vital::FirHalfbandDecimator Class Reference

A FIR half-band decimator for downsampling audio by a factor of 2. More...

#include <fir_halfband_decimator.h>

Inheritance diagram for vital::FirHalfbandDecimator:

Public Types
enum	{ kAudio , kNumInputs }

Public Member Functions
	FirHalfbandDecimator ()
	Constructs a FirHalfbandDecimator and initializes taps.
virtual	~FirHalfbandDecimator ()
	Virtual destructor.
virtual Processor *	clone () const override
	Clones (deep copies) this decimator.
void	saveMemory (int num_samples)
	Saves the last few samples of audio to memory, preparing for the next processing block.
virtual void	process (int num_samples) override
	Processes the input audio by decimating it, producing half the number of output samples.
Public Member Functions inherited from vital::Processor
	Processor (int num_inputs, int num_outputs, bool control_rate=false, int max_oversample=1)
	Constructs a Processor with a given number of inputs/outputs and oversampling.
virtual	~Processor ()
	Virtual destructor.
virtual bool	hasState () const
	Indicates whether this Processor requires per-voice state.
virtual void	processWithInput (const poly_float *audio_in, int num_samples)
	An optional processing function taking explicit input buffer. Fallback is an assertion failure (not supported).
virtual void	init ()
	Called after constructor, used for any additional initialization. Subclasses can override. Sets the initialized flag.
virtual void	hardReset ()
	Called to perform a "hard" reset for all voices.
bool	initialized ()
	Returns whether this Processor has been initialized.
virtual void	setSampleRate (int sample_rate)
	Updates the sample rate of this Processor (scaled by oversampling).
virtual void	setOversampleAmount (int oversample)
	Sets the oversampling amount and updates the effective sample rate.
force_inline bool	enabled () const
	Checks if this Processor is enabled.
virtual void	enable (bool enable)
	Enables or disables this Processor.
force_inline int	getSampleRate () const
	Retrieves the current (effective) sample rate.
force_inline int	getOversampleAmount () const
	Retrieves the current oversampling factor.
force_inline bool	isControlRate () const
	Checks if this Processor is running at control rate (buffer_size == 1).
virtual void	setControlRate (bool control_rate)
	Sets whether this Processor runs at control rate.
force_inline poly_mask	getResetMask (int input_index) const
	Retrieves a mask indicating which voices triggered a note-on event. Compares the input's trigger_value to kVoiceOn.
force_inline void	clearOutputBufferForReset (poly_mask reset_mask, int input_index, int output_index) const
	Clears output samples for voices that are about to be reset, based on the trigger offset.
bool	inputMatchesBufferSize (int input=0)
	Checks whether the buffer size of a particular input matches the size needed by this Processor.
bool	checkInputAndOutputSize (int num_samples)
	Checks if all inputs and outputs have buffers big enough for num_samples.
virtual bool	isPolyphonic () const
	Checks if this Processor is polyphonic by querying its ProcessorRouter.
void	plug (const Output *source)
	Connects an external Output to this Processor's first input.
void	plug (const Output *source, unsigned int input_index)
	Connects an external Output to a specified input index.
void	plug (const Processor *source)
	Connects the first output of a Processor to this Processor's first input.
void	plug (const Processor *source, unsigned int input_index)
	Connects the first output of a Processor to a specified input index.
void	plugNext (const Output *source)
	Connects an external Output to the first available (unplugged) input.
void	plugNext (const Processor *source)
	Connects the first output of a Processor to the first available (unplugged) input.
void	useInput (Input *input)
	Uses an existing Input object as this Processor's first input.
void	useInput (Input *input, int index)
	Uses an existing Input object at a specified input index.
void	useOutput (Output *output)
	Uses an existing Output object as this Processor's first output.
void	useOutput (Output *output, int index)
	Uses an existing Output object at a specified output index.
int	connectedInputs ()
	Counts how many inputs are connected to a real source (not null_source_).
virtual void	unplugIndex (unsigned int input_index)
	Removes the connection at a specified input index, if any.
virtual void	unplug (const Output *source)
	Removes a connection to a given Output from all inputs.
virtual void	unplug (const Processor *source)
	Removes connections to all outputs from a given Processor.
virtual void	numInputsChanged ()
	Called when the number of inputs changes (e.g., new connections). Subclasses may override for dynamic behavior.
force_inline void	router (ProcessorRouter *router)
	Sets the ProcessorRouter that owns or manages this Processor.
force_inline ProcessorRouter *	router () const
	Returns the ProcessorRouter that currently owns this Processor.
ProcessorRouter *	getTopLevelRouter () const
	Gets the topmost (root) ProcessorRouter by traversing parent routers.
virtual void	registerInput (Input *input, int index)
	Registers a new input, appending it to the input list.
virtual Output *	registerOutput (Output *output, int index)
	Registers a new Output in the output list at a specified index.
virtual void	registerInput (Input *input)
	Registers a new Input by appending it to the end of the input list.
virtual Output *	registerOutput (Output *output)
	Registers a new Output by appending it to the end of the output list.
force_inline int	numInputs () const
	Returns the total number of Input pointers (owned or otherwise).
force_inline int	numOutputs () const
	Returns the total number of Output pointers (owned or otherwise).
force_inline int	numOwnedInputs () const
	Returns how many Input objects this Processor owns.
force_inline int	numOwnedOutputs () const
	Returns how many Output objects this Processor owns.
force_inline Input *	input (unsigned int index=0) const
	Retrieves the Input pointer at a given index.
force_inline bool	isInputSourcePolyphonic (int index=0)
	Checks if the input source at a given index is polyphonic.
force_inline Input *	ownedInput (unsigned int index=0) const
	Retrieves an owned Input pointer at a given index.
force_inline Output *	output (unsigned int index=0) const
	Retrieves the Output pointer at a given index.
force_inline Output *	ownedOutput (unsigned int index=0) const
	Retrieves an owned Output pointer at a given index.
void	setPluggingStart (int start)
	Sets the position at which plugNext starts searching for an open input.

Static Public Attributes
static constexpr int	kNumTaps = 32
	Number of FIR taps in the filter.

Additional Inherited Members
Protected Member Functions inherited from vital::Processor
Output *	addOutput (int oversample=1)
	Creates and registers a new Output. Handles control rate vs. audio rate.
Input *	addInput ()
	Creates and registers a new Input, initially connected to null_source_.
Protected Attributes inherited from vital::Processor
std::shared_ptr< ProcessorState >	state_
	Shared state (sample rate, oversample, etc.)
int	plugging_start_
	The index at which plugNext starts searching for an unplugged input.
std::vector< std::shared_ptr< Input > >	owned_inputs_
	Inputs owned by this Processor.
std::vector< std::shared_ptr< Output > >	owned_outputs_
	Outputs owned by this Processor.
std::shared_ptr< std::vector< Input * > >	inputs_
	All inputs, owned or external.
std::shared_ptr< std::vector< Output * > >	outputs_
	All outputs, owned or external.
ProcessorRouter *	router_
	The ProcessorRouter that manages this Processor.
Static Protected Attributes inherited from vital::Processor
static const Output	null_source_
	A null (dummy) source used for unconnected inputs.

Detailed Description

A FIR half-band decimator for downsampling audio by a factor of 2.

This decimator uses a half-band FIR filter to combine every pair of input samples into a single output sample, reducing the sample rate by half.

Member Enumeration Documentation

anonymous enum

anonymous enum

Enumerator
kAudio	The main audio input.
kNumInputs	Total number of inputs for this processor.

Constructor & Destructor Documentation

FirHalfbandDecimator()

vital::FirHalfbandDecimator::FirHalfbandDecimator

(

)

Constructs a FirHalfbandDecimator and initializes taps.

Constructs the FirHalfbandDecimator, setting up FIR coefficients and resetting memory.

Sets up the filter coefficients and resets the internal memory.

The static array coefficients stores the full 32 taps. Half (kNumTaps/2) are packed into each element of taps_ as a poly_float, allowing pairwise processing in the decimation loop.

~FirHalfbandDecimator()

virtual vital::FirHalfbandDecimator::~FirHalfbandDecimator ( )

inlinevirtual

Virtual destructor.

Member Function Documentation

clone()

virtual Processor * vital::FirHalfbandDecimator::clone ( ) const

inlineoverridevirtual

Clones (deep copies) this decimator.

Returns

A pointer to a new FirHalfbandDecimator instance.

Implements vital::Processor.

process()

void vital::FirHalfbandDecimator::process ( int num_samples )

overridevirtual

Processes the input audio by decimating it, producing half the number of output samples.

Processes the audio by decimating it (reducing sample rate by half) using a half-band FIR filter.

Parameters

num_samples	The number of output samples to produce. (The input must be 2 * num_samples in length.)
num_samples	The number of output samples to produce. The input must have 2 * num_samples samples.

For each output sample, the filter sums products of input samples and filter coefficients, then uses the utils::sumSplitAudio() function to sum the two lanes of the poly_float result.

Implements vital::Processor.

saveMemory()

void vital::FirHalfbandDecimator::saveMemory

(

int

num_samples

)

Saves the last few samples of audio to memory, preparing for the next processing block.

Saves samples from the tail of the current processing block to memory, so the filter can continue seamlessly.

Parameters

num_samples

The number of samples that were processed in this block (i.e., half the input buffer size).

This function stores samples that will be needed by subsequent processing blocks.

Parameters

num_samples

The number of output samples processed in this block (the input is 2 * num_samples).

This function copies the last few input samples into the memory_ array to be used as the first samples in the next block's processing. This prevents discontinuities at block boundaries.

Member Data Documentation

kNumTaps

int vital::FirHalfbandDecimator::kNumTaps = 32

staticconstexpr

Number of FIR taps in the filter.

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

• /Users/davidvogel/repos/VitalHelp/src/synthesis/filters/fir_halfband_decimator.h
• /Users/davidvogel/repos/VitalHelp/src/synthesis/filters/fir_halfband_decimator.cpp