Afirsrc

Audio Single output Source

Generate a FIR coefficients audio stream.

FFmpeg filter: afirsrc — the official reference.

Generate a stream. Afirsrc 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 Afirsrc(…));

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
taps	int	1025	9–65535	set number of taps
frequency	string	0 1	—	set frequency points
magnitude	string	1 1	—	set magnitude values
phase	string	0 0	—	set phase values
sample_rate	int	44100	≥ 1	set sample rate
nb_samples	int	1024	≥ 1	set the number of samples per requested frame
win_func	AfirsrcWinFunc	blackman	rect, bartlett, hanning, hamming, blackman, welch, flattop, bharris, …	set window function

FFmpeg also names these options (use the parameter shown above): t → taps, f → frequency, m → magnitude, p → phase, r → sample_rate, n → nb_samples, w → win_func.

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