[MPlayer-users] Re: 60p -> 24p conversion for ATSC

[Steven Adeff]

On 2/10/06, rob <pfile at pacbell.net> wrote:
> RC <rcooley <at> spamcop.net> writes:
>
> >
> > Not much to describe.  All the ivtc filters work on fields, not frames,
> > so you put tinterlace before pullup/filmdint/ivtc/detc to give it fields
> > to work with.
> >
> > It only took a minute to find the original thread:
> > http://thread.gmane.org/gmane.comp.video.mencoder.user/536
> >
>
> ah! geez. clearly i am an idiot. i didnt realize there was an
> mencoder-users list; my google-fu was failing completely because
> i kept searching for mplayer-users plus other stuff.
>
> the OP in that thread seems to think this technique does not work, but
> it seems to me that it should. i'm trying it out right now. i'm
> occasionally seeing skipped frames and duplicated frames, but this
> may be during commercials. i'll have to try and correlate the bursts
> of problem areas with the comms.
>
> Steven Adeff <adeffs.mythtv <at> gmail.com> writes:
>
> > -vf decimate=2:1000:1600:.001,
> > has worked great for me on all my 60p HDTV content to bring it back
> > down to 24p.
> > I've never found an instance where "those windows programs" get it
> > right where this doesn't, and I've encoded a lot of 60p content.
>
> in fact this is what i had been doing, but i hadnt yet found the magic
> min/max/frac values yet, and as i mentioned in my original post, i was
> dropping too many frames in low-motion scenes... i guess i'll also try
> these arguments and see how it works out.
>

give it a whirl. I found a couple instances where it wasn't perfect,
but upon downloading some of the other release groups version found
that they're filter chain came up witht he exact same output as far as
which frames it decided to keep. It's never been worse than 2 frames
in 5 and never occurs "back to back", so I haven't bothered to try and
do better. The few times I noticed it occuring (during frame by frame
examination) was during the "Presented in HD" overlays used at the
beginning of a show, the animation for the overlay is never on the
same timing as the video (as though the video were driven to 60p then
the overlay added afterwards with no though as to the video), which
ends up screwing up the filter.

I've also noticed that the WB does some real strange frame timings
that require manual intervention. This doesn't occur for all WB
stations, but for the one I get OTA it does. The frame sequence will
change with every repeat so no amount of settings seem to catch each
change, especially when the length of the sequence changes...

--
Steve