Generic Filter

class gpype.backend.filters.base.generic_filter.GenericFilter

Bases: IONode

Generic Linear Time-Invariant (LTI) digital filter for real-time use.

Implements a flexible LTI filter using transfer function coefficients (numerator ‘b’ and denominator ‘a’ polynomials). For IIR filters, converts to second-order sections for numerical stability. For FIR filters, uses direct form implementation to avoid unnecessary decomposition overhead. Maintains state for streaming data.

class Configuration

Bases: Configuration

Configuration class for GenericFilter parameters.

class Keys

Bases: Keys

Configuration keys for filter coefficients.

B = 'b'

Numerator coefficients configuration key

A = 'a'

Denominator coefficients configuration key

__init__(b=None, a=None, **kwargs)

Initialize the generic filter with transfer function coefficients.

Parameters:

• b (ndarray) – Numerator coefficients of the transfer function.

• a (ndarray) – Denominator coefficients of the transfer function.

• **kwargs – Additional arguments passed to parent IONode class.

Raises:

ValueError – If coefficients are empty or invalid.

setup(data, port_context_in)

Setup the generic filter before processing begins.

Converts transfer function to second-order sections for numerical stability and initializes filter state based on channel configuration.

Parameters:

• data (dict[str, ndarray]) – Initial data dictionary (not used in setup).

• port_context_in (dict[str, dict]) – Input port context containing channel_count and other metadata.

Return type:

dict[str, dict]

Returns:

Output port context dictionary with updated metadata.

Raises:

ValueError – If required context keys are missing or coefficients are invalid.

step(data)

Apply the generic filter to input data.

Processes input data through the filter while maintaining filter state for continuous operation across processing steps.

Parameters:

data (dict[str, ndarray]) – Dictionary containing input data with key PORT_IN. Input should be 2D array (samples x channels).

Return type:

dict[str, ndarray]

Returns:

Dictionary with filtered data under key PORT_OUT.

Raises:

ValueError – If input data is not 2D array.