Afftdn

Audio Single output Transform

Denoise audio samples using FFT.

FFmpeg filter: afftdn — the official reference.

Add it to a graph. The explicit form works for every filter — bind it to its input and read the result from outputs():

$node   = $audio->addFilter(new Afftdn(…));
$result = $node->outputs()[0];

Shorthand. Single-output filters can skip the node — apply() returns the result stream directly:

$result = $audio->apply(new Afftdn(…));

When to use it

TODO — when this filter shines: what it’s the right tool for, what to reach for instead when it isn’t, and how it composes with neighbouring filters.

How to use it

TODO — prose: how the filter actually works and what its key parameters mean (the explanation FFmpeg’s terse option help omits).

Examples

TODO — runnable PHP, with the equivalent ffmpeg CLI alongside.

Gotchas

TODO

See also

TODO

Parameters

Parameter	Type	Default	Range / values	Description
noise_reduction	float	12	0.01–97	set the noise reduction
noise_floor	float	-50	-80–-20	set the noise floor
noise_type	AfftdnType	white	white, vinyl, shellac, custom	set the noise type
band_noise	string	—	—	set the custom bands noise
residual_floor	float	-38	-80–-20	set the residual floor
track_noise	bool	false	—	track noise
track_residual	bool	false	—	track residual
output_mode	AfftdnMode	output	input, output, noise	set output mode
adaptivity	float	0.5	0–1	set adaptivity factor
floor_offset	float	1	-2–2	set noise floor offset factor
noise_link	AfftdnLink	min	none, min, max, average	set the noise floor link
band_multiplier	float	1.25	0.2–5	set band multiplier
sample_noise	AfftdnSample	none	none, start, stop	set sample noise mode
gain_smooth	int	0	0–50	set gain smooth radius

FFmpeg also names these options (use the parameter shown above): nr → noise_reduction, nf → noise_floor, nt → noise_type, bn → band_noise, rf → residual_floor, tn → track_noise, tr → track_residual, om → output_mode, ad → adaptivity, fo → floor_offset, nl → noise_link, bm → band_multiplier, sn → sample_noise, gs → gain_smooth.

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Maps to FFmpeg’s afftdn filter. Verified against ffmpeg n7.1.1.