Filter dcshift
  Apply a DC shift to the audio.
    Inputs:
       #0: default (audio)
    Outputs:
       #0: default (audio)
dcshift AVOptions:
  shift             <double>     ..F.A.... set DC shift (from -1 to 1) (default 0)
  limitergain       <double>     ..F.A.... set limiter gain (from 0 to 1) (default 0)

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

