Filter acrossfade
  Cross fade two input audio streams.
    Inputs:
       #0: crossfade0 (audio)
       #1: crossfade1 (audio)
    Outputs:
       #0: default (audio)
acrossfade AVOptions:
  nb_samples        <int>        ..F.A.... set number of samples for cross fade duration (from 1 to 2.14748e+008) (default 44100)
  ns                <int>        ..F.A.... set number of samples for cross fade duration (from 1 to 2.14748e+008) (default 44100)
  duration          <duration>   ..F.A.... set cross fade duration (default 0)
  d                 <duration>   ..F.A.... set cross fade duration (default 0)
  overlap           <boolean>    ..F.A.... overlap 1st stream end with 2nd stream start (default true)
  o                 <boolean>    ..F.A.... overlap 1st stream end with 2nd stream start (default true)
  curve1            <int>        ..F.A.... set fade curve type for 1st stream (from 0 to 17) (default tri)
     tri                          ..F.A.... linear slope
     qsin                         ..F.A.... quarter of sine wave
     esin                         ..F.A.... exponential sine wave
     hsin                         ..F.A.... half of sine wave
     log                          ..F.A.... logarithmic
     ipar                         ..F.A.... inverted parabola
     qua                          ..F.A.... quadratic
     cub                          ..F.A.... cubic
     squ                          ..F.A.... square root
     cbr                          ..F.A.... cubic root
     par                          ..F.A.... parabola
     exp                          ..F.A.... exponential
     iqsin                        ..F.A.... inverted quarter of sine wave
     ihsin                        ..F.A.... inverted half of sine wave
     dese                         ..F.A.... double-exponential seat
     desi                         ..F.A.... double-exponential sigmoid
     losi                         ..F.A.... logistic sigmoid
     nofade                       ..F.A.... no fade; keep audio as-is
  c1                <int>        ..F.A.... set fade curve type for 1st stream (from 0 to 17) (default tri)
     tri                          ..F.A.... linear slope
     qsin                         ..F.A.... quarter of sine wave
     esin                         ..F.A.... exponential sine wave
     hsin                         ..F.A.... half of sine wave
     log                          ..F.A.... logarithmic
     ipar                         ..F.A.... inverted parabola
     qua                          ..F.A.... quadratic
     cub                          ..F.A.... cubic
     squ                          ..F.A.... square root
     cbr                          ..F.A.... cubic root
     par                          ..F.A.... parabola
     exp                          ..F.A.... exponential
     iqsin                        ..F.A.... inverted quarter of sine wave
     ihsin                        ..F.A.... inverted half of sine wave
     dese                         ..F.A.... double-exponential seat
     desi                         ..F.A.... double-exponential sigmoid
     losi                         ..F.A.... logistic sigmoid
     nofade                       ..F.A.... no fade; keep audio as-is
  curve2            <int>        ..F.A.... set fade curve type for 2nd stream (from 0 to 17) (default tri)
     tri                          ..F.A.... linear slope
     qsin                         ..F.A.... quarter of sine wave
     esin                         ..F.A.... exponential sine wave
     hsin                         ..F.A.... half of sine wave
     log                          ..F.A.... logarithmic
     ipar                         ..F.A.... inverted parabola
     qua                          ..F.A.... quadratic
     cub                          ..F.A.... cubic
     squ                          ..F.A.... square root
     cbr                          ..F.A.... cubic root
     par                          ..F.A.... parabola
     exp                          ..F.A.... exponential
     iqsin                        ..F.A.... inverted quarter of sine wave
     ihsin                        ..F.A.... inverted half of sine wave
     dese                         ..F.A.... double-exponential seat
     desi                         ..F.A.... double-exponential sigmoid
     losi                         ..F.A.... logistic sigmoid
     nofade                       ..F.A.... no fade; keep audio as-is
  c2                <int>        ..F.A.... set fade curve type for 2nd stream (from 0 to 17) (default tri)
     tri                          ..F.A.... linear slope
     qsin                         ..F.A.... quarter of sine wave
     esin                         ..F.A.... exponential sine wave
     hsin                         ..F.A.... half of sine wave
     log                          ..F.A.... logarithmic
     ipar                         ..F.A.... inverted parabola
     qua                          ..F.A.... quadratic
     cub                          ..F.A.... cubic
     squ                          ..F.A.... square root
     cbr                          ..F.A.... cubic root
     par                          ..F.A.... parabola
     exp                          ..F.A.... exponential
     iqsin                        ..F.A.... inverted quarter of sine wave
     ihsin                        ..F.A.... inverted half of sine wave
     dese                         ..F.A.... double-exponential seat
     desi                         ..F.A.... double-exponential sigmoid
     losi                         ..F.A.... logistic sigmoid
     nofade                       ..F.A.... no fade; keep audio as-is


