Class CrossfadingBiQuadFilter

Namespace

NAudio.Dsp

Assembly

NAudio.Core.dll

Wraps two BiQuadFilter instances to retune a running filter without the click an in-place coefficient change causes. BiQuadFilter deliberately resets its state on every coefficient change (to recover from a divergent NaN/Inf run), so retuning it in place is discontinuous. Instead, reconfigure the Standby filter to the new settings, call BeginCrossfade(), and the output linearly crossfades from the old response to the new one over a short window.

public sealed class CrossfadingBiQuadFilter

Inheritance

object

CrossfadingBiQuadFilter

Inherited Members

object.Equals(object)

object.Equals(object, object)

object.GetHashCode()

object.GetType()

object.ReferenceEquals(object, object)

object.ToString()

Constructors

CrossfadingBiQuadFilter(BiQuadFilter, BiQuadFilter, int)

Creates a crossfading filter from an initially-audible active filter and a standby filter (a second instance used to stage the next set of coefficients). Both are created by the caller through the public BiQuadFilter factory methods.

public CrossfadingBiQuadFilter(BiQuadFilter active, BiQuadFilter standby, int crossfadeSamples)

Parameters

active BiQuadFilter

The filter that is initially audible.

standby BiQuadFilter

A second filter instance used to stage the next settings.

crossfadeSamples int

Length of the retune crossfade in samples. Must be at least 1.

Properties

IsCrossfading

True while a retune crossfade is in progress.

public bool IsCrossfading { get; }

Property Value

bool

Standby

The filter that stages the next settings. Reconfigure this (via its Set… methods) before calling BeginCrossfade(), or replace it wholesale with ReplaceStandby(BiQuadFilter) for filter shapes that have no in-place setter (shelves, notch, band-pass, all-pass).

public BiQuadFilter Standby { get; }

Property Value

BiQuadFilter

Methods

BeginCrossfade()

Starts crossfading from the currently-audible filter to the Standby filter. If a crossfade is already running it restarts from the beginning; the output stays continuous because both filters are run.

public void BeginCrossfade()

Process(Span<float>)

Processes a block of samples in place.

public void Process(Span<float> buffer)

Parameters

buffer Span<float>

ReplaceStandby(BiQuadFilter)

Swaps in a freshly-built filter as the next settings. Use this when retuning to a shape that has no in-place Set… method (build it with the BiQuadFilter factories), then call BeginCrossfade(). Intended for parameter-change events, not the audio thread's steady state.

public void ReplaceStandby(BiQuadFilter filter)

Parameters

filter BiQuadFilter

Reset()

Cancels any crossfade in progress and clears both wrapped filters' sample history, so the next input is filtered as if from silence. Coefficients are left unchanged.

public void Reset()

Transform(float)

Processes one sample.

public float Transform(float input)

Parameters

input float

Returns

float