# Why 720x480 for DVD?

Discussion in 'Archived Threads 2001-2004' started by John_Berger, Oct 30, 2002.

1. ### John_Berger Cinematographer

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This is only marginally related to my previous thread about 480p, so I'm going to just create a new thread.

I was wondering why 720x480 was selected as the resolution for DVD. It seems to be a very awkward resolution.

Assuming 480 lines as the base numeric (NTSC obviously), a standard TV (4:3) would be a resolution of 640x480. Obviously 640x480 is a very common computer resolution, so a resolution of 640x480 would have made sense.

Now enters the widescreen TV at 16:9 (1.78:1). One would think that the 720x480 resolution would be meant for widescreen TVs; however, a 16:9 AR with a 480 line base would actually yield an expected resolution of 853x480.

Upon some further mathematical calculations, 720x480 turns out to be an aspect ratio of 1.5:1, which is not even a half-way point between 1.33:1 and 1.78:1.

So, the resolution of 720x480 seems to be a very, very awkward resolution to use as the NTSC DVD standard. Does anyone have some insight as to why this resolution was selected?

2. ### Jeff Kleist Executive Producer

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It's not selected, it's pre-existing NTSC standard

The additional 80 lines are the overscan area, 40 on each side

3. ### Bill Slack Supporting Actor

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Like Jeff said, it's the maximum resolution NTSC can allow. And it's also the resolution used for widescreen enchanced discs (but the pixels are no longer square.)

4. ### Vince Maskeeper Producer

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Jeff, you've potsted this twice now, and sorry but it's not correct.
-V

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