OT Why is DV 720×480?

[Steve Eisen]

https://www.adamwilt.com/DV.html Learn it all!

Steve Eisen
Eisen Video Productions
Director-At-Large
Chicago Final Cut Pro Users Group

[Graeme Nattress]

486 is not evenly divisible by 8, and the DV codec uses 8×8 blocks. You can get around this, but it would have made the codec chips more complex, and as those lines are in the overscan and never seen anyway….

Graeme

– http://www.nattress.com – Film Effects and Standards Conversion for FCP

[Scott Davis]

That begs the question. Why is SD 720×486 then?

Scott Davis

[Chris Borjis]

Does mpeg2 video use 8×8 blocks?

Is that why DVD is 480?

[Tom Wolsky]

Because if you use a pixel that has an aspect ratio of 0.9 you get a 4:3 image. Why that number of pixels? That’s what was decided in 1987 by the CCIR for broadcasters using NTSC allowing them to provide the best image in ratio to bandwidth expended.

All the best,

Tom

Author: “Final Cut Pro 5 Editing Essentials” and “Final Cut Express 2 Editing Workshop” Class on Demand “Complete Training for FCP5” and “Final Cut Express Made Easy” DVDs

[Paul Dickin]

Hi
The non-square pixel notion seems to have come about as a solution to digitally encoding NTSC or PAL formats without having to run the video tape at different linear speeds, as in Beta SP or VHS.
A standard sampling rate of 13.5MHz can be applied for both formats, each keeping its own frame-rate, if the pixels are distorted to non-square by a factor of 0.9 for NTSC and 1.1 for PAL (both figures approximate).

[Chris Poisson]

Scott,

I’d think because it was analog is one reason.