[MEncoder-users] about filmdint/pullup

[Peter Cordes]

On Mon, Jul 30, 2007 at 12:09:09AM +0100, vdmsss wrote:
> Thanks Peter. See below.
> 
> On 29 Jul 2007, at 22:44, Peter Cordes wrote:
> > vdmsss wrote:
> >> Hello. I have been playing with filmdint. My main source are films
> >> broadcast on DVB at 50i, and since most tutorials and discussions
> >> around are based on NTSC, and I am left with some doubts:
> >
> >>       Can filmdint (or pullup) be used to convert from 50i to 24p?
> >
> >  The only reason you want to convert FPS is so it matches  
> > tutorials?  Don't
> > do that.  PAL is usually much easier, because it's almost never  
> > telecined,
> > just sped up, so you can just skip the parts of tutorials that deal  
> > with
> > maybe needing to inverse telecine.
> 
> The reasons I want to this is to encode movies with the original  
> frames (as much as possible), and secondarily to learn to use  
> filmdint/pullup and other advanced features of mencoder.

 These goals are probably mutually exclusive, since AFAIK most movies are
converted to PAL by simply increasing the framerate (so film frames match up
1:1 with PAL frames) and speeding up the audio (but processing it to keep
the pitch constant).  I'm assuming when you say "original frames", you mean
not dropping anything from the original film, not original frame rate.  If
so, I don't see how you have anything to gain from slowing the movie down to
24fps, unless you're really picky about time.  I don't find that PAL movies
look like things move to fast ("Hey, that looks like gravity=10.2m/s^2,
what's up with that...")

 The only problem that can happen is that it is captured with the wrong
field first, so you have 1b:2a 2b:3a 3b:4a ...  where numbers are film
frames, a/b are first/second field of the frame.  If your videos look
combed, then have a look at the help in the man page for -vf phase.  You are
unlikely to need any inverse telecine, luckily for you.  If they don't look
combed at all, then you don't need to do anything.

> The point is that, as I said, most of my sources are from DVB-T, and  
> sometimes it can be tricky to understand what needs to be  
> deinterlaced and what can be left unchanged. Do you know of any tools  
> on MacOSX (or indeed mencoder demuxer option) that would allow me to  
> inspect fields and their flags? (I often use Project X to demux, but  
> it doesn't give much info on the streams, and what it gives is not  
> always documented...)

 mplayer prints messages about switching to 24000/1001 progressive and back
when playing NTSC dvds that have soft telecined content.  I don't think I've
ever found anything really good for inspecting MPEG streams.

-- 
#define X(x,y) x##y
Peter Cordes ;  e-mail: X(peter at cor , des.ca)

"The gods confound the man who first found out how to distinguish the hours!
 Confound him, too, who in this place set up a sundial, to cut and hack
 my day so wretchedly into small pieces!" -- Plautus, 200 BC