[MPlayer-users] Re: mpeg's and inverse telecine question

[Steven Adeff]

a few general questions on mplayer's IvTc and filters

How does mplayer's ivtc for hard telecined mpeg's compare to other offerings?

Is it better to run the 3d noise filter before or after the ivtc ?

Thanks!
-Steven

On Sunday 12 October 2003 02:03 pm, you wrote:
> On Sun, Oct 12, 2003 at 01:05:20PM -0400, Steven Adeff wrote:
> > Rich thanks for the response. I'm actually interested in inverse
> > telecine. See, I extract shows from my Tivo and convert them to SVCD.
> > recently someone told me about the whole inverse telecine process and why
> > its good to do. The thing is the person is a windows user and so I don't
> > really have a way of using their method in linux. So I'm trying to gather
> > information on this.
> >
> > This person said that mpeg decoders all automatically convert a 23.97
> > stream to 29.97 and so you need a special program to convert it to AVI in
> > order to run an inverse telecine filter on it.
>
> This part definitely isn't true. Hardware players meant to play it on
> TV (settop DVD/SVCD player) will automatically convert it to 29.97
> fps, either by themselves (mpeg1) or using the header flags (mpeg2),
> but if you're playing the DVD/SVCD in a computer using mplayer or any
> other good software, it will leave 23.976 fps ("soft telecined") files
> alone, so that you get nice progressive frames without having to run
> any inverse telecine process. If you're using MPlayer, it will say
> "TELECINE detected, switching fps to 23.976" or something to that
> effect if it encounters soft telecine.
>
> On the other hand, if your mpeg2 was just recorded from broadcast TV,
> the video is already telecined ("hard telecine") and the only way to
> recover clean progressive video is with special inverse telecine
> software. Hard telecine can't be detected by a computer, because it's
> just a matter of what data is stored in the frames, not any special
> flags/headers. But you can in practice detect it by watching your file
> one frame at a time and observing if two out of ever five frames
> have "combing" artifacts (aka interlacing).
>
> So, about what this person told you... In summary, mpeg decoders do
> not automatically convert to 29.97. But anything that generates a
> signal that can be viewed on a television DOES convert to 29.97.
> Including the equipment the TV stations use to broadcast movies on TV.
> So therefore, if you capture a movie with a TiVo or bttv or whatever,
> you'll have to use inverse telecine.
>
> Rich