Image cut on the borders

[correioelet2002]

Hi

Well, something's gone wrong here and I can't figure out why... Even though I have an "old-fashioned tv" (no full-screen), when I encode my mpgs with aspect ratio 4:3 (that should be right from what I know) the VCDs still get their images a little bit cut on the borders, and not only on the sides, but also above and below.

It is important to point that this happens only on standalone players. My computer plays them correctly.

Any idea on what's going on?

Thanks!

[correioelet2002]

Oh! I forgot to mention: I know people use FitCD to get round this, but the program only reads avi and Divx, and I want to encode from other sources without having to encoding them to avi and THEN back to mpg.

[antonv]

That's what happens if you play VCD on your DVD player. Remember that the video file on the computer is measured in pixels (width x height) and TVs, especially the old ones are measured in lines (625 lines or so). the DVD player converts your rectangular video in pixels into not as rectangular video in lines.

[FulciLives]

Actually nothing is wrong.

What you are talking about is known as OVERSCAN

This is from the GLOSSARY on this very website:

Overscan
The area at the edges of a television tube that is covered to hide possible video distortion. Overscan typically covers about 4 or 5 percent of the picture.

However a computer monitor does not have OVERSCAN so when you watch a DVD or a video capture on the computer you are actually seeing the very edges (all 4 sides) of the image THAT YOU NORMALLY wouldn't see on a TELEVISION.

For things made for TV there is little point in compensating for OVERSCAN but a lot of people like to do it for movies and sometimes that does make sense because in a movie theatre you are seeing the extreme edges MORE-SO than on a TV with OVERSCAN. Some movies, depending on the cinematographer and/or director make use of the extreme edges as far as image composition but most modern movies (usually post the late 1970's) make sure they keep anything important off of the edges since they know that OVERSCAN is a TV issue and ultimately more people will see any given movie on VIDEO than in a MOVIE THEATRE.

- John "FulciLives" Coleman

P.S.
It is important to note that if your TV has OVERSCAN of 5% or less you are more or less very lucky or have a very well built (and likely expensive) television. Most televisions have more than that. Also every TV is different. One TV might show more on the bottom than another whereas one might show more on the left than another etc.

[correioelet2002]

Thank you very much for a long and complete answer!

Overscan hasn't been a REAL problem since my vcds are usually made without subtitles, but I guess when the time comes and I have to worry about this, I'll have to convert whatever video I got first to .avi and then back to .mpg. That will be the only drag, but that's not anything to keep me from sleeping I guess.

[FulciLives]

Thank you very much for a long and complete answer!

Overscan hasn't been a REAL problem since my vcds are usually made without subtitles, but I guess when the time comes and I have to worry about this, I'll have to convert whatever video I got first to .avi and then back to .mpg. That will be the only drag, but that's not anything to keep me from sleeping I guess.

I don't understand why you would have to convert from WHATEVER to AVI and then to MPEG

I mean that doesn't make any sense?

If you want to compensate for overscan then this can be done with TMPGEnc or if you use another MPEG encoder (such as CCE or MainConcepts) it can be done with an AviSynth AVS script.

Basically the concept is this ... you resize the image you have to something slightly less than your target.

For instance ... let us say you have a DVD source that is 720x480 and you are encoding it to VCD which is 352x240 ... well you resize your video to something like 336x224 and then add a border of 8 pixels all around to get back to the VCD standard image of 352x240

This will actually introduce a very slight aspect ratio error but it will be so slight as to not really be noticeable. The benefit is that you have the full image but it is slightly smaller with black all around. Thus when you watch it on a TV with OVERSCAN you get the black border cut off but not the image (or at least less of the image than if it wasn't resized).

You don't have to use FitCD or AviSynth scripts to do this. If you can open your source in VirtualDub then it can be done there using the resize filter and then you can frameserve to the MPEG encoder of your choice. If you can open your source directly in TMPGEnc then you can do it with TMPGEnc

So there is no point in taking your source and first converting it to AVI

- John "FulciLives" Coleman