[MPlayer-users] Re: [-] Re: [-] Crop before deinterlacing OK?

[Rich Felker]

On Sat, Jul 23, 2005 at 12:35:53AM +0200, Matthias Wieser wrote:
> Am Montag, 18. Juli 2005 15:03 schrieb Guillaume POIRIER:
> > Hi,
> >
> > On 7/8/05, RC <rcooley at spamcop.net> wrote:
> > > On Thu, 7 Jul 2005 10:34:40 +0200
> > >
> > > Matthias Wieser <mwieser at gmx.de> wrote:
> > > > Less work for the deinterlacing filter.
> > >
> > > In most cases, it's a nominal difference.
> > >
> > > > I thought you only need to inverse teleine when capturing NTSC
> > > > movies. Normal NTSC TV broadcasts can be deinterlaced with pp=[md|
> > > > lb...], right?
> > >
> > > You'll find that NTSC broadcasts are commonly telecined, also. 
> > > Inverse telecine filters don't have negative side-effects if the
> > > content is not telecined, so it's best to always include it.
> >
> > I fought quite a bit against NTSC content for the past week. From my
> > perspective, even thought ivtc doesn't _harm_ strictly speaking when
> > the content is not telecined, putting it "blindly" is not what I'd
> > recommend.
> 
> What about those standard deinterlacers? I think about kerndeint or pp=md. 
> Motion would probably not be as smooth as with an inverse telecine filter 
> but would it be scceptable for a normal-quality TV recording?

Depends on whether you care or not. 30fps deinterlacers destroy the
content really bad, and look particularly bad with telecined content
since it will be both choppy and low-resolution afterwards. Your only
hope of good results with deinterlacing is to use a 60fps
deinterlacer, i.e. tfields.

> > That's because when you ivtc, you most of times change 
> > framerate back to mostly the original framerate of the movie. Now, if
> > you do not set the correct output framerate with "-ofps", you'll
> > either end-up with duplicate frames
> 
> How does it look like? I could imagine that those CNN live tickers would 
> show some unsteady motion if frames were duplicates. But does it matter 
> for movies?

Yes, especially during pans.

> > So please-please-please, identify your source before launching the
> > encoding process.
> 
> Hm, quite a challenge when doing timer based TV recording!

For live recording you should not do any processing, but keep it in
the original (interlaced) format. Then you can reencode later to
restore it to something watchable.

> But let's assume someone is recording a movie. Would detc be an good 
> option? The manpage says that ivtc does not like noisy input.

It really depends on how bad your TV signal is. Cable (with a good
connection) or satellite should be fine. Terrestrial analog broadcast
may be good or bad depending on the user's antenna system and the
proximity to the station.

> What would be an good option for the daily soap opera? ivtc together with 
> -ofps 30000/1001, or better detc (any advice for the sub-options?) with 
> -ofps 30000/1001?

No, soaps are not telecined as far as I know; they're low budget video
productions. And you should never use -ofps 30000/1001 with inverse
telecine, except perhaps in the case where you're using pullup and the
original is mixed 24p and 30p (30p is VERY RARE THOUGH! ONLY FOUND IN
SOME ANIME AND CG MOVIES!).

Rich