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 [40, 1080]. Default is 400.

h

Set channel height, allowed range is [1, 100]. Default is 20.

f

Set fade, allowed range is [1, 255]. Default is 20.

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.