. This latency will be consumed completely.

Member Function Documentation

clear()

virtual void r8b::CDSPFracInterpolator::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::CDSPFracInterpolator::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::CDSPFracInterpolator::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::CDSPFracInterpolator::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::CDSPFracInterpolator::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/CDSPFracInterpolator.h