[MEncoder-users] Trouble transcoding 1080i "video" to NTSC DVD

Walter Belhaven wbelhaven at yahoo.com
Thu Mar 9 07:21:35 CET 2006


I'm having trouble transcoding 1080i HD "video" (interlaced) content
from my Tivo HR10-250 to "standard" NTSC DVD.  The video source is a
live hockey game.  The goal (heh-heh) is to burn a DVD-R that will
play on a "standard" set top DVD player.  After reading, re-reading,
ad nauseum, the mencoder manual, I'm getting close, but I'm not quite
there yet.

With scale:w:h:1, ildct, and ilme, I've been able to preserve the
"video" appearance of the original and get very smooth motion on the
transcoded output.  That's the good news.  But I still can't get past
the following two problems:

1. The original HD source changes field-order every period!  The 1st
and 3rd periods are Bottom-field first, and the 2nd period and
post-game wrap-up are Top-field first.  This is according to DGIndex
on the original .ty file, and it's absolutely the case that the
transcoded video goes from sweetness in the 1st and 3rd periods, to an
unwatchable mess in the 2nd.  I've tried all possible permutations of
the 'phase' filter to fix the field order, but none of them seem to
work.  Perhaps I've got the filter in the wrong place in the pipeline
though (see example below).

2. I still get freezes and stutters in my two set-top players, a
Panasonic and a Sony, even though the DVD-RW plays fine in the
computer.  Note: every DVD-R/RW I've burned with this same burner, on
source that was derived from a "real" DVD via DVD Decrypter/Shrink has
played perfectly, with no freezes nor stutters, on those same set-top
players.  Therefore, I suspect there's something wrong with my
transcoded MPEG file, as opposed to there being a "media" problem.

Item 1, while annoying, I can work around by splitting the original
into several files and transcoding them separately, manually reversing
the field order when necessary.

Item 2, though, is a show-stopper.  Can anyone offer any hints, tips,
or tricks on how to fix this?

Here's the most promising command line I've devised to date.  Note
that I haven't bothered with any of the "high quality" transcoding
switches while in this "debug" phase; i.e., I just want something that
works, and the video quality is quite excellent even in this "low
quality" mode ... when it's not freezing, of course:

mencoder -delay 0.3 -oac copy -ovc lavc -of mpeg -mpegopts \
  format=dvd -vf phase,crop=1264:1072,scale=720:480:1,harddup \
  -lavcopts vcodec=mpeg2video:vrc_buf_size=1835:vrc_maxrate=9696: \
   vbitrate=5731:keyint=18:aspect=16/9:ildct:ilme \
  -ofps 30000/1001 -o output.mpg input.mpg

Thanks for any and all help, and thanks to the authors of these
amazing programs.


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