SpectrumSettings class final

Configuration for the real-time FFT spectrum + raw PCM streams.

Apply atomically via Player.setSpectrum (replace the whole bundle) or Player.updateSpectrum (mutate one or more fields with a copyWith mapper). Read live via PlayerStream.spectrum and PlayerStream.pcm.

The streams are lazy — the FFT pipeline allocates and the FFI poll loop starts only on the first listener, and tears down on the last cancel. A subscriber to either PlayerStream.spectrum or PlayerStream.pcm alone is enough to arm the pipeline; both streams share the same upstream tap.

Default values pick a balanced "music visualizer" preset: 2048-point Hann FFT at 30 Hz emit rate, log-spaced 64 bands from 20 Hz to 20 kHz, asymmetric EMA (fast attack, slow decay) and a [-70, -10] dB clip range that looks lively on most music. Tweak from there.

Constructors

SpectrumSettings({int fftSize = 2048, int bandCount = 64, double bandLowHz = 20.0, double bandHighHz = 20000.0, WindowFunction window = WindowFunction.hann, Duration emitInterval = const Duration(milliseconds: 33), double attackSmoothing = 0.5, double releaseSmoothing = 0.1, double minDb = -70.0, double maxDb = -10.0})

const

Properties

attackSmoothing → double

EMA smoothing coefficient applied when a band's new value is higher than the previous frame. Range [0, 1]; higher = snappier attack. 0.5 default — visualizer pops with transients (kicks, snare hits) without flickering on noise.

final

bandCount → int

Number of perceptual bands the FftFrame.bands field is bucketed into. Typical 32 / 64 / 128. Bands are log-spaced from bandLowHz to bandHighHz — geometric edges, ratio (bandHighHz / bandLowHz)^(1 / bandCount) per band.

final

bandHighHz → double

Upper edge of the band axis, in Hz. Default 20 kHz (top of human hearing). Clamped at FFT time to the Nyquist limit (sampleRate / 2).

final

bandLowHz → double

Lower edge of the band axis, in Hz. Default 20 Hz (bottom of human hearing).

final

emitInterval → Duration

Time between FftFrame / PcmFrame emissions. 33 ms ≈ 30 fps (default), 16 ms ≈ 60 fps. Range 8 ms (~120 fps) to 67 ms (~15 fps); the pipeline is gated by this independently of the FFT block rate.

final

fftSize → int

FFT size in samples. Power of 2 between 256 and 4096. Larger = better frequency resolution at the cost of time resolution (a 2048-point FFT @ 48 kHz spans 42.7 ms of audio). 2048 is the visualizer sweet spot — sub-50 Hz resolution to separate kick fundamentals from sub-bass, latency below the ~80 ms A/V sync threshold.

final

hashCode → int

The hash code for this object.

no setter, override

maxDb → double

Upper edge of the dB clip range mapped to band value 1.0. Anything above maxDb saturates at 1.0. -10 dB default — the visualizer hits full scale on loud peaks before digital clipping.

final

minDb → double

Lower edge of the dB clip range mapped to band value 0.0. Anything below minDb reads as silent. -70 dB default — leaves some "lift" in the visualizer for quiet passages.

final

releaseSmoothing → double

EMA smoothing coefficient applied when a band's new value is lower than the previous frame. Range [0, 1]; lower = slower decay ("afterglow"). 0.1 default. Asymmetric attack / release is the standard choice — symmetric EMA is simultaneously sluggish on transients AND jittery on decays.

final

runtimeType → Type

A representation of the runtime type of the object.

no setter, inherited

window → WindowFunction

Window function applied to each FFT block before transform. See WindowFunction for the trade-offs. Default Hann is the universal music-visualizer choice.

final

Methods

copyWith({int? fftSize, int? bandCount, double? bandLowHz, double? bandHighHz, WindowFunction? window, Duration? emitInterval, double? attackSmoothing, double? releaseSmoothing, double? minDb, double? maxDb}) → SpectrumSettings

noSuchMethod(Invocation invocation) → dynamic

Invoked when a nonexistent method or property is accessed.

inherited

toString() → String

A string representation of this object.

override

Operators

operator ==(Object other) → bool

The equality operator.

override

Constants

defaults → const SpectrumSettings

Default visualizer preset — 2048 Hann FFT at 30 fps with 64 log-spaced bands. Convenience setSpectrum(SpectrumSettings.defaults) to reset.