Changing Resolution Undesirably?

[hamid22689]

Hello there,

I have a few dvds which I want to convert to avi.

Actually, the original resolution of dvds are 720x480 (i.e. 3:2) which is shown in virtual dub or any other dvd encoding software. But during the play in any player, there are two blank spaces (as horizontal black bars) above and below the screen. So, the dvd resolution (720x480) is by considering these bars and if we neglect them, I think it will be something around 720x400 which is simply 16:9.

So, I have two questions:

1- Are all dvds like this case. I mean are they all as 3:2 in original and 16:9 by neglecting the black bars?

2- For encoding, (in virtual dub or other encoders), if I select: "keep the original resolution", the encoder sets the output as 720x480 and meanwhile, removes the black bars. So the result will be 720x480 which doesn't have the black bars and therefore, the video is stretched vertically which is abnormal.

So, should I change the dvd resolution during encoding and set the output as 16:9?


I thank everybody who can give me a comprehensive answer.
Regards,

[Baldrick]

1: They can be in 720x480(NTSC) and 720x576(PAL) and with Display Aspect Ratio with either 4:3 or 16:9 so the image will be resized when you play it. They can also contain black borders so you can get wider than 16:9 like 2.35:1 video. Read http://en.wikipedia.org/wiki/Aspect_ratio_(image)

2: I would convert to a resolution with same aspect ratio as the source, so called pixel aspect ratio, like 720x480 with 16:9 to ~720x406, 720x480 with 2.35:1 to 720x306. If any black borders then first crop the black borders and then resize to 16:9 or 2.35:1 resolution. Or just use AutoGK, FairUse Wizard to convert DVD to AVI and they will resize and crop automatically.

[jagabo]

You can also leave the resolution as it is and use the MPEG4 DAR setting to specify the aspect ratio of the final displayed picture (4:3 or 16:9). Not all players will respect the DAR setting though.

[hamid22689]

Thank you both,
So, is there any way to detect the original aspect ratio of dvd?
As I know, the encoders only show the resolution.

I think aspect ratios 4:3, 16:9 and 2.35:1 can be distinguished by the eye, anyway I'd like to know if there is a method to check it.

[jagabo]

There is no 2.35:1 DAR on DVD. DVD only comes in 4:3 and 16:9. A 2.35:1 movie would be padded with black borders to make it 16:9 or 4:3.

GSpot or MediaInfo can tell you the DAR of the VOB files. Or you can just eyeball it. 16:9 movies usually say something like "Enhanced Widescreen" or "Anamorphic Widescreen" on the case.

[TBoneit]

I use GSpot. However you eyeball it. If it looks widescreen then the DVD is 16:9 otherwise it is 4:3.

The Video resolution bears no relation to the display resolution. a SVCD of 480 by 480 is usually a 4:3 display for example.

[RabidDog]

Eyeball the Box.. full screen=4:3
widescreen is everything else (16:9, 2.35:1 etc, etc)

[jagabo]

I have a few "widescreen" DVDs that are letterboxed 4:3.