Aspect ratio/resize question...

[mh2360]

I have an AVI file (640x352) that I want to resize to DVD (720x576, Anamorphic). According to the guide "Determining Aspect Ratios and Resolutions" by DJRumpy, I should divide the width by the height to get the AVI's aspect ratio and resize to the nearest of the commonly used ones (1.77, 1.85, 2.35 etc...). When I do this, the aspect ratio is 1.818, the nearest is 1.85:1, which looks fine, but when I use FitCD to resize, it resizes to 1.77:1 which looks ok too. So who's right?

[SeeingMole]

I would have simply resized it to 720x352 and add black bars on top and bottom so the total resolution would be 720x576 aspect 4:3.

This will keep the original aspect ratio from the AVI file.

The original AVI file is only 640x352 and there's no point whatsoever to resize it to 720x576 16:9 anamorphic.

[thor300]

I dont agree with Mole, i would resize to 720x576 anamorphic. Thats probably the aspect ratio of the source the AVI file was made from, so your dvd could end up closer to the original than the AVI.

[SeeingMole]

What would the point of using anamorphic resolution?

You certainly won't gain any quality from it. In fact, you'll lose quality.

Besides, there's no way to know the real original aspect ratio of the DVD the AVI file was based on. You can never be sure if the person who made the AVI did resize correctly or not.

[thor300]

Anamorphic is the preferred choice for playback on 16:9 TV, many widescreen TVs cant handle movies in 4:3 with black borders so well, some old models not at all. Im not about to calculate this, but it sounds like 352 with added borders to 576 would not fit any aspect ratio, it would fill less than 60% of the vertical lines, doesnt sound quite right to me. The picture would end up squeezed.

[SeeingMole]

Yeah, I was mistaken. I was thinking in NTSC world, where the DVD resolution would be 720x480, which no conversion is necessary.

But in PAL world, the height of the AVI needs to be stretched slightly.

Here's the calculation I believe is correct:

For anamorphic:

1024 / 640 x 352 = 563.2

Resize AVI to 720x564, then add 12 pixels black on top and bottom so it'll get 720x576.

For 4:3:

768 / 640 x 352 = 422.4

Resize AVI to 720x422, then add 77 pixels black on top and bottom so it'll get 720x576.

[FulciLives]

My calculations indicate a resize from 640x352 to:

For a 4:3 WS PAL DVD ---> 704x416 with 8 pixels on the right and left and 80 pixels on the top and bottom to make it 720x576 overall.

For a 16x9 WS PAL DVD ---> 704x560 with 8 pixels on the top/bottom/right/left which will make it 720x576 overall.

But hey I could be wrong

- John "FulciLives" Coleman