Aemphasis

Audio Single output Transform

Audio emphasis.

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

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

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

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
level_in	float	1	0–64	set input gain
level_out	float	1	0–64	set output gain
mode	AemphasisMode	reproduction	reproduction, production	set filter mode
type	AemphasisType	cd	col, emi, bsi, riaa, cd, 50fm, 75fm, 50kf, …	set filter type

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