Re: [Thoggen-devel] Interlacing artifacts?

[Tim <t....@ze...>]

On Sun, 2006-11-19 at 16:08 -0500, Stefan Monnier wrote:

Hi Stefan,

> - the resulting video seems to have a slightly jumpy behavior (slight jumps
>   about 3 times per second maybe (could be anywhere between 2 and 4Hz,
>   I guess), maybe an artifact of the player, but I tried with both totem and
>   xine with same results).  This is fairly minor, only noticeable if you
>   really pay attention.

Can't say I've heard of this before or noticed it myself. Two possible
reasons I can think of:

 - currently Thoggen's pipeline forces the framerate to 25fps. This is,
erm,
   suboptimal particularly for NTSC input (but necessary to keep things
in
   sync when the input changes framerate). Should probably do something
   smarter here and at least use the specified rate. Then there's always
the
   possibility that you're using a version of the 'videorate' plugin
that
   doesn't work entirely right (there should be a bunch of fixes in
   gst-plugins-base CVS, but I don't remember details).

 - a bug in theoraenc/oggmux/oggdemux/theoradec (I am not aware of
anything
   like this though)


> - more annoying is the fact that the interlacing of the original DVD data
>   turns into comb-like artifacts when objects move.

The deinterlacer used isn't very good (and in addition maybe not
configured optimally either, not sure). Maybe thoggen should just use
the 'ffdeinterlace' interlacer from gst-ffmpeg if it is available on the
system (looks much nicer in my experience).

In general, we don't really handle interlaced content decently yet in
GStreamer. This includes specifications on how to pass interlaced
content internally [0] and a decent deinterlacer [1]. In other words:
this will improve one day when this stuff gets fixed there.

 Cheers
  -Tim

[0] http://bugzilla.gnome.org/show_bug.cgi?id=163577
[1] http://bugzilla.gnome.org/show_bug.cgi?id=163578