[MPlayer-users] how to recognize deinterlaced video?

[Hans-Carl Oberdalhoff]

2005/12/2, Dietmar Hofer <didi at a-t-s.at>:
> 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?

Sadly, in many cases only your eye can tell.

If a video is (really) interlaced, two fields are mixed into one
frame. For the player it looks absolutely as if it was an normal
(progressive) video, since both offer a sequence of frames to decode
and display, but nothing more.
Some (Anime-)Dvds contain information, like "I am progressive, but
tread me as if telecined". In this case Mplayer gives some short
information about this and then plays it progressively.

> 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?
Well....
If it is interlaced and has, say, 25 frames per second, then you can
read this as 50 fields per second. You can watch this with -vf
tfields.
Interlacing was used to "compress" fluid movement (50 pics per sec)
into 25 pics per second. You could say, movement is traded for
resolution. (As a field has only half the height of a frame)

It is the other way around for telecine. If you have ca. 30 frames per
second telecined video, you really have ca. 24 frames per second of
progressive video. In contrast to interlace, telecine can be
completely undone if you have proper sources (see -vf pullup or
filmdint).

Be aware, that both interlace and telecine look nearly identical to
the eye when viewed!

Hans-Carl