[MPlayer-users] how to recognize deinterlaced video?

[Dietmar Hofer]

I often use mplayer to get information about video files, since it prints to 
console such usefull stuff like pid's in TS-streams, bitrates...
But I couldn't figure out how to know if a video stream is interlaced or not. 
Can somebody please give me a hint about this?
I also wonder how in case of interlaced content the fps value is to 
interpreted: as whole frames per second (which strictly speaking would be 2 
frames in this case) or as half frames per second?