GstBtFilterSVF

GstBtFilterSVF — state variable filter

Functions

GstBtFilterSVF * gstbt_filter_svf_new ()
void gstbt_filter_svf_trigger ()
void gstbt_filter_svf_process ()

Properties

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

Types and Values

enum GstBtFilterSVFType
struct GstBtFilterSVF

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.

Owner: GstBtFilterSVF

Flags: Read / Write

Allowed values: [0,1]

Default value: 0.8

The “filter” property

  “filter”                   GstBtFilterSVFType

Type of audio filter.

Owner: GstBtFilterSVF

Flags: Read / Write

Default value: LowPass

The “resonance” property

  “resonance”                gdouble

Audio filter resonance.

Owner: GstBtFilterSVF

Flags: Read / Write

Allowed values: [0.7,25]

Default value: 0.8

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