Showcqt

Audio Video Single output Transform

Convert input audio to a CQT (Constant/Clamped Q Transform) spectrum video output.

FFmpeg filter: showcqt — 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   = $video->addFilter(new Showcqt(…));
$result = $node->outputs()[0];

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

$result = $video->apply(new Showcqt(…));

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
size	string	1920x1080	—	set video size
rate	string	25	—	set video rate
bar_h	int	-1	≥ -1	set bargraph height
axis_h	int	-1	≥ -1	set axis height
sono_h	int	-1	≥ -1	set sonogram height
fullhd	bool	true	—	set fullhd size
sono_v	string	16	—	set sonogram volume
volume2	string	sono_v	—	set bargraph volume
sono_g	float	3	1–7	set sonogram gamma
gamma2	float	1	1–7	set bargraph gamma
bar_t	float	1	0–1	set bar transparency
timeclamp	float	0.17	0.002–1	set timeclamp
attack	float	0	0–1	set attack time
basefreq	float	20.01523126408	10–100000	set base frequency
endfreq	float	20495.596814418	10–100000	set end frequency
coeffclamp	float	1	0.1–10	set coeffclamp
tlength	string	384*tc/(384+tc*f)	—	set tlength
count	int	6	1–30	set transform count
fcount	int	0	0–10	set frequency count
fontfile	string	—	—	set axis font file
font	string	—	—	set axis font
fontcolor	string	st(0, (midi(f)-59.5)/12);st(1, if(between(ld(0),0,1), 0.5-0.5*cos(2*PI*ld(0)), 0));r(1-ld(1)) + b(ld(1))	—	set font color
axisfile	string	—	—	set axis image
axis	bool	true	—	draw axis
csp	ShowcqtCsp	unspecified	unspecified, bt709, fcc, bt470bg, smpte170m, smpte240m, bt2020ncl	set color space
cscheme	string	1|0.5|0|0|0.5|1	—	set color scheme

FFmpeg also names these options (use the parameter shown above): s → size, fps → rate, r → rate, volume → sono_v, bar_v → volume2, gamma → sono_g, bar_g → gamma2, tc → timeclamp, text → axis.

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