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

[rob]

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.

Rich Felker <dalias <at> aerifal.cx> writes:

> The basic idea is:
> -vf tinterlace,pullup

> The above filter chain will leave you with incorrectly double-height
> video. You can scale back down afterwards. There are tricks using
> nearest-neighbor resampling with the scale filter to get the exact
> right behavior and compensate for the incorrect fake interlacing that
> tinterlace makes, but I wouldn't suggest trying such things unless you
> have a problem with the output, since you're likely to make it worse
> if you don't understand the repercussions.

yeah, i modified my script to add tinterlace and scale back down and made
some test clips, and they all looked okay. so i've launched a full 2-pass
transcode of an entire show. i'll burn the scaling bridge if/when i come
to it :)

thanks everyone for your help.

rob