Filter afir
  Apply Finite Impulse Response filter with supplied coefficients in 2nd stream.
    slice threading supported
    Inputs:
       #0: main (audio)
       #1: ir (audio)
    Outputs:
        dynamic (depending on the options)
afir AVOptions:
  dry               <float>      ..F.A.... set dry gain (from 0 to 10) (default 1)
  wet               <float>      ..F.A.... set wet gain (from 0 to 10) (default 1)
  length            <float>      ..F.A.... set IR length (from 0 to 1) (default 1)
  gtype             <int>        ..F.A.... set IR auto gain type (from -1 to 2) (default peak)
     none            -1           ..F.A.... without auto gain
     peak            0            ..F.A.... peak gain
     dc              1            ..F.A.... DC gain
     gn              2            ..F.A.... gain to noise
  irgain            <float>      ..F.A.... set IR gain (from 0 to 1) (default 1)
  irfmt             <int>        ..F.A.... set IR format (from 0 to 1) (default input)
     mono            0            ..F.A.... single channel
     input           1            ..F.A.... same as input
  maxir             <float>      ..F.A.... set max IR length (from 0.1 to 60) (default 30)
  response          <boolean>    ..FV..... show IR frequency response (default false)
  channel           <int>        ..FV..... set IR channel to display frequency response (from 0 to 1024) (default 0)
  size              <image_size> ..FV..... set video size (default "hd720")
  rate              <video_rate> ..FV..... set video rate (default "25")
  minp              <int>        ..F.A.... set min partition size (from 8 to 32768) (default 8192)
  maxp              <int>        ..F.A.... set max partition size (from 8 to 32768) (default 8192)


