1440 x 1080, do you go to 1964, and then to 1920?

[DarkT]

When I am dealign with 720x480 sources, to convert the "pixels" to square with least possible distortion, I do like this:

720x480 --resize-> 873 -crop--> 848. Ending with 848x480

1440x1080 seems to have a similar thing about it, so would I go liek this:

1440 --resize-> 1964 -crop--> 1920. Ending with 1920x480
?

Or do you go to different resoltuions with it?

[Keiyakusha]

720x480 --resize-> 873 -crop--> 848. Ending with 848x480
That's not good. First of all you (probably) cropping good pixels, secondly there is no guarantee that by doing so you fighting distortion and not creating distortion. Also there is no guarantee that when DVD was mastered, width was scaled correctly. It can be 702 real image + 18px black borders and you need to resize 702 to ~853 to get everything right or it can be cropped a bit and with no black borders, so you need to resize it directly to 848x480 to get things right. There also can be different height because of 6px of black borders at the top which can affect target aspect ratio. I made up this numbers but the point is to check by your eyes, preferable on round objects.
EDIT: well my English is not good, but I guess you understand what I mean :P

1440 --resize-> 1964 -crop--> 1920. Ending with 1920x480
And this definitely should NOT be like that. Just 1440->1920 resize

[DarkT]

That's not good. First of all you (probably) cropping good pixels, secondly there is no guarantee that by doing so you fighting distortion and not creating distortion. Also there is no guarantee that when DVD was mastered, width was scaled correctly. It can be 702 real image + 18px black borders and ypu need to resize 702 to ~853 to get everything right or it can be cropped a bit and with no black borders, so you need to resize it directly to 848x480 to get things right. I made up this numbers but the point is to check by your eyes, preferable on round objects.
EDIT: well my English is not good, but I guess you understand what I mean :P


And this definitely should NOT be like that. Just 1440->1920 resize

http://forum.doom9.org/showthread.php?t=134911

Naturally you check with your eyes.

The cropping from 872/873 to 848 sure does kill a few good pixels, since it's cropping though it causes n distortion. does allow for a good resolution ion terms of AR and mods

[Keiyakusha]

Don't understant what you want to say. Whoever tells that you always should do exactly the same resize/crop etc in case of DVDs is wrong.

[DarkT]

*sighs* nobody says to always do the same thing. however, there is a case to be made for distortions, and what are the ways to deal with them. and RESIZING directly does not quite do that. That's all. What I am askign in this thread, is how to deal with such distortions due to non-square pixels with 1440 thingy.

[Keiyakusha]

1440 thingy is just resized. it uses sar 4:3

[DarkT]

I am not convinced. 1440x1080 is rectangular pixels, not square pixels... So, I dunno *shrugs* *is hopeful for 2b's response*

[Keiyakusha]

1440x1080 is rectangular pixels
Yes. As I said it uses 4:3 sar. Apply it to 1440x1080 and see what resolution you will get. Believe it or not, it will be 1920x1080
If you want to talk to some specific person - use PM.

[DarkT]

I do not beleive things are that simple. I beleive there is a distortion invovled which needs to be corrected, somehow. You have disregarded this with the 720x480 example, so I will assume you donot understand what I am talking about, though it's as liekly that I don't understand what I'm talking about. *shrugs*

[Inspector.Gadget]

I beleive there is a distortion invovled which needs to be corrected, somehow.

Based on WHAT evidence? DVDs require people to deal with ITU versus non-ITU dimensions and pixel aspect ratios. Blu-ray discs have no such ambiguity. The ONLY situation in which you would need to do the same for a Blu-ray would occur where someone at the studio really screwed up ... but without the original master to compare the encoded Blu-ray to, you'd never be able to find out.

[board123]

I do not beleive things are that simple. I beleive there is a distortion invovled which needs to be corrected, somehow. You have disregarded this with the 720x480 example, so I will assume you donot understand what I am talking about, though it's as liekly that I don't understand what I'm talking about. *shrugs*
1440 / 1080 = 4:3
1920 / 1080 = 16:9

1440x1080 is just anamorphic 1080p packed into a 4:3 aspect ratio. There is no distortion going from 1920 to 1440; it's just a difference in pixel aspect ratio. The same idea applies to DVDs with 720x480 resolution. It's 16:9 packed into a 3:2 ratio. To avoid distortion, you first need to know how much distortion there is to begin with. It sounds like you don't know that.

[Sharc]

16:9 NTSC DVD Source:
PAR = 40:33 = 1.2121 (mpeg4 standard)
1.2121 x 720 = 873 (your example => ok)

Blu-ray source:
for 1440x1080 the PAR is always 4:3 = 1.33333.
1.3333 x 1440 = 1920.
So you have it to resize to 1920 x 1080 for obtaining an undistorted picture. If the picture should still be distorted, your source does not follow any standard but is probably crap.

[DarkT]

Great! thanks guys :) I needed that extra explanation to get me to see how in dvds it is different vs HD. Thanks!

[2Bdecided]

The difference is that SD comes from a defined-in-the-1980s digitisation of a 1950s video standard, and so has these "quirks".

Whereas the 1440x1080 is simply 1920x1080 square pixel squashed by a factor of 4/3 (1.333...). It should never have any quirks.

The fact that 1440 is twice 720 is almost a coincidence. It doesn't mean you need to go through the "pain" that you do with 720.

Cheers,
David.

[DarkT]

Yeah... the whole 720 being half of 1440 was like "HELLO! OBVIOUSLY ITS THE SAME THING! NEED HANDLE DISTORTIONSSS" I'm glad then... it's... finally... over? Yayyyy.

It's finally... Over... And I won't ever have to tr and get tha ITU/BR-whatever-U document again! yayyy, unless ofcourse I have to deal with SD stuff again...

Ranting. Sowwy. Thanks guys.