Filter agate
  Audio gate.
    Inputs:
       #0: default (audio)
    Outputs:
       #0: default (audio)
agate AVOptions:
  level_in          <double>     ..F.A....T set input level (from 0.015625 to 64) (default 1)
  mode              <int>        ..F.A....T set mode (from 0 to 1) (default downward)
     downward        0            ..F.A....T
     upward          1            ..F.A....T
  range             <double>     ..F.A....T set max gain reduction (from 0 to 1) (default 0.06125)
  threshold         <double>     ..F.A....T set threshold (from 0 to 1) (default 0.125)
  ratio             <double>     ..F.A....T set ratio (from 1 to 9000) (default 2)
  attack            <double>     ..F.A....T set attack (from 0.01 to 9000) (default 20)
  release           <double>     ..F.A....T set release (from 0.01 to 9000) (default 250)
  makeup            <double>     ..F.A....T set makeup gain (from 1 to 64) (default 1)
  knee              <double>     ..F.A....T set knee (from 1 to 8) (default 2.82843)
  detection         <int>        ..F.A....T set detection (from 0 to 1) (default rms)
     peak            0            ..F.A....T
     rms             1            ..F.A....T
  link              <int>        ..F.A....T set link (from 0 to 1) (default average)
     average         0            ..F.A....T
     maximum         1            ..F.A....T
  level_sc          <double>     ..F.A....T set sidechain gain (from 0.015625 to 64) (default 1)

This filter has support for timeline through the 'enable' option.

