[MPlayer-users] Detecting interlacing

Derek derek at deluxedistributors.com
Tue Feb 21 17:37:14 CET 2006

On Tuesday 21 February 2006 08:39, Tony Houghton wrote:
> In <20060220215407.79bfb3ad.rcooley at spamcop.net>, RC wrote:
> > On Tue, 21 Feb 2006 00:01:48 +0000
> >
> > Tony Houghton <h at realh.co.uk> wrote:
> > > Is there a way to detect whether a video (in particular vdr
> > > recordings) is interlaced with something like mplayer -identify?
> >
> > Nope.  Doing it by-eye is easy enough.  I've been considering something
> > like a video filter that will only detect and report if a video is
> > interlaced/hard telecined/progressive, but I'm not sure it's even worth
> > the effort...
> I think it would be worth it, and to go even further and have a filter
> that can enable and disable deinterlacing on the fly. I'm writing a
> script for a HTPC application to optimise MPlayer's options depending on
> what it's playing. It would be nice for non tecchy users not to have to
> check the video first then adjust options manually.
> Currently the main thing the script does is check the video's aspect
> ratio and set monitoraspect accordingly because it's generally best for
> MPlayer to think that the TV's 4:3 when playing 4:3 videos. (a) Because
> TVs can potentially do hardware scaling with less loss of quality than
> video cards, and (b) because MPlayer's automatic setting will be wrong
> if, for example, it plays a TV recording which starts off with
> widescreen adverts while the main programme is 4:3.

I have been looking for something exactly as described here in my recent work.  
I am new to video encoding, and don't really know how to identify 
telecine/interlacing video just by looking at it.  I am trying to write a 
script that will automatically detect as much as possible to automate the 
encoding process for many movies, and so far that is the part that I think is 
messing up the quality of my encodes.  

If a video filter were to be made to do this, I would be interested in helping 
to test it.

Also, a somewhat related question, is there anywhere I can go to see how 
telecine/interlacing looks, so that I can learn to visually identify it?

Derek P.

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