Why 848 by 480?

-Reda- · Post by **-Reda-** » Sun Jun 15, 2008 2:21 pm

Just wondering, and this may be a silly question but I've wanted an explanation for a while now. Why are all these AMV's with widescreen sources exported at 848 by 480? They "look right" but 848 by 480 is not a proper 19:9 resolution (correct me if I'm wrong). So why not export at 800 by 480, which would in fact be the closest thing you could get to actual 16:9 aspect ratio at that size?

Excuse me if this post is made out of some form of ignorance, I just wanted the actual reasoning behind this cleared up.

Mosc · Post by **Mosc** » Sun Jun 15, 2008 2:50 pm

800x480 isn't anything near 16:9. Just do the math: 480 * 16 / 9 = 2560 / 3 = 853.333[3...]. The reason people use 848x480 rather than 853x480 is that DCT based video compression methods work best when the width and height are divisible by 16. 848x480 is the closest resolution that satisfies this condition, and no one will notice the slight aspect ratio error. Does that mean 848x480 is optimal? Not at all. NTSC DVDs are 720x480 and thanks to the aspect ratio correction flag in modern containers like Matroska and MP4, it's possible keep your video at the original resolution (after cropping away the black bars, of course) and resize to the proper aspect ratio on playback.

Pwolf · Post by **Pwolf** » Sun Jun 15, 2008 2:54 pm

The proper way to do it would be to resize to 853x480 and then crop down to 848x480. I end up resizing to 848x480 anyway, heh.

Pwolf

-Reda- · Post by **-Reda-** » Sun Jun 15, 2008 2:56 pm

Very informative, thanks much ^_^

And that's why I'm not a math major lol

AaronAMV · Post by **AaronAMV** » Sun Jun 15, 2008 4:58 pm

And from what I know, is that it is for more of DVD rips then downloaded anime.