Apply a low-pass filter with 3dB point frequency. The filter can be either single-pole or double-pole (the default). The filter roll off at 6dB per pole per octave (20dB per pole per decade).
The filter accepts the following options:
- frequency, f
-
Set frequency in Hz. Default is 500.
- poles, p
-
Set number of poles. Default is 2.
- width_type, t
-
Set method to specify band-width of filter.
- h
-
Hz
- q
-
Q-Factor
- o
-
octave
- s
-
slope
- k
-
kHz
- width, w
-
Specify the band-width of a filter in width_type units. Applies only to double-pole filter. The default is 0.707q and gives a Butterworth response.
- mix, m
-
How much to use filtered signal in output. Default is 1. Range is between 0 and 1.
- channels, c
-
Specify which channels to filter, by default all available are filtered.
Examples
-
Lowpass only LFE channel, it LFE is not present it does nothing:
lowpass=c=LFE
Commands
This filter supports the following commands:
- frequency, f
-
Change lowpass frequency. Syntax for the command is : "frequency"
- width_type, t
-
Change lowpass width_type. Syntax for the command is : "width_type"
- width, w
-
Change lowpass width. Syntax for the command is : "width"
- mix, m
-
Change lowpass mix. Syntax for the command is : "mix"