Aspect Ratio question

[Backflip]

I'm encoding Appleseed (PAL, Eng) in anamorphic frame. DVD case only has 16:9 aspect ratio mentioned. When checking by square pixel; 0% AR error in GKnot gives 1.778. In the AR tab of XviD I plan to use X = 16 : Y = 9.

However in the past I encoded a movie (Boogeyman) with 16:9 and 1.78:1 stated on the DVD case and that time I used X = 178 : Y = 100. However I didn't check what the square pixel 0% AR error value was.

Should I actually assume all movies stating 1.78:1 or which just have 16:9 on the case are really 1.778:1 and should be encoded using X = 16 : Y = 9 in the XviD AR settings?

I'll remember to do the check using the square pixel value from now on I think. I guess I should copy the Boogeyman DVD to HDD again to check if that 1.778 value give 0% error too :/

Thanks for any confirmation on this etc :)

p.s. encoded a little bit of Appleseed. MPlayer prescales the X = 178 : Y = 100 to 704x560 => 998x560 and the X = 16 : Y = 9 to 998x560. Looks like it don't matter at all, hhmm. MPlayer still however recognises that the AR is 1.78:1 or 1.77:1 respectively.

[jggimi]

...Should I actually assume all movies stating 1.78:1 or which just have 16:9 on the case are really 1.778:1 and should be encoded using X = 16 : Y = 9 in the XviD AR settings?...DVDs have only 2 Display Aspect Ratios - 4:3 and 16:9. But films are made with all sorts of aspect ratios.

You can look up your films at www.imdb.com -- the ARs are often listed in the technical specs.

For example, Boogeyman (2005) was filmed with an AR of 1.85:1. If the transfer to DVD kept that AR, then it would have some letterboxing.

Appleseed (1998) or Appleseed (2004) don't have any technical specifications listed.

[Backflip]

Yip, 4:3 or 16:9. What should I assume is the correct AR of Appleseed (2004) considering it doesn't say it on the Region 4 DVD case. Only thing mentioned is 16:9, which is (said to be) usually around 1.78:1.

On second thought, in GKnot if you use the usual 16:9 or 4:3 option (depending on whether your DVD is 16:9 or 4:3) and crop down you get the aspect ratio on the side, which is stated as 1.787 (after cropping) for Appleseed, so on this basis it must be 1.78:1, sweet :)

Boogeyman Region 4 PAL DVD there is specifically stated AR of 16:9 - 1.78:1, there is no mention of 1.85:1. 1.78:1 is on the DVD box itself. This is also stated here (http://www.dvdunlimited.co.nz/user/movieDisplay.php?movie_id=1003464) and here (http://www.dvdtimes.co.uk/content.php?contentid=57450) ("The film is presented anamorphically at a ratio of 1.78:1 and demonstrates no technical problems to speak of"). On the otherhand on DVDAnswers.com and Amazon.com it says the AR is 1.85:1, so on the back of the official DVD case, for R1 etc, it must say 1.85:1? I've got the PAL R4 DVD and as above, it states 1.78:1. To be frank I can't remember what sort of cropping I used though, I'll have to re-rip and re-check now that I know where to look in GK for approx. AR figures. Before, I was just using the AR stated on the DVD case. I mean if you can't trust approx. figures on the box what can you trust? :/

Thanks for your help, jggimi :)

p.s. as I understand it, if original presentation of Boogeyman was in 1.85:1 yet the AR of the R4 DVD is 1.78:1, then that'd mean some of the image is chopped off, and that the R1 DVD transfer shows more picture? If that's the case it'd quite disappointing (even though the movie is pretty bad anyway :P)

[Abond]

The way I am understanding this is that 1.78:1 is at square pixels as in computer display. But TV pixels are not square, then it becomes 1.85:1 for the TV.

[Anonymouses]

Appleseed (1998) or Appleseed (2004) don't have any technical specifications listed.

The Appleseed movie which is the one from 2004 is also 1.85.

[jggimi]

Yip, 4:3 or 16:9. What should I assume is the correct AR.....in GKnot if you use the usual 16:9 or 4:3 option (depending on whether your DVD is 16:9 or 4:3) and crop down you get the aspect ratio on the side, which is stated as 1.787 (after cropping) for Appleseed, so on this basis it must be 1.78:1...As I mentioned, DVD's have 2 possible DARs: 4:3 and 16:9. But film formats and lens systems vary dramatically, and films can have all sorts of ARs. For widescreen releases, the DVD authors will typically add letterboxing in order to present the proper AR when played back with the authored DAR.Regardless what the AR of the film is, it can be authored with either DAR. The only difference between 4:3 and 16:9 in the video stream is the number of pixels used for letterboxing. I have never paid any attention to any AR "printed on the box." I expect the marketing department confuses DAR and AR.

You won't necessarily need to know the original AR, anway. If GKnot is set to use the proper DAR, and you have cropped away the letterboxing -- you will then have the original AR, regardless what idiocy is printed on the box.

.... however, due to resizing limitations, you may not be able to match the AR exactly in your resized AVI. GKnot will show you the aspect error, if any.

Let's use Boogeyman as an example. As I mentioned above, it was filmed in 1.85:1. But 1.85:1 is NOT a valid DAR. In order to playback at 16:9 or 4:3, the authors have two choices: Add letterboxing, or crop the source. Most widescreen releases I've seen have chosen letterboxing over cropping.

You have the disc -- look at some of the source video images, in Gknot's display window. Does it have letterboxing? If so, then the authors added letterboxing, and therefore your source content is NOT 1.78:1 or 16:9, as printed on the box.

[Backflip]

I too never trust what's on the DVD case especially after finding that The Machinist on the NZ PAL R4 DVD actually has 1.85:1 on the DVD case while the movie is really about 2.35:1 (which was confirmed in GKnot later).

A picture of Gordian Knot (not following .601 standard). I have cropped only 2 pixels needed to get rid of all mess on edges. If I were to encode normally - 1.783 would be closest as I see it (according to Gordian Knot)?:

http://img460.imageshack.us/img460/4812/001appleseed1rt.th.jpg (http://img460.imageshack.us/img460/4812/001appleseed1rt.jpg)

Appleseed image without cropping:

http://img284.imageshack.us/img284/2701/002appleseed2yc.th.jpg (http://img284.imageshack.us/img284/2701/002appleseed2yc.jpg)

Just out of interest I ticked Follow ITU-R BT .601 Standard I get this however:

http://img267.imageshack.us/img267/241/003appleseed8kr.th.jpg (http://img267.imageshack.us/my.php?image=003appleseed8kr.jpg)

This must be the difference. Only thing is I don't know exactly when to use Follow ITU-R BT .601 Standard :(

When exactly do you follow ITU-R BT .601 standard?

[Backflip]

I just had a read of some threads and it still seems unclear when to use Follow ITU-R BT .601 Standard, but would you say it would be best to follow Follow ITU-R BT .601 Standard in this case, jggimi? If this is the case it's a bit of a curve ball that these DVD's actually follow the standard because I rarely see it. The casing would be correct having 1.78:1 or just 16:9 on them too I think since they follow a different resizing method.

I use the anamorphic frame when encoding, so to fix the AR of Boogeyman and Appleseed rips without reencoding I just need to give a 1.85:1 DAR using MPEG4 Modifier? Is this right? Would doing that still be the same as if I reencoded all over again (giving 1.85:1 in the XviD AR settings)?

[jggimi]

The user community is split on whether or not to use the ITU standard. Here's a short, highly edited excerpt of what TheWEF, creator of GKnot, has to say on the subject, from Resolutions, Aspect Ratios And The ITU-R BT.601 Standard (http://forum.doom9.org/showthread.php?t=42708). I strongly recommend reading that if you have further concerns about how to set AR appropriately in GKnot....if the source is any kind of standard video, like broadcast, dvd, vcd, svcd, vhs, hi-8, any capture.avi,...anything, the values in the [ITU standards] table are correct....

...now what's this ITU checkbox in gknot?

if you leave it checked gknot will simply follow the standards and use the PAR values from the table - highly recommended.
if you enter a custom PAR value in "other..." or use the "select" button the checkbox does not have an effect anyway.

so why uncheck it?

if you resize a full non anamorphic ntsc-dvd frame (720x480) to 640x... according to CORRECT standards you get 640x468 and that is NOT a display aspect ratio of 4/3.
if you watch it on your 4/3 computer monitor using a 4/3 desktop resolution (e.g. 640x480) the frame does NOT fill the screen.
when you watch the dvd with your software dvd player (e.g. powerdvd) the frame DOES fill the screen. why? because the programmers accepted a slight AR-error in order to avoid black bars in full screen. the players do it WRONG, but you can't see it because the difference, the AR-error, is too small. you could see the black bars though, so...
some people prefer to resize like the software dvd players do, so they uncheck itu.....

here are reasons i can think of to uncheck itu:

1) you know for certain that the dvd has not been mastered correctly.

2) you are willing to accept the (slight) ar-error, because...

a) you do NOT crop (keep the complete frame, no autocrop,...) a non anamorphic movie and want to play it on a 4:3 computer monitor ...WITHOUT black borders. this means the movie will be resized to true 4:3 display aspect ration although technically this is not correct.

b) you do NOT crop (keep the complete frame, no autocrop,...) an anamorphic movie and want to play it on a 16:9 computer monitor ...WITHOUT black borders. this means the movie will be resized to true 16:9 display aspect ration although technically this is not correct.

[Backflip]

As I see it, there is no question about it, I need to stick to Follow ITU-R BT .601 Standard on this occasion if I am to get the correct numbers - i.e. a 1.85:1 aspect ratio which has been stated to be the correct aspect.

My video is encoded at 704x560 with a DAR of 1.78:1. I shall give it a 1.85:1 DAR and all should be good, correct? :)

[Backflip]

If I add a 1.85:1 DAR does MPEG4 Modifier alter anything apart from that DAR? No reencoding is done, correct?

[Anonymouses]

If I add a 1.85:1 DAR does MPEG4 Modifier alter anything apart from that DAR? No reencoding is done, correct?

Yes, no reencoding is done. It just changes the DAR info.

[Backflip]

Thanks :)

p.s. just want to change the DAR instead of adjust it through the media player because I use XBMC for playing media, which is sweet when detecting the DAR. Not so great at actually adjusting the AR in the settings though :)