overscanning safe zone?

logiquem wrote on 2/18/2005, 6:08 AM
I always wonder what is the safe zone for overscanning?

Explaination : as you know, even with DV, you get some black borders on either sides of your image.

Altough these will not be visible on NTSC, you must mask them elegantly If you care for computer DVD movie display. The problem i have with this is to determine what is the border range i can mask, being assured that no NTSC monitors will display them.

I know that overscanning is variable with different NTSC monitors (BTW, are LCD/plasma the same than conventional CRT regarding this specific issue?), but is there a generaly accepted "safe zone" here (say 8 pixels borders, or whatever...) ?

Is this an issue, or am i paranoïd this morning...? :-)

Comments

Chienworks wrote on 2/18/2005, 6:31 AM
I would say you are paranoid. ;)

Maybe my DV camera is different, but i don't have black borders when i capture from it. I do get them when i digitize VHS from an analog->DV converter, but since they're black i don't worry about them.

Televisions vary a lot! You really can't come up with any standard amount.
BillyBoy wrote on 2/18/2005, 10:14 AM
Every TV will have a slighly different overscan, varying even within the same model line. As a very rough yardstick it seems CRT type TV's average around 10% while plasma and LCD generally (there are exceptions) tend to be less. If you're losing sleep over a handful of pixels, I agree that's being paranoid. I'm paranoid over tiny varations in levels and hue and accordingly probably spend too much time fiddling with the color corrector filter. Welcome to the club. If you're a regular reader of this forum you'll see many are somewhat obsessive over something just like someone into cars spending endless hours trying to get a few more hoursepower out of his engine.
Laurence wrote on 2/18/2005, 10:48 AM
I am curious about this subject for a different reason. When using deshaking software, the edges of the frame get quite badly mangled. I want to make a "letterbox" matte to cover this. I figure it won't even be visable on most TVs and it will keep things looking crisp on a regular monitor. What would be a good size for the hole in the middle of this letterbox matte?
rs170a wrote on 2/18/2005, 11:18 AM
The SMPTE standard is a 5% border for "Safe Action Area" and 10% for "Safe Title Area". You would think that, with all the advances in electronics and manufacturing technology that this would no longer be applicable. What I'm seeing is that, as consumers demand lower prices, the quality goes down accordingly. I guarantee that a cheap no name TV from a big box store will not hold it's quality as well as a more expensive name brand set.
As BillyBoy says though, the rules have changed for displays like plasmas, etc. This is where you have to do some experiments on your own. I been involved in producing material for video projector viewing and I end up tweaking the video a lot more than I would for normal TV viewing simply because of all the factors involved (type of projector, type of screen, brightnees of viewing environment, etc.).

Mike
riredale wrote on 2/18/2005, 11:34 AM
I don't worry about the vertical black bars I get when showing a 4:3 still, simply because they are so narrow to begin with (note: you get those bars because DV is NOT 4:3, but actually slightly wider).

You can run your own test with the TV monitor you have hooked up to your editing station. You do have a TV hooked up, don't you? If not, you should, simply because the Vegas preview window can't show what the video will truly look like. In my case, the TV overscan roughly matches the 10% value (5% for each side) that Vegas uses as a default for the overscan overlay.

I would have thought that purely digital sets (DLP, Plasma) would not have any overscan at all, since calibration settings don't drift over time as they do with analog processes. I don't have such a set, so I could be wrong.

As for the "SteadyHand" issue, I use the amount of cookie cutter that is necessary, and to make its presence even less noticeable I slowly keyframe it in and out, perhaps over 20 seconds or so each way. Viewers on overscanned sets won't even see the cutout, and viewers on non-overscanned displays won't usually notice it.

Of course the idea is to use as little as possible. In a segment I'm currently working on, the cookie cutter has a minimum value of 0.47 for the Size variable (0.5 means no visual effect) to hide most, if not all, of the border motion. Just do what you think looks good.