Wrong Aspect Ratio

[WorBry]

Hi,

I'm not sure how AutoGK determines the aspect ratio, but many times it is not correct. For example I just encoded a 16:9 PAL movie at 75% quality and it came out to 704x400. The objects looked a bit narrow so I checked it in Gordian Knot at the same bitrate. With the default 32x16 W-H modul, Auto-crop>Smart-Crop-All gave 704x384 and the picture looked correct. To confirm I changed the H-Modul to 1 and Autocrop>Smart-Crop-All gave 382, Pixel-Crop>Smart-Crop-All gave 383 and PixelCrop alone gave 386. So, 384 was the correct height for H-Modul 16. I dont understand why AutoGK would choose 704x400. I tried it again using Custom Size (AutoWidth)but with the same result. Looking back through my archives I've found a few others. I know the advice is to always check Preview before committing and that there are some interventional tricks to change the AR if it doesnt look right, but then you lose the simplicity of AutoGK. I hope you can arrive at a fix for this. Thanks.

[len0x]

Current AutoGK doesn't follow ITU standard as GK does by default. If you untick that option in GK you should get the same result as with AutoGK. Its a feature.

[WorBry]

Hi Lenox,

Thanks for your reply.

OK, so the info associated with the "Follow ITU-R BT.601 Standard" option in GK states "It's recommended to leave this checked.
It is the correct resizing method for DVD. If you uncheck 'ITU-Standard' the resizing method will be similar to the regular
one used in software DVD-players like WinDVD and PowerDVD and described in most guides. But actually this will result in an aspect ratio that is ~2.5% off!This fact was pointed out to me by jackei, the author of dvd2avi."

So that explains it, but why would I want to uncheck if it gives an incorrect AR and one that is noticable? My obvious question then is - is there any intent to include the ITU standard option in AutoGK?

You probably need people like me like a hole in the head, right?

[len0x]

Originally posted by WorBry
My obvious question then is - is there any intent to include the ITU standard option in AutoGK?


No.
Also please search the forum. i.e.: http://forum.doom9.org/showthread.php?s=&threadid=75998

[WorBry]

OK, I've read the thread and am even more confused by the conflicting opinions. Basically, all I want to know is what is recommended (ITU on or off?) for the most accurate rendering of "true" DVD display dimensions with DivX encodes played back on:

1. PC - WMP or CoreMediaPlayer (Not PowerDVD)
2. Standalone DivX/DVD player to TV

Clearly, like anyone, I would want to avoid having to encode separately for these two playback modes if at all possible.

I know this forum is largely populated by people with deeper knowledge and experience of this stuff - I'm just a humble user trying to get the best possible picture.

Thanks.

[Mnl]

Hi WorBry

Actually I don't think you will get a definite answer to that question. Different people have different opinions when it comes to that standard. Assuming that you have read the sticky about Resolutions, Aspect Ratios And The ITU-R BT.601 Standard (http://forum.doom9.org/showthread.php?s=&threadid=42708), all you can do actually is to make up your own mind as to what looks best to you.

EDIT:

Also it is source dependent whether following the standard or not is correct as DVD's are mastered differently.