Filter spectrumsynth
  Convert input spectrum videos to audio output.
    Inputs:
       #0: magnitude (video)
       #1: phase (video)
    Outputs:
       #0: default (audio)
spectrumsynth AVOptions:
  sample_rate       <int>        ..F.A.... set sample rate (from 15 to INT_MAX) (default 44100)
  channels          <int>        ..F.A.... set channels (from 1 to 8) (default 1)
  scale             <int>        ..FV..... set input amplitude scale (from 0 to 1) (default log)
     lin             0            ..FV..... linear
     log             1            ..FV..... logarithmic
  slide             <int>        ..FV..... set input sliding mode (from 0 to 3) (default fullframe)
     replace         0            ..FV..... consume old columns with new
     scroll          1            ..FV..... consume only most right column
     fullframe       2            ..FV..... consume full frames
     rscroll         3            ..FV..... consume only most left column
  win_func          <int>        ..F.A.... set window function (from 0 to 19) (default rect)
     rect            0            ..F.A.... Rectangular
     bartlett        4            ..F.A.... Bartlett
     hann            1            ..F.A.... Hann
     hanning         1            ..F.A.... Hanning
     hamming         2            ..F.A.... Hamming
     sine            9            ..F.A.... Sine
  overlap           <float>      ..F.A.... set window overlap (from 0 to 1) (default 1)
  orientation       <int>        ..FV..... set orientation (from 0 to 1) (default vertical)
     vertical        0            ..FV.....
     horizontal      1            ..FV.....


