Downsizing help using mod16

[kkiller23]

I'm trying to encode my bluray into a NON-HD MKV file, The source res is 1920x1080. I'm using megui, i clicked the mod16 thing and i can't find a res that is 1.777 etc

My question is if i untick the mod16 and enter 768 x 432 would it still be mod16? I've used that res before with the mod16 box ticked so i'm not sure why it doesnt show up as 1.777 now in megui.

Any help would be great.

[jagabo]

My question is if i untick the mod16 and enter 768 x 432 would it still be mod16?

768 / 16 = 48
432 / 16 = 27

So yes they are both mod16. But 768 is wider than most standard definition videos. The max width is 720 for DVD, for example. Most Divx DVD players won't play Divx/Xvid files over 720 pixels wide. 704x400 is mod16 and close to 16:9. 640x360 is 16:9 but only mod8 on the vertical axis.

[kkiller23]

I have a another question. Why does one program show the bluray as 1,85:1 and the other show it 1.777? Megui is saying it's 1.777, but another says its 1.85.

[davexnet]

I have a another question. Why does one program show the bluray as 1,85:1 and the other show it 1.777? Megui is saying it's 1.777, but another says its 1.85.

Is it because the widescreen movie actually is 1.85:1 and the mysterious "other" program
is taking some letterboxing into account ?

[hello_hello]

Mod16 dimensions must be divisible by exactly 16, and unfortunately when you resize the video using MeGUI, it can only suggest the "nearest" mod16 dimensions. Even though traditionally mod16 was generally used, it's no longer important so most other software these days will suggest mod4 or mod2, enabling more exact resizing. I'm not sure why MeGUI is still stuck in the mod16 era. Maybe not enough users care.

As an example, a video with exactly 16:9 dimensions might be re-sized to standard definition using a width of 720. If there's no cropping, a height of 404 pixels is very close to 16:9. I'd probably use 704x396 as it's exactly 16:9.
Unfortunately MeGUI, which will only suggest mod16, will probably suggest something like 704x400. As a result, the picture is slightly distorted when resizing. It's not exactly anything new. Video is often resized when converting to mod16 AVIs in the same way, however.....

The problem becomes one of finding a way to calculate the best height, especially if the original video required cropping. To solve the problem, I use this calculator: http://www.mediafire.com/?09v9bldu9a6hm00

Normally I use MeGUI to open the original video and get the cropping right. I then use the calculator and enter the source video's dimensions (1920 x 1080 for Bluray), and also the amount of cropping I'm using. Usually I set the calculator to mod16 and use the slider to find the nearest mod16 dimensions (as MeGUI would) then I change it to mod2 and adjust the height individually until the aspect ratio distortion is at a minimum (sometimes cropping a couple of extra pixels gets it to 0%). Once I get the best height, I manually type it into MeGUI's resize field.

It might sound a bit "fiddly" but you'll probably get used to using the resize calculator pretty quickly. It'll also calculate DVD resizing. I'm so used to using it, it's become second nature when setting up an encode, but hopefully one day MeGUI will be able to suggest (calculate) mod2 resolutions on it's own.

I have a another question. Why does one program show the bluray as 1,85:1 and the other show it 1.777? Megui is saying it's 1.777, but another says its 1.85.

Yeah it sounds like the video uses black bars which have been cropped. MeGUI always displays the input display aspect ratio when opening video using the script creator, but if any of the video or back bars are cropped the output aspect ratio will be different. That's probably why MeGUI isn't suggesting 768 x 432 for you, because if the video is 1.85 after the black bars are removed they're no longer the best mod16 dimensions to use. I'd imagine of you select 768 as the width, ticking the "suggest mod16" box will get MeGUI to suggest something like 416 as the height.

[kkiller23]

Thank's for that tool, it's a amzing. It's a lot better then using a regular calculator