Filter showvolume
  Convert input audio volume to video output.
    Inputs:
       #0: default (audio)
    Outputs:
       #0: default (video)
showvolume AVOptions:
  rate              <video_rate> ..FV...... set video rate (default "25")
  r                 <video_rate> ..FV...... set video rate (default "25")
  b                 <int>        ..FV...... set border width (from 0 to 5) (default 1)
  w                 <int>        ..FV...... set channel width (from 80 to 8192) (default 400)
  h                 <int>        ..FV...... set channel height (from 1 to 900) (default 20)
  f                 <double>     ..FV...... set fade (from 0 to 1) (default 0.95)
  c                 <string>     ..FV...... set volume color expression (default "PEAK*255+floor((1-PEAK)*255)*256+0xff000000")
  t                 <boolean>    ..FV...... display channel names (default true)
  v                 <boolean>    ..FV...... display volume value (default true)
  dm                <double>     ..FV...... duration for max value display (from 0 to 9000) (default 0)
  dmc               <color>      ..FV...... set color of the max value line (default "orange")
  o                 <int>        ..FV...... set orientation (from 0 to 1) (default h)
     h               0            ..FV...... horizontal
     v               1            ..FV...... vertical
  s                 <int>        ..FV...... set step size (from 0 to 5) (default 0)
  p                 <float>      ..FV...... set background opacity (from 0 to 1) (default 0)
  m                 <int>        ..FV...... set mode (from 0 to 1) (default p)
     p               0            ..FV...... peak
     r               1            ..FV...... rms
  ds                <int>        ..FV...... set display scale (from 0 to 1) (default lin)
     lin             0            ..FV...... linear
     log             1            ..FV...... log


