Video resolution question???

[AquaStealth]

When I play a DVD in R2 PAL format my software tells me that the video resolution is 720x576 [1.25:1].
But when i analyzed the video more thoroughly I found that the actual DAR was 960x540 pixels [16:9] and that the true video aspect ratio filled up 960x518 pixels [1.85:1].
So why does every software i use with the file tell me the resolution is 720x576 when I can see with my own eyes that this ratio isnt correct???????

[scharfis_brain]

PAL-DVD uses a pixel aspect ratio (PAR)of 1:1.094

this means, a 4:3 Fullscreen video would be 768x576 with square pixels, but due to the non-square PAR of 1.094, 768x576 is squeezed into 702 (seven zero two) x 576 pixels

to match some standards (ITU & mod 32 widths), this width gets expanded by adding borders, so it reaches 720 pixels.

this means: 720*1.094 = 788x576 , which is WIDER then 4:3.

now, to make this confusion perfect, 16:9-enhanced, called anamorphic film, is introduced.

the original 16:9 film has 1024x576 square pixels.

those pixels are at first sequeezed to the 4:3 area of 768x576, which makes an 1:1.333 PAR. (anamorphic)

but to match DVD-standards, this 768x576 pixels are squeezed to 702x576 again, and then letterboxed to 720x576.
this means, the final PAR is 1.094*1.3333 = 1.4587.

this makes the 720x576 anamorphic image being 1050x576 square pixels large.

I hope this wans't too confusing

[jggimi]

A much less technical, simpler way of understanding this:
All commercial PAL DVDs have a resolution of 720x576. (In the same fashion, all NTSC DVDs have a resolution of 720x480.)

These are NOT square pixels, such as used by your PC display. If it were, this resolution would be 1.25:1.

4:3 = 1.33:1, and 16:9 = 1.78:1.

The Display Aspect Ratio (DAR) of the DVD will either be 4:3 or 16:9. Neither of these is 1.25:1, since DVDs do not have square pixels. These are the ONLY two DARs available.

Your software DVD player will resize the video appropriately for your square pixel monitor, and add letterboxing if necessary when played full screen.

If using a standalone DVD player and a TV, the player will resize if needed, according to the shape (4:3, 16:9) of your TV, and add letterboxing if necessary.

[SeeMoreDigital]

Yep, jggimi's explanation sure is "less technical" ;)

One more thing to make a mental note of....

Your software DVD player is able to correctly adjust the aspect ratio of an Mpeg2/DVD automatically. Whether it's an anamorphic "wide-screen" DVD or a "standard/full screen" DVD. This is because an special AR signalling code has been added to the Mpeg2 video stream.

Should you ever decide to generate 1:1 (pixel for pixel) back-ups of your favourite DVD's to say, Mpeg4/AVI. You will need to manually add an AR signalling code to the Mpeg4 video stream.

Currently, popular Mpeg4 codecs such as, XviD and 3ivx include this function. But DivX does not!

For more information, please refer to my "sig" below this post.


Cheers

[AquaStealth]

Thx for all your answers, I almost got it now :)
But still I have some problems when doing a DVD backup to Xvid.
According to my calculations I should crop the file
mentioned above to 640x344 to maintain nearly the same
AR of [1.85:1] as the original file. And then use a resize
setting of 640x360 to not cut anything out of the original video.
Ive done test rips and the picture looks very similar in AR etc as the original :)
But will this rip be accepted according to scene standards or will it
count as nuked cause of some strange rule I dont know of???

According to another forumpost the width and height should always be dividable with 16. i.e. 640/16=40=OK and 344/16=21.5=Not OK
Is this true.

Problem is: I want the width to be 640 but if I use 640x352 which is commonly mentioned everywhere I will get black borders (letterbox) included in the avi :(
With Auto GK I got a movie of 608x336 [1.81:1] which means that you cut off parts of the original movie on the left/right side. :(

What should I do PLEASE HELP ME!!!

[SeeMoreDigital]

You are getting confused...

Your DVD source is anamorphic. Which in the case of an DVD means the source picture looks "squashed" up!

The horizontal pixels of a DVD image "ping out" to fill the screen. The vertical pixels remain fixed...

Have a read of my anamorphic explanation (http://seemoredigital.net/03_Video_Only_Info/What_is_an_anamorphic_encode.html).


Cheers

[manono]

Why are you helping this person?

But will this rip be accepted according to scene standards or will it count as nuked cause of some strange rule I dont know of???

He wants to rip DVDs for release on the "scene". Just what the "scene" needs, more releases by incompetent rippers. Someone put him out of his misery and close this thread.

AquaStealth, read the Rules, especially Rule 6 (http://forum.doom9.org/forum-rules.htm), and the Announcement (http://forum.doom9.org/announcement.php?s=&forumid=6). Although they are specifically about downloaded content, they apply equally to content being prepared for download.

I wrote pretty much the same thing in this Thread. (http://forum.doom9.org/showthread.php?s=&threadid=83403) That makes this new thread a cross-post, another violation. He's been a member for over a year and a half and has yet to learn what is and is not acceptable behavior around here?

[ammck55]

Thread closed...