Decoder cc_dec [Closed Caption (EIA-608 / CEA-708)]:
    General capabilities: delay 
Closed caption Decoder AVOptions:
  -real_time         <boolean>    .D...S.... emit subtitle events as they are decoded for real-time display (default false)
  -data_field        <int>        .D...S.... select data field (from -1 to 1) (default auto)
     auto            -1           .D...S.... pick first one that appears
     first           0            .D...S....
     second          1            .D...S....


