Welcome to Doom9's Forum, THE in-place to be for everyone interested in DVD conversion.

Before you start posting please read the forum rules. By posting to this forum you agree to abide by the rules.

 

Go Back   Doom9's Forum > Capturing and Editing Video > Avisynth Usage

Reply
 
Thread Tools Search this Thread Display Modes
Old 31st October 2016, 20:20   #1  |  Link
bilditup1
Registered User
 
bilditup1's Avatar
 
Join Date: Feb 2004
Location: NYC
Posts: 123
Is this fixable? ("Field blending"?)

Trying now to process my Tintin DVDs, and dealing with a trouble spot in the first ep. This is not regular combing, it's something else, some kind of weird intermittent aliasing effect on edges (pay attention to windows and window sill in upper-left quadrant). Possibly field-blending? - but this is a mostly 23.976fps source that was produced that way in Canada, and I thought this was more of an issue related to conversion to and from 25fps. Going through the video, the windows and window sills appear to look fine in combed frames but rubbish in the otherwise good ones. Can somebody please explain what's happening here and if this is something that could be dealt with? Thanks.

Excerpt link
bilditup1 is offline   Reply With Quote
Old 3rd November 2016, 18:12   #2  |  Link
LemMotlow
Registered User
 
Join Date: Jul 2011
Location: Tennessee, USA
Posts: 266
There is no field blending. It uses pulldown on 1 frame every 5 frames to get 29.97fps from film speed animation created at 12fps. You can get 23.976 fps progressive by using inverse telecine (TIVTC), then use sRestore to get the original 12fps video with no duplicate frames. Anyway, that's the way it looks to me. What happened with all the aliasing in the background diagonals near the end of the clip is anyone's guess.

Code:
MPEG2Source("path...........\goons.d2v")
AssumeTFF()
TFM(pp=0).TDecimate(cycle=5,cycleR=1)
sRestore(frate=12)
goons_12.mp4 sample @12fps download (2.3 MB): https://www.mediafire.com/?v0n2eaadqeei926

Last edited by LemMotlow; 3rd November 2016 at 22:52.
LemMotlow is offline   Reply With Quote
Old 4th November 2016, 01:22   #3  |  Link
poisondeathray
Registered User
 
Join Date: Sep 2007
Posts: 3,982
Quote:
Originally Posted by LemMotlow View Post
There is no field blending. It uses pulldown on 1 frame every 5 frames to get 29.97fps from film speed animation created at 12fps. You can get 23.976 fps progressive by using inverse telecine (TIVTC), then use sRestore to get the original 12fps video with no duplicate frames. Anyway, that's the way it looks to me. What happened with all the aliasing in the background diagonals near the end of the clip is anyone's guess.

Code:
MPEG2Source("path...........\goons.d2v")
AssumeTFF()
TFM(pp=0).TDecimate(cycle=5,cycleR=1)
sRestore(frate=12)
goons_12.mp4 sample @12fps download (2.3 MB): https://www.mediafire.com/?v0n2eaadqeei926
The first part is 12fps content, but I'd be careful because the section of interest has more than 12fps content /motion . You'd be throwing away motion samples in that section. I'd guess that there are others sections in the actual dvd that are more than 12 fps content







Quote:
Originally Posted by bilditup1 View Post
Trying now to process my Tintin DVDs, and dealing with a trouble spot in the first ep. This is not regular combing, it's something else, some kind of weird intermittent aliasing effect on edges (pay attention to windows and window sill in upper-left quadrant). Possibly field-blending? - but this is a mostly 23.976fps source that was produced that way in Canada, and I thought this was more of an issue related to conversion to and from 25fps. Going through the video, the windows and window sills appear to look fine in combed frames but rubbish in the otherwise good ones. Can somebody please explain what's happening here and if this is something that could be dealt with? Thanks.

The aliasing at the 4-5 second mark looks like parts of it had been deinterlaced at some point. As to why are only some frames were mishandled in that affected section, I don't know but somebody somewhere goofed up.

There is no "easy" fix that is "good"

Is this the only scene affected on the disc ?

One way is to use strong antialiasing filters , something like QTGMC in progressive mode (input type =1 or 2) or even stacking a few , to stabilize the BG, but that will cause lots of motion artifacts on foreground objects

Another approach is to do some manual work with rotoscoping/masks. Since the background is mostly static, and there are a few good frames to take parts from - you can try to make a BG clean plate +/- some antialiasing for foreground objects and composite them . So if it's more than a few scenes it's going to be a lot of work
poisondeathray is offline   Reply With Quote
Old 4th November 2016, 03:14   #4  |  Link
LemMotlow
Registered User
 
Join Date: Jul 2011
Location: Tennessee, USA
Posts: 266
Quote:
Originally Posted by poisondeathray View Post
The first part is 12fps content, but I'd be careful because the section of interest has more than 12fps content /motion . You'd be throwing away motion samples in that section. I'd guess that there are others sections in the actual dvd that are more than 12 fps content
I suspect so myself, as there was already a 1-in-5 sequence break with the first shot of the dog and the frame before it. I broke it down to unique frames to look at that aliasing. It looks like bad deinterlace but it only affects the background objects and the car. So that's a new one on me. You see something new with reworked digital garbage every day.
LemMotlow is offline   Reply With Quote
Old 4th November 2016, 03:23   #5  |  Link
poisondeathray
Registered User
 
Join Date: Sep 2007
Posts: 3,982
Quote:
Originally Posted by LemMotlow View Post
I suspect so myself, as there was already a 1-in-5 sequence break with the first shot of the dog and the frame before it. I broke it down to unique frames to look at that aliasing. It looks like bad deinterlace but it only affects the background objects and the car. So that's a new one on me. You see something new with reworked digital garbage every day.

Look closely - on frames that are affected , foreground objects are affected too , the 2 guys, and the dog . The BG , car only appear to be affected "more" , because higher proportion of nearly horizontal lines. But the FG objects have stair stepping / broken lines too whenever the BG is affected

Anyways, IVTC + QTGMC(inputtype=2 , preset="very slow") is very damaging but stabilizes it somewhat. It can be combined with some rough roto to clean it up decently
poisondeathray is offline   Reply With Quote
Old 4th November 2016, 04:11   #6  |  Link
LemMotlow
Registered User
 
Join Date: Jul 2011
Location: Tennessee, USA
Posts: 266
There's definitely something haywire with those aliased segments. In the original pulldown version the top border flutters up and down on the same frames. The aliasing mostly affects lines at certain angles.
LemMotlow is offline   Reply With Quote
Old 8th November 2016, 20:45   #7  |  Link
bilditup1
Registered User
 
bilditup1's Avatar
 
Join Date: Feb 2004
Location: NYC
Posts: 123
Quote:
Originally Posted by poisondeathray View Post
Another approach is to do some manual work with rotoscoping/masks. Since the background is mostly static, and there are a few good frames to take parts from - you can try to make a BG clean plate +/- some antialiasing for foreground objects and composite them . So if it's more than a few scenes it's going to be a lot of work
Have you got a guide on how to rotoscope or make masks effectively?

Quote:
Originally Posted by poisondeathray View Post

Anyways, IVTC + QTGMC(inputtype=2 , preset="very slow") is very damaging but stabilizes it somewhat. It can be combined with some rough roto to clean it up decently
Aight, I'll keep that in mind. Thanks.
bilditup1 is offline   Reply With Quote
Old 8th November 2016, 20:46   #8  |  Link
bilditup1
Registered User
 
bilditup1's Avatar
 
Join Date: Feb 2004
Location: NYC
Posts: 123
Also, how can you guys tell that the content is 12fps at any given point? Thanks to both of you for chiming in.
bilditup1 is offline   Reply With Quote
Old 8th November 2016, 23:14   #9  |  Link
LemMotlow
Registered User
 
Join Date: Jul 2011
Location: Tennessee, USA
Posts: 266
Quote:
Originally Posted by bilditup1 View Post
Also, how can you guys tell that the content is 12fps at any given point? Thanks to both of you for chiming in.
If you remove telecine material and discard all of the duplicate frames you'll get 12fps. But it should be playing at 23.976 or 24fps as the maker intended, so removing telecine alone would be enough and would maintain natural motion.

If you had to do a lot of denoisiing, the duplicate frames would be a problem. But you could work around that by separating odd and even frames, then apply filters to each group, then interleave the separated frames together again.
LemMotlow is offline   Reply With Quote
Old 9th November 2016, 00:08   #10  |  Link
poisondeathray
Registered User
 
Join Date: Sep 2007
Posts: 3,982
Quote:
Originally Posted by bilditup1 View Post
Have you got a guide on how to rotoscope or make masks effectively?

It's a big topic to do rotoscoping for the type of accuracy you need in this scenario "properly" or "efficiently" . But the generate idea is you just draw a mask around objects and the mask animates, isolating the object of interest. This way you separate objects into layers which you can composite together. Typically, you would use something like after effects or mocha. There are many tutorials on youtube and similar sites, I don' t know of any good ones offhand. There are some "easy" tools like rotobrush in AE, which is semi automated but not as accurate - but it might be good enough for many cases. There are various tips and tricks that can make roto work go much faster. People tend to start out go frame by frame - that's not the way to do it. It's the most despised gruntwork in compositing and VFX work because it's can become very tedious even for dedicated roto artists with dedicated software and hardware.

There are many ways you can generate masks in general in avisynth, but it won't be accurate enough here for what you want to do, and since roto is the most time consuming, it's always the last resort




Quote:
Originally Posted by bilditup1 View Post
Also, how can you guys tell that the content is 12fps at any given point?


The correct way to determine the fps in general is examine the fields for unique motion. Or another way is to bob it to 59.94 to look at the unique frames (maybe with yadif(1,1) if top field first) . I wouldn't IVTC right away first, because you can lose motion samples - if there is a 29.97 fps section for example. It's very common in cartoons, some sections like the intro or credits have a higher content framerate . Or sometimes some sections or even 59.94 parts or sections like overlays
poisondeathray is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT +1. The time now is 04:52.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2019, vBulletin Solutions Inc.