Filter eq
  Adjust brightness, contrast, gamma, and saturation.
    Inputs:
       #0: default (video)
    Outputs:
       #0: default (video)
eq AVOptions:
  contrast          <string>     ..FV..... set the contrast adjustment, negative values give a negative image (default "1.0")
  brightness        <string>     ..FV..... set the brightness adjustment (default "0.0")
  saturation        <string>     ..FV..... set the saturation adjustment (default "1.0")
  gamma             <string>     ..FV..... set the initial gamma value (default "1.0")
  gamma_r           <string>     ..FV..... gamma value for red (default "1.0")
  gamma_g           <string>     ..FV..... gamma value for green (default "1.0")
  gamma_b           <string>     ..FV..... gamma value for blue (default "1.0")
  gamma_weight      <string>     ..FV..... set the gamma weight which reduces the effect of gamma on bright areas (default "1.0")
  eval              <int>        ..FV..... specify when to evaluate expressions (from 0 to 1) (default init)
     init            0            ..FV..... eval expressions once during initialization
     frame           1            ..FV..... eval expressions per-frame

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

