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From: Stuart Miller on 29 Oct 2007 14:30

<invader(a)nospamforme.com> wrote in message
news:fg41rb125o2(a)news3.newsguy.com...
>I have mythtv box, running FC4 and xine v0.99.4. I'm using it to play VOB
>dvd
> video files. I have this connected to a hitachi 42" 1080p LCD via the VGA
> output.
>
> If I burn the DVD and play it in my standalone sony DVD player, the DVDs
> look
> fine.
>
> However, when I play the videos on the mythtv box using Xine, I get some
> bizarre scanline artifacts. The problem is most noticable when there is
> fast
> motion and appears as brief flashes where I can see alternating scan
> lines. A
> good example would be a drummer playing the drums in a music video -- the
> drum sticks get a sort of on-off pattern when moved quickly.
>
> I think I understand how interlacing works, but what I don't understand is
> why the problem exists and is so darn annoying with the software DVD
> player,
> yet the sony player has no such problem. Some videos and movies are
> clearly
> much worse than others.
>

You can get a much more complete answer from one of the dvd newsgroups, but
here is the simple version.
Interlaced means that in the first pass, lines 1,3,5,7 etc are refreshed,
and in the second pass, 2,4,6,8 are refreshed.
Progressive means that lines are refreshed 1,2,3,4...
Broadcast TV is interlaced to give better tracking for motion. They have
traded resolution for rapid frame changes.When you freeze frame, you can see
how bad the resolution really is, yet it looks ok because it is moving.
Computer monitors are progressive scan, to give the detail needed when the
screen does not change that much frame to frame.
In the old days, 640x480 was progressive, but higher resolutions were
interlaced, and that produced a noticeable flicker on the screen.

As I understand it, modern video cards and monitors can not easily display
interlaced signals, so the video is 'de-interlaced'. Often this is done by
discarding the even (or odd) numbered scan lines. In effect, you are
discarding half of the video information.

The problem arises from a fusion of technologies which were never intended
to meet.

There may be a solution to this which I am not aware of. Again, check witht
he dvd newsgroups.


> I tried to enable software deinterlacing by toggling the 'D' key in Xine.
> Software deinterlacing eliminates the scanline artifacts, but instead I
> get
> severe motion blurring. Let's say for example if a person was running
> across
> the screen, their movement will appear blurred and/or jumpy.
>
> I've confirmed that at all times (with or without software deinterlacing)
> that CPU utilization on the box is less than 20%.
>
> -----------------------------------------------------------
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