Filter ahistogram
  Convert input audio to histogram video output.
    Inputs:
       #0: default (audio)
    Outputs:
       #0: default (video)
ahistogram AVOptions:
  dmode             <int>        ..FV..... set method to display channels (from 0 to 1) (default single)
     single          0            ..FV..... all channels use single histogram
     separate        1            ..FV..... each channel have own histogram
  rate              <video_rate> ..FV..... set video rate (default "25")
  r                 <video_rate> ..FV..... set video rate (default "25")
  size              <image_size> ..FV..... set video size (default "hd720")
  s                 <image_size> ..FV..... set video size (default "hd720")
  scale             <int>        ..FV..... set display scale (from 0 to 4) (default log)
     log             3            ..FV..... logarithmic
     sqrt            1            ..FV..... square root
     cbrt            2            ..FV..... cubic root
     lin             0            ..FV..... linear
     rlog            4            ..FV..... reverse logarithmic
  ascale            <int>        ..FV..... set amplitude scale (from 0 to 1) (default log)
     log             1            ..FV..... logarithmic
     lin             0            ..FV..... linear
  acount            <int>        ..FV..... how much frames to accumulate (from -1 to 100) (default 1)
  rheight           <float>      ..FV..... set histogram ratio of window height (from 0 to 1) (default 0.1)
  slide             <int>        ..FV..... set sonogram sliding (from 0 to 1) (default replace)
     replace         0            ..FV..... replace old rows with new
     scroll          1            ..FV..... scroll from top to bottom


