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

Steven Adeff adeffs.mythtv at gmail.com
Mon Feb 13 23:33:56 CET 2006

On 2/12/06, pfile at pacbell.net <pfile at pacbell.net> wrote:
> > 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 have noticed this too. what eventually ends up coming over the air
> has been transcoded up the wazoo and overlayed at 60fps, etc. etc.
> >
> > 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...
> >
> i've never looked at WB, but i'm not surprised based on what i know
> about D*. D* really has some aggressive mpeg. for 29.97 content they
> usually only broadcast 2 fields for every 3, and use the RFF flag. also
> they keep alternating between BFF and TFF. this seems to confuse the
> mplayer/mencoder mpeg demuxer when the content was telecined 24fps - it
> keeps switching framerates. however, i've found that just forcing
> mencoder to treat the framerate as 30000/1001 and then using pullup,
> the right thing seems to happen. having said that, the nice thing is
> that on some of the movie channels, they send straight "progressive"
> interlaced 24fps material just like a DVD.
> so following up again, i happened to try the tinterlace,pullup,softskip
> chain on the finale of AD. this was one huge file with 4 eps in it;
> most of the file was fine but there were a few places where pullup had
> turfed the wrong frames. this is on a pre-edited TS file, so its
> possible that something got hosed up due to native 60fps commercials.
> also i am not necessarily running the latest version of mencoder (i
> think i'm on pre7) so i'll try with CVS and see if that's any better. i
> guess the tinterlace thing is a hack anyway so we're outside of the
> norm for what pullup is supposed to handle?
> as an alternative to pullup, i tried the decimate parameters you gave
> and something really went wrong. pretty much the whole file had the
> wrong frames skipped, and based on the log, decimate was not dropping
> anything. was it supposed to be 2:1000:1600:.001? or should min and max
> be swapped? i just noticed that my script was calling a pretty downrev
> version of mencoder, so i'll try again now with something more recent.
> rob

-vf decimate=2:1000:1600:.001 -ofps 24000/1001

I use pre7 currently


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