GstBtFilterSVF

GstBtFilterSVF — state variable filter

Functions

Properties

gdouble cut-off Read / Write
GstBtFilterSVFType filter Read / Write
gdouble resonance Read / Write

Types and Values

Object Hierarchy

    GEnum
    ╰── GstBtFilterSVFType
    GObject
    ╰── GInitiallyUnowned
        ╰── GstObject
            ╰── GstBtFilterSVF

Includes

#include <libgstbuzztrax/filter-svf.h>

Description

An audio filter that can work in 4 modes (“filter”).

Filter modes

Frequency response of the filter with no resonance applied

low pass hi pass band pass band stop

Frequency response of the filter with resonance applied

low pass hi pass band pass band stop

The second graphs show that applying “resonance” when using GSTBT_FILTER_SVF_BANDSTOP mode does not make sense, as the resonance is filling the notch.

Functions

gstbt_filter_svf_new ()

GstBtFilterSVF *
gstbt_filter_svf_new (void);

Create a new instance

Returns

the new instance or NULL in case of an error


gstbt_filter_svf_trigger ()

void
gstbt_filter_svf_trigger (GstBtFilterSVF *self);

Reset filter state. Typically called for new notes.

Parameters

self

the filter

 

gstbt_filter_svf_process ()

void
gstbt_filter_svf_process (GstBtFilterSVF *self,
                          guint size,
                          gint16 *data);

Process size samples of audio from data and store them into data .

Parameters

self

the oscillator

 

size

number of sample to filter

 

data

buffer with the audio

 

Types and Values

enum GstBtFilterSVFType

Filter types.

Members

GSTBT_FILTER_SVF_NONE

no filtering

 

GSTBT_FILTER_SVF_LOWPASS

low pass

 

GSTBT_FILTER_SVF_HIPASS

high pass

 

GSTBT_FILTER_SVF_BANDPASS

band pass

 

GSTBT_FILTER_SVF_BANDSTOP

band stop (notch)

 

GSTBT_FILTER_SVF_COUNT

number of filter modes, this can change with new releases

 

struct GstBtFilterSVF

struct GstBtFilterSVF {
  /* parameters */
  GstBtFilterSVFType type;
  gdouble cutoff, resonance;
};

Class instance data.

Members

GstBtFilterSVFType type;

filter type

 

gdouble cutoff;

filter cutoff frequency

 

gdouble resonance;

filter resonance

 

Property Details

The “cut-off” property

  “cut-off”                  gdouble

Audio filter cut-off frequency.

Flags: Read / Write

Allowed values: [0,1]

Default value: 0.8


The “filter” property

  “filter”                   GstBtFilterSVFType

Type of audio filter.

Flags: Read / Write

Default value: LowPass


The “resonance” property

  “resonance”                gdouble

Audio filter resonance.

Flags: Read / Write

Allowed values: [0.7,25]

Default value: 0.8