Reliable way to find out the Aspect Ratio of a movie ?

[iparout]

Hi. I am trying to encode Jeepers Creepers region 2 DVD. When I load the vobs into DVD2AVI and hit preview, it says that the movie is 4:3. However, when I load it into the preview window of GKnot and select 4:3, the faces seem stretched on their vertical axis. This stretching also occurs in DVD2AVI preview. So I am wondering... Could DVD2AVI be wrong ? So far I've encoded around 200 movies and only 1 time was DVD2AVI wrong.

I searched for the DVD on the net and found out that it's Anamorphic 1,78:1 or at least that's what it says on the box. When I select anamorphic in GKnot, the proporions of the faces seem more correct than 4:3, however, as I already said, the preview option of DVD2AVI shows them stretched. This may happen with other movies in the future as well..

So my question is, which is the most reliable way to find out the correct AR of a movie ?

Thanks in advance.

[jggimi]

You asked:So I am wondering... Could DVD2AVI be wrong ? Then you wrote:So far I've encoded around 200 movies and only 1 time was DVD2AVI wrong. I think you've answered your own question. DVD2AVI will be wrong 0.5% of the time....Anamorphic 1,78:1 or at least that's what it says on the box...All PAL DVD's will be 720x576, or 1.25:1. Then, the DAR will either be 4:3 (1.33:1) or 16:9 (1.85:1). So a 1.78:1 DVD will have letterboxing, but can be in either 4:3 or 16:9 DAR. The difference will be the amount of letterboxing, and, of course, the resolution after letterboxing is stripped away. What's printed on the box is always the adjusted aspect ratio of the non-letterboxed part of the video. It's never the DAR.

The DVD2AVI preview is unresized, and will be in the DVD's "native" aspect ratio, using square pixels, 1.25:1, and won't help you determine if the DAR is correct or not.

How do you determine which DAR to use? In Gknot, its pretty easy. Strip off all letterboxing, and pick the DAR that gives the resolution closest to the 1.78:1 aspect ratio printed on the box.

[iparout]

Yes, that's what I figured. After cropping the black bars, I get the 1,78:1 by using the 16:9 AR. Thanks for the info.

[ppera2]

By my experiences more than 20-30% DVD has wrong AR in DVD2AVI.

I backuped lot of them, many is not so good quality, and probably that's reason for so big percent.

Seeking part with circle or similar is only sure methode for me.

[mpucoder]

I seem to recall that DVD2AVI is reporting the menu dar, not the movie's.

[jggimi]

Hmmm...that confuses me, because when I used DVD2AVI, the .VOBs I've worked with have already been IFO parsed and have always been a single angle PGC, without menus (SmartRipper in Movie mode, DVD Decrypter in IFO mode).

[Doom9]

@mpucoder: is the menu dar really stored in the non menu vobs? That would kinda surprise me.

@all: dvd2avi isn't wrong. It reads the DAR flag of the MPEG2 video stream. Now it happens that for some wicked reason that flag says 4:3 while the movie is really encoded in 16:9. If you were to check the video attributes in the ifo file (ifoedit makes that rather easy) you will normally find that in the ifo it says 16:9. I haven't seen dvd2avi report something inaccurate, but it does happen that the dar of the vobs is wrong. Apparently players use the ifo to determine the dar since these discs are displayed in 16:9 on both standalone and software dvd player.

[mpucoder]

Maybe I had the wrong program, or maybe it's this same problem of vob file vs ifo file values.

[iparout]

Originally posted by Doom9
@mpucoder: is the menu dar really stored in the non menu vobs? That would kinda surprise me.

@all: dvd2avi isn't wrong. It reads the DAR flag of the MPEG2 video stream. Now it happens that for some wicked reason that flag says 4:3 while the movie is really encoded in 16:9. If you were to check the video attributes in the ifo file (ifoedit makes that rather easy) you will normally find that in the ifo it says 16:9. I haven't seen dvd2avi report something inaccurate, but it does happen that the dar of the vobs is wrong. Apparently players use the ifo to determine the dar since these discs are displayed in 16:9 on both standalone and software dvd player.

So are you suggesting that what the ifo file says is always correct ? Is that the most accurate and reliable way to find out the AR of a movie ?

[Doom9]

@iparout: the most reliable method I know of, yes.

[jggimi]

Well, I've always thought my "Gknot method" was the most accurate, since you're examining the content itself to determine the correct DAR (if need be). Of course, the published aspect ratio (on the box, the distributer's website, or www.imdb.com) might be wrong, and I admit to also looking at faces, clocks, wheels, and any other obvious arcs to determine if I've gotten it right (or if DVD2AVI has). Not to speak for Doom9, but if players use the IFO, then an IFO examination will likely be the most accurate.