[MPlayer-users] -vf ilpack

[Ville Saari]

On Sun, Mar 07, 2004 at 01:52:07PM -0500, D Richard Felker III wrote:

> In fact in some cases it might be optimal to encode interlaced frames
> without any of the interlaced features (e.g. if there's almost no motion)

True, but for such frames it wouldn't hurt if progressive chroma subsampling
is used too.

> > Several PAL DVD are encoded so that progressive film content was
> > converted to interlaced video, which was then encoded to DVD with
> > opposite field dominance so that every frame is like the interlaced
> > frames of telecined NTSC.
> 
> Uhg. Do you have any idea what this does to the quality/bitrate?? :(

If the mpeg encoding was done using the interlaced features, then the
quality loss doesn't seem to be too bad, but if it was encoded
progressively, the result is a total disaster. But in both cases it
is a pain in the ass when you want to watch it on progressive
computer monitor.

I had the same problem when I captured the original Star Wars Trilogy
from VHS tapes using my DV camcorder as a D/A converter (first an
analog copy from VHS tape to DV tape and then digital transfer to
computer over firewire). The DV device pairs the fields always bottom
first, but the actual field order of the film-to-video transfer had
been more or less random. It stays constant for a few tens of seconds
at most and then switches around. And at each phase change there is a
visible jerk in the video even when watched on truely interlaced display,
because one film frame is represented by one or three video fields
instead of two.

I have also witnessed at least one case where 24 fps film content was
converted to PAL using 3:2:2:2:2:2:2:2:2:2:2:2-pulldown! The result
is visible jerks with constant 2 Hz frequency. Looks particularly
terrible when the camera is panned.

> Applying the linear blend filter afterwards should clean it up enough
> to be watchable without hurting the video quality too much. It will
> halve the ghosting in each field and spread both ghosts out over both
> fields so you don't see combing.

Yes, but vertical resolution is always compromised if the video is
deinterlaced. At least until someone implements a motion compensating
deinterlecer to mplayer :-)

I personally prefer pp=md over the other deinterlacers. Those deinterlacers
that use both fields equally cause ghosting and those that "invent" one
of the fields and use the other as is cause stairstepping in diagonal
edges. The pp=md belongs to the latter class, but it avoids the
stairstepping in the static parts of the image.

In this particular case pp=md banishes one of the ghosts completely and
removes the combing from the other.

-- 
 Ville