Speechnorm

Audio Single output Transform

Speech Normalizer.

FFmpeg filter: speechnorm — 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 Speechnorm(…));
$result = $node->outputs()[0];

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

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

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
peak	float	0.95	0–1	set the peak value
expansion	float	2	1–50	set the max expansion factor
compression	float	2	1–50	set the max compression factor
threshold	float	0	0–1	set the threshold value
raise	float	0.001	0–1	set the expansion raising amount
fall	float	0.001	0–1	set the compression raising amount
channels	string	all	—	set channels to filter
invert	bool	false	—	set inverted filtering
link	bool	false	—	set linked channels filtering
rms	float	0	0–1	set the RMS value

FFmpeg also names these options (use the parameter shown above): p → peak, e → expansion, c → compression, t → threshold, r → raise, f → fall, h → channels, i → invert, l → link, m → rms.

---

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