Bob deinterlacing is throwing frames out of order...?

[CaseyStelken]

I've been applying what I've learned thus far about capturing and encoding/filtering to some crappy old childhood VHS tapes before I start capturing and filtering my more important stuff, just to make sure I feel confident about what I'm doing so far.

The following is a short snippet from an old Baby Huey VHS, captured in VirtualDub from a JVC HR-S7900U VCR through a GV-USB2 capture cable:
Huey test [selection].avi

(First off - does that look okay? I mean, I know it's a crappy old tape made from a crappy old master... but does anything appear obviously wrong with my capture?) [Note: the audio is muted intentionally to spare you from hearing his moronic voice.]

Next is the same snippet, encoded through Hybrid. I cropped the video and corrected the aspect ratio, deinterlaced the fields, and applied the BOB effect:
Huey test [selection - cropped, deinterlaced, bob].mp4

You'll notice in the "Bobbed" version that a few frames seem to occasionally get mixed up... most obviously when Huey swings his arm down to snatch the diploma at around the 4.5-second mark.

Any idea on what causes this to happen? Any advice?

My top guesses are:

A. I did something wrong somewhere.
B. It's just a common, occasional side effect of Bobbing any deinterlaced footage.
C. Since traditional cel animation isn't always captured at 24fps, Bobbing it can sometimes result in unexpected issues like this.

(Side note - I'm guessing it's pointless to apply the Bob effect to captured animation or major motion pictures, because it's rarely ever filmed at more than 24fps... is that correct? Would it only be beneficial to "Bob" VHS footage of things like local news, sports, or soap operas? Or perhaps I'm misunderstanding something there.)

Any feedback about this particular issue (or about my process at all) is much appreciated! Thanks!

P.S. Almost forgot - here are the settings I used for deinterlacing, if it means anything to anyone:
Huey settings 01.jpg

[Aya_Rei]

The reason is simple, you are not suppose to deinterlace this type of footage (animation, footage from movies, pretty much footage that was filmed at 24 frames per second), but instead use inverse telecine. Unless the 24fps footage is mixed in with 29.97 footage, if it's mixed then there is nothing to do but deinterlace

Change auto deinterlace handling to TIVTC, just in case I also change the overwrite input scan to telecine.

Here's what it looks like with inverse telecine, all I did was that, cropping and a small bit of denoising.
Casey_BabyHueyTest.mp4

Looking at the footage itself, it seems fine enough. Sure it's noises and there are some rainbow sploches, but I'm assuming with how soft it is, is that the tape was recorded in EP mode? There are also frames where there is some slight jittering, that can be corrected by using this manual script (You have to find the offending frames manually, ain't fun)

[CaseyStelken]

Quote:

Originally Posted by Aya_Rei

The reason is simple, you are not suppose to deinterlace this type of footage (animation, footage from movies, pretty much footage that was filmed at 24 frames per second), but instead use inverse telecine.

Oh wow! That's not at all the answer I was expecting! What a misunderstanding on my part... here for the past few months as I've been learning about all this stuff, I had it backwards - I thought deinterlacing was used for pretty much any VHS captures, but detelecine was used for certain television broadcasts (news, soaps, etc). After seeing your comment and doing some more learning about the telecine process, I see that I had it backwards. Thanks for that bucket of knowledge! I sure appreciate it. Glad I got that straightened out before I did too much work on my tapes... This makes me feel really good about my decision to do some test runs before diving in too deep, haha.

Quote:

Originally Posted by Aya_Rei

Change auto deinterlace handling to TIVTC, just in case I also change the overwrite input scan to telecine.

So, under the (De-)Interlace/Telecine tab, I changed the Auto deinterlace handling dropdown to "TIVTC (Vapoursynth)," and changed "Overwrite input scan type" to "telecine" as you advised (thank you!). But I'm kinda lost with what to do with a lot of the other options on that screen...

Any chance you could show me a screenshot of what settings you used on that tab, or give me any advice on what some of these settings mean, or which settings you've found most useful?


Side note - Here's something that popped into my head as I've been wrapping my mind around all this... what about animated programs made specifically for television, but later released on VHS? Say, for example, the original 1980's He-Man series? I assume it was still created at the industry standard of 24fps and then telecined for television... but are there any cases where animated television shows were created at 29.97 fps to specifically fit the NTSC broadcast television standard? Or is that never really worth considering when capturing tapes? Hopefully the way I'm wording that makes sense, and I'm guessing the answer is "no, that never happened..." but if I don't ask, it'll always be in the back of my mind when I'm capturing and encoding certain animated programs, haha.

[Aya_Rei]

When it comes to the TIVTC settings, I just leave that at default and to me, that does the trick.

Your assumption is incorrect in a way, inverse telecine depends on the source of the footage, for example, 2D animation and films are meant to be inverse telecined back to their original frame rate of 24 FPS, if you try to deinterlace that type of footage you'll see duplicated frames. But news broadcasts and some sitcoms were shot at 29.97 FPS, so they must be deinterlaced.

An easy way to check is to load the footage into VirtualDub and add a deinterlace filter, look frame by frame to see if any frames repeat themselves. Now when it comes to tapes that have a mix of sources, as in some of it is 24 FPS and other parts are 29.97, then the only thing you can do is deinterlace. An example being that Japanese Terminator 2 clip you gave us, deinterlaced it because of the Japanese special effects being animated at 29.97

I might be wrong but I think even animated shows had the 3:2 pull down applied to fit onto tape, so they must be de telecined, unless the footage is mixed in with 29.97 sources, like it's used in a documentary or commercial.

[traal]

I see a vertical jitter every 20 frames in the source almost like clockwork which is strange.

Anyway, I've seen the back and frame order issue during deinterlace when the field order is wrong, but neither AssumeTFF() nor AssumeBFF() fixes it this time. I wonder if it's periodically switching field order. That would indicate a problem on the source tape that might show up even on a CRT.

Here's a similar discussion: https://www.digitalfaq.com/forum/vid...order-fix.html

IVTC never works perfectly for me even with DVDs and so I just use QTGMC instead.