## audiochebband

audiochebband — Chebyshev band pass and band reject filter

## Properties

gfloat | lower-frequency | Read / Write
GstAudioChebBandMode | mode | Read / Write
gint | poles | Read / Write
gfloat | ripple | Read / Write
gint | type | Read / Write
gfloat | upper-frequency | Read / Write

## Types and Values

struct | GstAudioChebBand

## Object Hierarchy

        GObject
        ╰── GInitiallyUnowned
            ╰── GstObject
                ╰── GstElement
                    ╰── GstBaseTransform
                        ╰── GstAudioFilter
                            ╰── GstAudioFXBaseIIRFilter
                                ╰── GstAudioChebBand

## Description

Attenuates all frequencies outside (bandpass) or inside (bandreject) of a frequency band. The number of poles and the ripple parameter control the rolloff.

This element has the advantage over the windowed sinc bandpass and bandreject filter that it is much faster and produces almost as good results. It's only disadvantages are the highly non-linear phase and the slower rolloff compared to a windowed sinc filter with a large kernel.

For type 1 the ripple parameter specifies how much ripple in dB is allowed in the passband, i.e. some frequencies in the passband will be amplified by that value. A higher ripple value will allow a faster rolloff.

For type 2 the ripple parameter specifies the stopband attenuation. In the stopband the gain will be at most this value. A lower ripple value will allow a faster rolloff.

As a special case, a Chebyshev type 1 filter with no ripple is a Butterworth filter.

Be warned that a too large number of poles can produce noise. The most poles are possible with a cutoff frequency at a quarter of the sampling rate.

### Example launch line

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    gst-launch-1.0 audiotestsrc freq=1500 ! audioconvert ! audiochebband mode=band-pass lower-frequency=1000 upper-frequenc=6000 poles=4 ! audioconvert ! alsasink
    gst-launch-1.0 filesrc location="melo1.ogg" ! oggdemux ! vorbisdec ! audioconvert ! audiochebband mode=band-reject lower-frequency=1000 upper-frequency=4000 ripple=0.2 ! audioconvert ! alsasink
    gst-launch-1.0 audiotestsrc wave=white-noise ! audioconvert ! audiochebband mode=band-pass lower-frequency=1000 upper-frequency=4000 type=2 ! audioconvert ! alsasink

## Synopsis

### Element Information

plugin | audiofx
author | Sebastian Dröge <sebastian.droege@collabora.co.uk>
class | Filter/Effect/Audio

### Element Pads

name | sink
direction | sink
presence | always
details | audio/x-raw, format=(string){ F32LE, F64LE }, rate=(int)[ 1, 2147483647 ], channels=(int)[ 1, 2147483647 ], layout=(string)interleaved

name | src
direction | source
presence | always
details | audio/x-raw, format=(string){ F32LE, F64LE }, rate=(int)[ 1, 2147483647 ], channels=(int)[ 1, 2147483647 ], layout=(string)interleaved

## Functions

## Types and Values

### struct GstAudioChebBand

    struct GstAudioChebBand;

## Property Details

### The `“lower-frequency”` property

      “lower-frequency”          gfloat

Start frequency of the band (Hz).

Flags: Read / Write

Allowed values: [0,100000]

Default value: 0

### The `“mode”` property

      “mode”                     GstAudioChebBandMode

Low pass or high pass mode.

Flags: Read / Write

Default value: Band pass (default)

### The `“poles”` property

      “poles”                    gint

Number of poles to use, will be rounded up to the next multiply of four.

Flags: Read / Write

Allowed values: [4,32]

Default value: 4

### The `“ripple”` property

      “ripple”                   gfloat

Amount of ripple (dB).

Flags: Read / Write

Allowed values: [0,200]

Default value: 0.25

### The `“type”` property

      “type”                     gint

Type of the chebychev filter.

Flags: Read / Write

Allowed values: [1,2]

Default value: 1

### The `“upper-frequency”` property

      “upper-frequency”          gfloat

Stop frequency of the band (Hz).

Flags: Read / Write

Allowed values: [0,100000]

Default value: 0