Slightly streched image.

[brucevangeorge]

I am converting some Star Trek DVDs. The original picture is at 640 x480 resolution. However, its slightly blurry. I have found that it keeps the same detail (minus artificial grain) in 480 x 360 as the original. All the "fine" textures look the same.

But whenever I downsample... the image comes out to 480 x 368. Despite me trying to force it to keep 4:3 aspect ratio.

This is a section from the Help file with AutoGK:


ITU-R BT.601 Standard is an official resizing method for DVDs in hardware, however most software DVD players (like PowerDVD or WinDVD) do no use it which results in height that is ~2.5% stretched. Different sources (even DVDs) can be mastered with or without ITU standard which means that there is no universal setting that will work in all cases. Check out the forum and its discussions on the subject. Simple user guide for this option is: if you feel like your encodes come out a little bit stretched vertically then turn this option on, otherwise leave it off.

I tried with and without. It does absolutely nothing. Problem persists.

[setarip_old]

Hi!I am converting some Star Trek DVDs. The original picture is at 640 x480 resolution.640x480 is not a DVD-compliant resolution...

[brucevangeorge]

Hi!640x480 is not a DVD-compliant resolution...

Well that's what I get out of VLC when I go "snapshot".

In that case there is still a problem. In VLC, the display window at 1:1 zoom is 720 x 540. When I save snapshot its 640 x 480. When I encode with AutoGK its 720 x 480 (log says its original resolution).

But that makes no sense. How can it be 720x480? The original material is 4:3. The original shows for TV.

[setarip_old]

How can it be 720x480?Because that's one of the DVD-compliant resolutions - in this case, full-sized NTSC format...The original material is 4:3. The original shows for TV.Please clarify - Is your source material a DVD or something else?

[brucevangeorge]

Please clarify - Is your source material a DVD or something else?

Source is VOB. Ripped using Decrypter. Then stiched together with VobMerge 2.5.

[setarip_old]

If you are saying that your source IS a DVD (comprised of .IFOs, .BUPs, and .VOBs) that you ripped using DVD Decrypter, then the resolution of this NTSC DVD is 720x480.

Load one of the .VOBs into GSpot and post a screencapture back here...

[brucevangeorge]

If you are saying that your source IS a DVD (comprised of .IFOs, .BUPs, and .VOBs) that you ripped using DVD Decrypter, then the resolution of this NTSC DVD is 720x480.

Yup. I had all the files. I removed everything but the main "movie" and joined each disc together.


Load one of the .VOBs into GSpot and post a screencapture back here...

Here you go....

[manono]

640x480 is a 4:3 NTSC DVD when resized. The reason you get 480x368 rather than 480x360 is because AutoGK (rightfully, in my opinion) resizes by Mod16 (height and width divisible by 16). Because of additional cropping it may do, there will be very low AR Error. If for some reason you insist on them becoming 480x360, you'll have to encode them yourself manually.

[Brother John]

GK is a little more flexible. On the "Resolution" tab above the output resolution slider you can use "W-Modul" and "H-Modul" to set the desired mod value. E.g. 360 is mod8.

[brucevangeorge]

So I take it that Xvid encodes in 16 pixel blocks? And not 8?

[Brother John]

You're right. Well, almost right, but a 16x16 macroblock is indeed the most important unit. For Xvid to work at full efficiency you need a mod16 resolution. And as long as you do a resize it's generally a good idea to stick to mod16.