Interlacing and artifacts

[InfoCynic]

I'm playing around with using XviD with interlacing on as a solution to encoding everyone's favorite poster boy for deinterlacing nightmares: Star Trek TNG (from the NTSC DVDs). Why? well, because I can, and with lots of hard drive space, storing all the eps on disk instead of digging up the DVD for the one I want (and really, all I need to see is "Shut up, Wesley" over and over again). And because it seems like someday we might get to the point where real-time deinterlacing works really well enough to watch things encoded like this, even without a TV.

But my problem is that whenever I encode with interlacing, it adds noise. See http://35.11.210.171/images/tng_xvid_interlaced-artifacts.rar (~750k, 3 bitmaps, line speed may be slow) containing unfiltered (except 6/6 horizontal crop) vob, unfiltered AVI, and resized AVI (I tried encoding at 320x480 to improve compressibility, but it didn't help).

It's not a whole not of noise, and it's not the interlacing itself, the pictures clearly show the difference. One thing I found was that when I did 2nd pass mod HQ and hinted ME, the noise was much much worse than when I did both passes H263 and no hinted ME. The avs for encoding contains a horizontal crop, and a soft bicubic resize to 320x480.

XviD build is Koepi's stable (XviD-04102002-1), settings are default except:
motion search 6
enable interlacing
min i-frame 2
quants 2/6, 2/12
alt curve off

Is this a solvable problem on my end, a bug in the codec, an unavoidable problem with interlacing? Any clues? :) Thanks!

[-h]

I fear this may be due to the frame-bias eliminating too many possible field candidates. That stinks.

I'll do a couple mid-to-high quant tests and amend CVS as necessary. Your streams aren't buggy, the encoder is just making a poor choice in the frame-or-field test.

-h

[-h]

Oh one other thing, I always thought TNG was shot on film, and that there is a 24fps stream waiting to be recovered?

-h

[Boardlord]

OMG I, the humble user will correct the "Kilted Yaksman", the coder genius! .:) :sly:
Sorry :)

I don't know where is that thread, but TNG episodes are hybrid, as our gifted Donald Graft observed. The computer animated scenes are 30fps ntsc interlaced, and the normal scenes are 24fps film.

[InfoCynic]

Re: TNG 24fps...

Wouldn't that be nice? I consider it like NP-Complete problems. No one can conclusively prove that a better solution doesn't exist, but years of research and countless man-hours trying suggest otherwise. :)

Near as anyone can tell, the Special Effects were done as 30fps NTSC, and are 30 FPS NTSC INTERLACED on the DVD. The 'Bridge scenes' with no FX are 24 fps FILM telecined normally. Hybrid deinterlacing (decomb telecide/decimate mode 1) with some strong smoothing has been suggested, as has a certain scene group's "superfilter" which no one really knows what it's doing, and it's still leaving some combing behind anyway (and being encoded into an inferior codec which shall remain nameless ;)).

[-h]

Ah I remember I did have it wrong, I wasn't sure why exactly.

I have dreams of making a super fun happy frame rate convertor some day that can convert a 30 or 60 or 41 or 147.1135 fps sequence into 24 via temporal decimation/interpolation, eliminating the blur and combing that telecining or frame-dropping/averaging creates. The theory's all there, it's just that no one's coded it for the general population yet.

Some day, some day..

-h