Is There a Stronger Deinterlacer than Decomb?

kaitoujuliet · Post by **kaitoujuliet** » Tue Dec 10, 2002 9:03 pm

I've been playing around with some footage lately, and it seems to be full of ghosts even though I'm running it through the Decomb filter. Here are the details...

Footage ripped from Urusei Yatsura vol. 3 and Oh My Goddess vol. 2 DVDs, using DVD Decryptor

Saved as a DVD2AVI project using no special (non-default) settings

I have the AMVapp pack installed, although I got a message that Lame didn't install properly and I haven't re-installed it yet

AviSynth script reads as follows:
LoadPlugIn("c:\video\Decomb\Decomb.dll")
mpeg2source("[path to file]")
Telecide()
Decimate(5)

Ghosts seen through both VirtualDub and Premiere 5.1

When I tried running the script without Decomb, the "ghosts" became much more pronounced, i.e. I could tell I was looking at totally interlaced footage.

Any suggestions?

trythil · Post by **trythil** » Tue Dec 10, 2002 10:07 pm

Well, the "strongest" de-interlacing is to simply delete either the even or odd fields. This, of course, makes video look really, really bad, especially if you have lots of sharp diagonal/curved edges (the likes of which happen all the time in anime).

You may want to try different Telecide parameters, like decreasing the threshold parameter, or playing around with the reverse or chroma flags.

ErMaC · Post by **ErMaC** » Tue Dec 10, 2002 10:11 pm

Decomb is not a deinterlacer - it's an Inverse Telecine plugin. It can also do plain old deinterlacing (via FieldDeinterlace) but Telecide+Decimate is IVTC, not plain old deinterlacing.

Try SmoothDeinterlace, as the guides mention.

jbone · Post by **jbone** » Tue Dec 10, 2002 11:33 pm

Trust Decomb MAXX(TM) for all those REALLY TOUGH deinterlacing problems!

kaitoujuliet · Post by **kaitoujuliet** » Wed Dec 11, 2002 9:52 am

ErMaC wrote:Decomb is not a deinterlacer - it's an Inverse Telecine plugin. It can also do plain old deinterlacing (via FieldDeinterlace) but Telecide+Decimate is IVTC, not plain old deinterlacing.

Whoops, sorry. I tend to use the terms interchangeably, but I guess they're not really the same. So if I'm running IVTC and still getting ghosts, do I need to run Deinterlace too?

ErMaC wrote:Try SmoothDeinterlace, as the guides mention.

I did check the guide before posting (love the new expanded one, by the way!), but I must have missed the section on SmoothDeinterlace. However, I just tried it and the ghosts actually got worse.

Would screenshots help? I've never made one before, but I think I know how.

Juliet

trythil · Post by **trythil** » Wed Dec 11, 2002 10:06 am

kaitoujuliet wrote:
ErMaC wrote:Decomb is not a deinterlacer - it's an Inverse Telecine plugin. It can also do plain old deinterlacing (via FieldDeinterlace) but Telecide+Decimate is IVTC, not plain old deinterlacing.
Whoops, sorry. I tend to use the terms interchangeably, but I guess they're not really the same. So if I'm running IVTC and still getting ghosts, do I need to run Deinterlace too?

Are you working with "real" interlaced material? The Telecide filter will only work to recover progressive frames from a telecined progressive source. (This is the reason why Donald Graft calls the filter "Decomb" and not "Deinterlace".)

If you are, you'll have to use a deinterlacing filter on the source material.

It's still possible, however, that you may just need to play with some parameters on the Telecide filter -- it may just be letting a lot of frames slip by.

Screenshots may help some people out (not me; I can't tell the difference between interlacing and telecining artifacts).

trythil · Post by **trythil** » Wed Dec 11, 2002 10:19 am

kaitoujuliet wrote:I did check the guide before posting (love the new expanded one, by the way!), but I must have missed the section on SmoothDeinterlace. However, I just tried it and the ghosts actually got worse.

One other thing (I need to learn how to read posts):

Because simple deletion and duplication of fields looks so bad, most deinterlacers will not merely duplicate fields but try to interpolate (read: bullshit) field data from either two concurrent even or two odd fields, depending on which field it's trying to reconstruct. This blending process will not eliminate ghosting artifacts; in fact, it'll create them. But you won't get scanlines.

RadicalEd0 · Post by **RadicalEd0** » Wed Dec 11, 2002 10:27 am

k, ghosting is usually a product of blend deinterlacing. That is, since an interlaced frame is really 2 frames in one (2 points in time displayed in the same frame), and blend deinterlacing blurs these points or fields together, a mixed image of the past point and the point 1/60th of a second away from it is created.

during telecine progressive pictures are split into two fields and then weaved with other fields to create pseudo extra frames.
inverse telecine, what decomb does, takes the 2 points out of the single frame and combines them with their proper original other field restoring the progressive pictures. This makes for no ghosting (unless interlaced frames sneak through and are fielddeinterlaced)

the only way to deinterlace without ghosting is to use separatefields() with selecteven() in avisynth, which splits the 2 fields into 2 separate half-frames and then deletes every other frame. smoothdeinterlace will do the sort of thing described first (blend deinterlace).

RadicalEd0 · Post by **RadicalEd0** » Wed Dec 11, 2002 10:28 am

posting at the same time as trythil

mckeed · Post by **mckeed** » Wed Dec 11, 2002 11:59 am

from actually trying what you were doing wit the ahh my goddess DVD's for a previous video project, I can tell you that its a pain in the ass to try to de-interlace those things.....they were mastered in NTSC which means that they are interlaced on the DVD to begin with and there aren't any tags on the fileds to put them back into 23fps. For that DVD you won't really be able to clean them up all that much. But if you make the cuts right you should be able to get around it. I know that is what I did.....that and manual deinterlacing with stills with the frame I wanted inserted into the right place. If you do get them decently de-interlaced though....i would be interested in knowing how you did it. i know i tried for a long time to do this and couldn't get a result I was happy with.