Filter hwmap
  Map hardware frames
    Inputs:
       #0: default (video)
    Outputs:
       #0: default (video)
hwmap AVOptions:
  mode              <flags>      ..FV..... Frame mapping mode (default read+write)
     read                         ..FV..... Mapping should be readable
     write                        ..FV..... Mapping should be writeable
     overwrite                    ..FV..... Mapping will always overwrite the entire frame
     direct                       ..FV..... Mapping should not involve any copying
  derive_device     <string>     ..FV..... Derive a new device of this type
  reverse           <int>        ..FV..... Map in reverse (create and allocate in the sink) (from 0 to 1) (default 0)


