[mythtv-users] Speaking of transocding: 1080i deinterlace?

[Brad Templeton]

On Fri, Feb 13, 2009 at 04:29:19PM -0500, Steven Adeff wrote:
> On Fri, Feb 13, 2009 at 4:22 PM, Brad Templeton
> <brad+myth at templetons.com> wrote:
> > On Fri, Feb 13, 2009 at 01:14:04PM -0800, David Brodbeck wrote:
> >> On Fri, February 13, 2009 1:05 pm, Brad Templeton wrote:
> >> > c) Reduce the resolution to 1280x540 or even 1080x540, giving
> >> >             up half the lines and of course deinterlacing.
> >> >
> >> >         Do we use a different filter than above?  Perhaps "onefield"
> >> >         is simpler or is it better to stick with kerndeint or
> >> >         linearblend?
> >>
> >> I haven't tried it, but assuming the goal is to avoid comb artifacts, I'd
> >> use onefield for that.  It'd be much faster, and deinterlacing filters
> >> almost always cause some loss of sharpness, so I avoid using them when
> >> possible.
> >
> > Well, obviously downrezzing from 1080 lines to 720 or less will cause
> > loss of sharpness, I don't see the deinterlace filter adding more.
> > Presumably onefield gives you a 30 fps progressive result.   Do
> > the other filters also give a 30fps result or do they generate a 60fps
> > result, or does only bob (which is the best playback filter) do that?
> >
> > But I am interested to hear what people have tried.   In particular,
> > is it correct that interlaced dct encoding and mostion estimation are
> > only for interlaced video (and presumably they do nothing on progresive
> > video or even more ideally would not be applied by mythtranscode).
> > If you are deinterlacing first, you would not use them, right?
> 
> the doom9.org forums are *the* place to go to learn about all this
> stuff.  from memory, motion estimation has nothing to do with
> progressive/interlaced, as well, dct encoding (though not the
> interlaced dependent version) can also be used for progressive video.
> What settings you use for both, and how much affect they have can be
> debated, but that is a better topic for the doom9.org forums =)
> 
> you can also take a look at the mencoder scripts I wrote a while back,
> they're on my mythtv wiki users page that's in my sig.
> 

I am familiar with the mechanics of transocding and deinterlacing
as would be talked about at doom9.    What I am asking about is what
people have found as the best specific flags for mythtranscode.  I
know how to do it with mencoder.

For example, I found that when I run mythtranscode with kerndeint
as a custom filter, the output was still interlaced according to
mythtv's "Video scan" menu item on playback.   Is this the sort
of thing they discuss over at doom9?    Again, my interest is only
what specific settings people have used in mythtv to drive mythtranscode
to good success, not advice on how to transcode.