Desktop DVD-Recorder Help!

May 14, 2007 8:55 PM

Whenever I record something from TV on my Samsung DVD-120, I get a strip at the top of the screen that you can't see when you play the DVD back on the TV, but if I watch it using anything on the computer (VLC, Media Player Classic, WMP, etc.) it's always there. The strip is black and white and I have a screenshot here. I can usually fix this in Media Player Classic by using the "lengthen screen" tool in the program. But it's a hassle doing that with everything I record. If I rip the show from the DVD to the hard drive - same thing. The strip is still there. Does any MeFite know what vthe hell this is? It's driving me crazy! I've tried Googling, but came up empty. Maybe I wasn't using the right terminology with "strip"....I don't know. Any ideas??? Thanks!!
posted by Gerard Sorme to technology (9 comments total)

Do you encode your DVD files after you rip them? You could try just cropping the top few pixels, might work.
posted by parallax7d at 9:04 PM on May 14, 2007

That might be the closed captioning signal. It's not visible on a real TV, but a real TV doesn't show all the lines because of overscan.
posted by smackfu at 9:25 PM on May 14, 2007

Those are lines above the official image area that you're not supposed to see. The video signal consists of image info (that you see) and some stuff above/below the image that originally was supposed to be pure black (called the vertical blanking interval or VBI) to tell your TV how to line up the image vertically. A TV with bad VBI detection will have that vertical scroll problem that you may remember from the old days.

For decades now, the VBI has not been pure black, but instead a few of those lines (14 through 21 I think) are used to carry some broadcast data. Things like closed captioning, V-chip, Nielsen codes, etc. The image area (called active video) starts at line 22, and so that's what your TV or recording device is supposed to display. If you see the VBI lines then your device isn't framing the image right.

http://en.wikipedia.org/wiki/VBI

Now, how to fix it? No idea. Go to avsforums and see if this is already a known problem. I didn't find a thread dedicated to the Samsung DVD-R120, so you'll have to poke around in the general Samsung DVD recorders threads and see what you find. Search before posting there!
posted by intermod at 9:26 PM on May 14, 2007

I may be wrong about this, but I always thought this "strip" was the part of the TV signal that encodes the teletext information. I've been noticing it for many years - if you grab yourself an old TV and adjust the vertical... man I've forgotten what it's even called, but the setting that makes the image roll down the screen, you will see this strip at the top of the image on the TV screen.

TV sets, presumably, clip this part of the "image" out before display. Your DVD recorder, it seems, isn't quite adjusted to do this when it digitizes the image. Given that your DVD recorded is unlikely to have any of those old-school controls you might find on TV like the vertical and horizontal thingies, I think your only option is post-recording cropping, or complaining to Samsung about their crap hardware.
posted by Jimbob at 9:30 PM on May 14, 2007

(The following is not quite true, but close enough for the purpose of explanation...)

It's the tail end of the Vertical Blanking Interval (VBI) - the black is the first few lines of picture at the beginning of each frame.

Basically, a TV works by drawing a field from top to bottom. The electron gun then takes a finite time to return to the top of the screen to start the next field, so a time with no video is set aside for this purpose. A little black is included at the top of each field, just to be sure - this is normally invisible on a CRT TV as it falls just outside the visible area of the screen (look up "overscan").

The little white lines & dots are signalling codes placed inside this "invisible" area. Stuff like teletext / closed captioning, etc. The ones you're seeing there, being a bit further along in the field, are most likely internal signals for station timekeeping/cueing/switching/control.
posted by Pinback at 9:36 PM on May 14, 2007

Very interesting info! So, it sounds like my DVD Recorder is recording something that, if aligned correctly, it would not be recording?

The question is, of course, what do I do? Get a new DVD Recorder? Do any of you get this if you use a set-top DVD-Recorder and play back on a PC (rip to hard drive, make copies, etc.)?

Thanks again.
posted by Gerard Sorme at 10:05 PM on May 14, 2007

Most recorders keep that information, as much of it is useful. It's up to your playback software on a computer to ignore it.

Again, recorders generally record the whole picture. Playback devices then cut off the top.
posted by wierdo at 11:03 PM on May 14, 2007

Pinback has it right it's called: Blanking information, and normally you don't see it.

The outside 10% of the picture, normally is never seen by the everyday viewer.

Your DVD recorder is doing the right thing - and recording the full picture. It happens to contain (amongst other things) closed captioning information.

You might want to switch to the VLC Player (free, open source) - you could set it to crop a certain number of pixels as a default, and you'd never see it - just like your TV.
posted by filmgeek at 4:34 AM on May 15, 2007

Thanks, filmgeek. I didn't even know that option was available with VLC. It worked! I'm glad to know there's nothing wrong with the DVD recorder, it gets incredibly crisp recordings.
posted by Gerard Sorme at 1:05 PM on May 15, 2007