Convert input audio volume to a video output.

The filter accepts the following options:

rate, r

Set video rate.

b

Set border width, allowed range is [0, 5]. Default is 1.

w

Set channel width, allowed range is [80, 8192]. Default is 400.

h

Set channel height, allowed range is [1, 900]. Default is 20.

f

Set fade, allowed range is [0.001, 1]. Default is 0.95.

c

Set volume color expression.

The expression can use the following variables:

VOLUME

Current max volume of channel in dB.

CHANNEL

Current channel number, starting from 0.

t

If set, displays channel names. Default is enabled.

v

If set, displays volume values. Default is enabled.

o

Set orientation, can be horizontal or vertical, default is horizontal.

s

Set step size, allowed range s [0, 5]. Default is 0, which means step is disabled.