Aevalsrc

Audio Single output Source

Generate an audio signal generated by an expression.

FFmpeg filter: aevalsrc — the official reference.

Generate a stream. Aevalsrc is a source — it has no input, so you create a stream from it rather than applying it to one:

$audio = \FFmpeg\AudioStream::generate(new Aevalsrc(…));

apply() and addFilter() do not apply to source filters (there is nothing to attach them to).

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
exprs	string	—	—	set the ’|‘-separated list of channels expressions
nb_samples	int	1024	≥ 0	set the number of samples per requested frame
sample_rate	string	44100	—	set the sample rate
duration	int	-1	≥ -1	set audio duration
channel_layout	string	—	—	set channel layout

FFmpeg also names these options (use the parameter shown above): n → nb_samples, s → sample_rate, d → duration, c → channel_layout.

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