U.S. CitiesCity-Data Forum Index
Go Back   City-Data Forum > General Forums > Science and Technology > Consumer Electronics
 [Register]
Please register to participate in our discussions with 2 million other members - it's free and quick! Some forums can only be seen by registered members. After you create your account, you'll be able to customize options and access all our 15,000 new posts/day with fewer ads.
View detailed profile (Advanced) or search
site with Google Custom Search

Search Forums  (Advanced)
 
Old 05-07-2017, 03:15 PM
 
2,494 posts, read 4,768,658 times
Reputation: 943

Advertisements

Sometimes when I see a video version of a film, the image is slightly wiggling or shifting left and right. You can only notice this in a scene where the camera is not moving. Then look at the left or right edge. You might see lines wiggling left and right.

I just noticed this on the DVD of the original release of Star Wars A New Hope. But the DVD of the Special Edition does not do this. I believe most dvds don't do this, but I have noticed it. I think it has to do with the transfer from film to video. I first noticed it in the scene where Obiwan turns off the tractor beam.
Reply With Quote Quick reply to this message

 
Old 05-07-2017, 04:47 PM
 
Location: Somewhere in northern Alabama
18,537 posts, read 55,453,855 times
Reputation: 32256
Movie film has a lot more technical aspects than most people know about. The transfer to video can suffer for a few reasons, and the film itself can have problems. George Lucas has been a film historian's nightmare in how shabbily he treated all aspects of the original Star Wars.

The first prints were a rush job. The reel with the cantina scene was shipped to my theatre with the image on the soundtrack strip and visa versa, requiring a fresh reel to be air freighted in. I never had anything like that happen before or since. On the soundtrack record, I had to return three pressings before I bought one that did not have major imperfections in the vinyl.

The side to side movement can be another indicator of shoddy work. I'll give an example of why it may present:

The sprocket dimensions (the little holes on the sides of a 35mm print, four per image) are extremely precise, not only in length and width, but even the angle or pitch of the cut, which must be a precise fit to the metal sprocket to eliminate shake or other problems.

When a film is released, a lab takes a master of the film and runs it through a high speed printer in direct contact with the raw stock of the print that will be released to theatres. That print is the run through a developer bath chain, dried and put onto cores or shipping reels. The two film stocks are pulled through the printer on sprocketed rollers, similar to the gears a bike chain rides on, only far smaller and far more precise.

Because the dimensions of these sprocketed rollers is small - less than two inches in diameter, the dimensions and pitch of the master film sprocket holes have to be different than the holes in the print film that rests on top of it and goes around the roller riding on a narrower part of the sprocket and a little further out from the rotational axis.

If the stock specifications are not correct, the sprockets are incorrect, or the sprockets are worn, the print film can move in relation to the master, causing the image to be printed where it slips from side to side. Because of the constant tension on the top of the sprocket holes, the vertical movement is usually less.

Lucas was constantly dic ^H^H^H fiddling with the film, making CGI changes and edits. I have the dual DVDs -the supposed original version and the "improved" CGI version. There also is a unauthorized fan version of the film on the net as a huge MP4 file. That version is probably most accurate to the original.

Fortunately for film, Sabucat and other restoration groups have made startling improvements when restoring old classics. "Mr. Smith Goes To Washington" is now gorgeous. Even earlier films have had a lot of the problems corrected, to the point that some are better quality viewing than anything since the original first runs.

It is getting to be a golden age of home theatre. The blu-ray version of "Rogue One" screens better than when I saw it in a touted local Cinemark theatre.
Reply With Quote Quick reply to this message
 
Old 05-09-2017, 03:01 PM
 
2,494 posts, read 4,768,658 times
Reputation: 943
I think this problem is called judding.
Have you seen it very often?
Reply With Quote Quick reply to this message
 
Old 05-10-2017, 05:11 PM
 
Location: Somewhere in northern Alabama
18,537 posts, read 55,453,855 times
Reputation: 32256
I've seen a LOT of film, Robert. Yes, I've seen a fair amount of it over the years.

It can also happen in theatres for other reasons. If a film gate isn't properly cleaned and adjusted it can happen. Very early on when I was a projectionist and we were playing "Love Story" first run, I neglected to notice that one of the thin chromed metal skate bands in the Norelco DP 35-70 was getting too worn. The edges of the film rode over one of them on each side of the gate to hold pressure as it went through and the light was sent through the stopped film. A thick splice hit the weakened band, and turned it into a carving tool. A 1mm skivving peeled off the edge of the print for about eight minutes before I came back to check on that projector. That 34mm wide film running through the 35mm projector never did run right...
Reply With Quote Quick reply to this message
 
Old 05-12-2017, 08:31 AM
 
40,212 posts, read 41,799,403 times
Reputation: 16749
Robert, if it's just the edges what you are seeing is probably the overscan area of a video made for broadcast on an analog TV. On video made for analog TV the edges of the video contain information like CC, copy protection signal etc. This would have been added to the film after it was converted to DVD. A CRT TV never displays that part of the video, it's off the edgeof the screen.This is an example:



It's usually on the top too. This is from Hi-8 which is analog source and when you are converting something like this to digital what you usually do is frame it with a black mask so when it's played on a modern TV or computer screen it's not "wiggling" on the edges. DVD's are digital but they were originally intended to be viewed on analog and converted to analog for display hence the reason they will have this. You can also see this on old TV programs that are being broadacsted sometimes that were converted from sources made for analog.

Modern digital video transmitted as digital of course does not need this because that information can be transmitted separately. A modern TV and DVD player can compensate for older video by mimicking the overscan area by zooming in a little. Check the setting on your TV and players.... One thing to be aware of is if you have it set to "overscan" or whatever the manufacture calls it you are unnecessarily zooming in on modern digital video also. Most TV's may already be set to do this so if you are reading this and don't watch this type of video check the settings so you can get the full resolution of modern video.
Reply With Quote Quick reply to this message
Please register to post and access all features of our very popular forum. It is free and quick. Over $68,000 in prizes has already been given out to active posters on our forum. Additional giveaways are planned.

Detailed information about all U.S. cities, counties, and zip codes on our site: City-data.com.


Reply
Please update this thread with any new information or opinions. This open thread is still read by thousands of people, so we encourage all additional points of view.

Quick Reply
Message:

Over $104,000 in prizes was already given out to active posters on our forum and additional giveaways are planned!

Go Back   City-Data Forum > General Forums > Science and Technology > Consumer Electronics
Follow City-Data.com founder on our Forum or

All times are GMT -6.

© 2005-2019, Advameg, Inc. · Please obey Forum Rules · Terms of Use and Privacy Policy · Bug Bounty

City-Data.com - Archive 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35 - Top