autogk and ITU-R BT.601

[pigee]

Hi,

I´m new to gk and autogk. They both seem promising.

In gordian knot it is possible to select/deselect the ITU-R BT.601 resizing method. I´d like to know what setting autogk uses. Standard resizing or ITU-R BT.601?

I´ve done some tests myself and i found that standard resizing method gives the best results. I have some movies with big circles in it. I mesured them both on monitor and on tv-screen. When resizing according to the ITU-R BT.601 standard circles become ovals.

It seems that lots of dvd´s don´t use the correct resizing method.

Pigee

[len0x]

As of version 1.20 AutoGK always uses ITU-R BT.601 method. Noone complained so far :)

p.s. I suggest reading sticky in this forum on the subject.

[pigee]

thx for your quick reply.

I´ve read the sticky but i feel like the discussion ends unfinished. I hoped that there was an undisputable answer, but it seems people have different experiences with it. There has to be someone who knows the absolute facts of it:)

My personal experience is that the best results are achieved with standard resizing. However, i´m new to dvd-ripping and i only ripped about 10 dvd´s where only 3 of them had perfect circles in them to mesure. I know for sure that these dvd´s do not comply to the ITU-R BT.601 method. But maybe the other 7 do. who knows? :)

anyways len0x keep up the good work coz your proggies are just awesome:)

greetz,

Pigee

[gatormac]

The ITU-R method is better IMO. They both are acceptable, but the ITU-R method is much truer to the original AR by my eyes. The standard resize gives more of a vertical stretch when compared to the source dvd.

[manono]

Hi-

...i feel like the discussion ends unfinished.

Only because TheWEF got tired of reading all of the nonsense being spouted. To get the real lowdown, just read his comments.

I know for sure that these dvd´s do not comply to the ITU-R BT.601 method.

And just how did you determine that? Did you measure the horizontal and vertical diameters of these circles when playing the DVDs on your television?

[pigee]

Indeed i measured the horizontal and vertical diameters on both monitor and TV. With standard resizing those two are exactely the same on my monitor almost the same on TV. And with ITU-R BT.601 resizing those diameters ar not the same. (not on monitor and worse on TV)

Pigee

[erdie]

very interesting

can someone actually quote the
ITU-R BT. 601 standard specification
where it says that an anamorph NTSC 720x480 frame should be
displayed at a 1,818:1 ratio on your TV, and not at 16:9 ?

[len0x]

FYI - AutoGK starting from 1.30 doesn't respect ITU standard anymore, manily because I think captures should be resized as it is. Does this ITU resizing only applies to DVDs I wonder?

[Doom9]

Noone complained so far Hmm.. I must've missed this or I'd be the first to complain. Down with ITU ! ;)

[erdie]

as I understand it from reading this thread: http://forum.doom9.org/showthread.php?threadid=64266&highlight=ITUR

ITU-R is still applied for 16:9 sources, which is wrong too IMHO

I checked this -like pigee- by taking measurements from the TV with a
tape measure.

e.g. I measured the A.R. of the Warner logo on my TV (width/height)
then I ripped it on my PC and did resize it

one time with ITU-R checked, the other time without (changed cropping so that AR error would be 0 for both cases after resizing)

while the AR without ITU-R checked almost matched the one measured on the TV (+/- 2mm error of measurement, that's < 1%)
the one with ITU-R checked was in fact over 2% off!

so explanations like this one here:
http://www.uwasa.fi/~f76998/video/conversion/

are really neat and stuff, but proven wrong in practice...

[len0x]

Originally posted by Doom9
Hmm.. I must've missed this or I'd be the first to complain. Down with ITU ! ;)

its tool late, coz now AutoGK don't use ITU standard anymore :)

[erdie]

g, I'm sorry len0x, just noticed you are the author of AutoGKnot, so it's gotta be like you say, no more ITU :)

[len0x]

I just happen to rip The Big Lebowsky R2 mentioned by The Wef in the main ITU thread. And can confirm that bowling balls look really round (I actually measured them) only with ITU option ticked. Then I tried Adaptation R1 and compared DVD playback with AVI playback (screen-to-screen) and again ITU version was the same as original DVD. I didn't use analog TV, but rather digital LCD screen for output.

So I will do some more tests and may switch ITU back on. There is no ideal solution as DVDs are mastered different - its just a matter of selecting the most used standard. And I still don't know about captures...

[erdie]

damn you're right len0x

seems like I took some wrong measurements back then

repeated the test with the Geffen logo, which is a perfect circle on TV - only with ITU checked it is a perfect circly on the PC as well (with 0% AR error)

of course DVDs can be mastered disregarding that ITU-R standard, but one thing's for sure:

only the ITU-R options guarantees that the result looks exactly as on your TV

possible tradeoff for auto-gknot: try to hit the res. that gives +/- 1% A.R. error for both ITU-R checked / ITU-R unchecked...

[Wilbert]

@len0x,

Try your test with Gladiator.

[valnar]

I think a lot depends on how you view your resulting GKnot movies. If I watch them on my Hitachi 36" TV with a VGA input, which is basically just a big 4:3 monitor, I prefer movies without the ITU option. I'm using a software player. Video rez is standard 800x600.

If I watch it on a HTPC connected to a regular analog 19" TV through a Matrox G400 video card s-video out using the DVDMax option, it stretches it appropriately, and I would want my videos using the ITU option. Since my 36" TV gets used more often, and I tend to view with BSPlayer, PowerDVD, WinDVD, etc. type software more often, I leave it unchecked.

Note: I only use Gordian Knot, not AutoGK.

-Robert

[ukb007]

It seems from the discussions the circle in the avi looks oval sometimes with the ITU on and sometimes with ITU off. I'd want my circle always look circular, no matter where and how I view it. Of course, once encoded, there's no going back. Can't there be an intelligent solution where you can tick somewhere and effect a change while playing the file? Some players do offer a simple change in the vertical dimension, although to a fixed amount.

Unbelievable that we'd have to put up with such grossness (having to view a circle as an oval or vice versa) when, outside the window, it's approaching 2005, not 1995.

I have learned to:
1. put up with very very very minor distortions of the circle (not noticeable unless you are too much of a perfectionist)
2. take some remedial measures in GK resolutions tab
3. and now with the advent of AGK-Tweaker (by gircobain), modify the avs scripts in AGK to effect a change in the output AR more to my liking.

I must mention here that I view my AGK (versions pre-1.20 through post-1.30 without the use of AGK-tweaker)-generated videos in my Samsung SyncMaster as well as my 21" Sony, and they always look the same.

Have I been lucky so far and it's time the statistics catches up with me now?

Regards.

[len0x]

Originally posted by Wilbert
@len0x,

Try your test with Gladiator.

what should I expect there ?

[Shandra]

Originally posted by valnar
If I watch it on a HTPC connected to a regular analog 19" TV through a Matrox G400 video card s-video out using the DVDMax option, it stretches it appropriately, and I would want my videos using the ITU option. Since my 36" TV gets used more often, and I tend to view with BSPlayer, PowerDVD, WinDVD, etc. type software more often, I leave it unchecked.

As I have a Matrox too on my main PC (and prefer it still vs. the ATI in my newer PC (Aldi PC bought for VHS captures (not with the Ati but a Philips TV-Card))) and have loved it so far (even with the trouble DivX5.2 gave me with it)... but you hinted me now in another view to the topic...

Calibrating your own devices ;) As I have no experience with anything apart from regular Monitors and my simple TV I cannot speak for LCD Displays - but have the ones complaining about non-itu is better fitting than itu all setup their TV Output right (So that a Video Overlay Signal is displayed the "right" way (Parts of the Video beyond the visual area of the TV or is the whole video displayed (and therefore stretched? and assuming the driver converts it properly to analogue),etc.) & calibrated their monitor right ? I just know too many friends who use to blow up the display size of the monitor to their liking and not in the way that a Xcm x Xcm square in display dpi is actual that square (not thinking about colour-calibration))...

Even if you keep to specs (and hope your Source has done also), you can never be asured that with all those hardware/software combinations possible for each User you get it for that User right.

But well, even after more than a year working with capturing VHS I am still puzzled from time to time and working on it (and there is so much that can confuse you alone in regards to chipset/etc. if you take every debate about that topic (and suggested solutions) serious)...
But so far (and with the hope that my DVD standalone resizes properly in 4:3 mode as I, since I bought me the IndianaJones DVDs wich offer the THX Test Screens, have tried to "calibrate" my capture-process to that circle) my experience is that if I stick to the guides I found through this forum (Capture Karten & Aspect Ratios für Dummies, and this side (http://www.uwasa.fi/~f76998/video/)) the ITU conversion is the right way for me.... but well, with another capture card a non-itu resize or a various capture size may well compensate for the "failure" of that hardware, or give a proper result if the drivers of that particular Video-Card are not converting properly to analogue. :sigh: IMHO best choice would be to make it optional even in AGK ( but again, than thats AGK and no confusing aspects for the user :doublesigh: ) as there are just too much parameters for each particular users environment to ever let this topic have a good ending :tripplesigh:

Edit: Mh, maybe I should have added (so doing it now) - that the resizing from captured source according to ITU is only done by me if I aim for such things as VCD/SVCD where DAR/PAR are important again - as obviously once you captured you have a *AR/1:1 ("asssumed you captured circles") Source to work with (if I understood it right) as it is PC material by then.

Edit2nd: Ok, Skip my message - it was just me after halve a year University distraction that I uploaded all my hatred vs. myself in this thread.... So for me and capturing VHS I have to seek on.... for GK (not AGK) I hope that ITU remains as an option as that is the resize method that with DVDs (and non square pixel sources) works best!

[len0x]

Ok, I've added hidden option to enforce ITU resizing to version 1.50. By default usual resizing is used, but now you have an option to change that (its a global option for the whole encoding session). At least we can stop discussing if its right or not :)