Pixel Aspect Ratio

[Steve Roberts]

Old Media 100s use 640×480.
New ones use 720×486.
Avid Meridian uses 720×486.
Decklink uses 720×486.

The practical answer is: you use whatever your hardware dictates, or whatever your editor’s hardware dictates.

… unless you want to go shopping around for an editor who uses 640×480, you really have no choice. Look to the end of the graphic-to-editor workflow: that’s the format you use.

For editors, the non-square thing isn’t an issue, since their gear compensates. It’s only an issue with motion graphics, really, and an issue easily accommodated in AE by working in 720×540, 648×486, 720×534 or … 720×486 (or 480) with Pixel Aspect Ratio compensation on. That’s what I do.

Why did those vendors choose that 720×486 resolution? Because it’s the SMPTE standard, I suppose. Why did they pick those numbers? I read the answer to that once, but forgot it, of course. Pretty technical stuff.

Steve

[David Frisk]

So basically I could create something in After Effects with simple circles and stuff at 640×480, put it on a DVD, and it would be proportionally correct on the TV and all as though I had used 720×480 non-square?

[Yussef Cole]

This ties in with an issue I’m having trouble with:

Is 16:9 (or anamorphic) In Final Cut the same aspect ratio and screen size as AE’s 720 by 480 DV Widescreen setting? Because when I export a clip from AE into FCP and change its settings to anamorphic I feel like the movie clip is stretched a bit.

Any one know what’s going on?

Thanks,
Yussef

[Ben G unguren]

I still do things the old-fashioned way (I think it’s old-fashioned, at any rate — but makes the most sense to me). I build everything with square pixels, and then resize my animation (by nesting it in a non-square, properly sized composition, and pressing command+opt+f to fit it to the comp’s size) before rendering. The only thing you have to know is the numbers. Here’s a few:

NTSC DV:
Build it with square pixels: 640×480 OR 720×534
Render it with non-square (D1/DV 0.9) pixels: 720×480

NTSC D1:
Build it with square pixels: 648×486 OR 720×540
Render it with non-square (D1/DV 0.9) pixels: 720×486

Widescreen (16:9)
Build it with square pixels: 864×486 (or anything else with a 16:9 ratio!)
Render it with non-square (D1/DV 0.9) pixels: 720×486 (for D1) OR 720×480 (for DV)

Where there are two options in the build section, the first one should be used if you are using footage with fields, because you won’t have to do any vertical stretching to resize things, which can cause nasty problems.

If you build a 16:9 animation at 864×486 and then render it out in a DV or D1 comp (make sure you do the comand+option+f thing) you can be pretty dang confident that the squished footage has the proper dimensions.

For me, building with square pixels makes sense because my computer DISPLAYS square pixels. It also helps me to remember that there is some aspect ratio converting going on. Keeps my brain working. Sort of.

-ben

[Steve Roberts]

The big unknown in your question is “put it on a DVD”.

You need to compress your 640×480 movie to MPEG-2 before you author (and burn) the DVD, and MPEG-2 only works in 720×480 non-square. So you can make a 720×480 movie in AE, then use Compressor (or whatever) to make the MPEG-2, or use Compressor (or whatever) to scale the 640×480 movie to 720×480 when you compress to MPEG-2.

Either way, the DVD Authoring app needs to be given a 720×480 (non-square pix) movie, compressed to MPEG-2.

Hope that helps,
Steve

[Switchcase]

“Why does everyone still use 720×480?”

Because they have to make sure that their work is compatible with the lowest common denominator. There are a lot of people around the world with crappy TVs that are only going to display the old standards. Nobody wants to have Wal-Mart send back 100,000 copies of a movie because Goober and Gomer can’t get it to play on their good old Zenith.

[David Frisk]

Okay, I got ya now. I didn’t realise DVD had to be at 720×480. I guess more or less I was just wondering if I could somehow project my comp on a TV (not necessarily through DVD), if 640×480 would give the exact same result as 720×480 non-square…but I assume it would.

Anyway, thanks for the replies everyone. I appreciate it.

[Steve Roberts]

I’m just picturing “Goober and Gomer” watching TV together .. 🙂

Oh wait … it’s the same guy ….

[Yussef Cole]

So which will look more natural on a tv, dv or d1?

[Steve Roberts]

DV is D1 with some pixels lopped off the top and bottom.

“Natural” is not really a useful word. If you’re talking about high quality, those six pixels are not relevant. You should be concerned with the codec that you use if you’re concerned about quality.

If you want high quality graphics to DVD, render out of AE to the Animation codec, then use Compressor or a similar app to compress your video to MPEG-2. DV is not high quality, because the codec is not high quality. It’s a compromise. If you’re on PC, you probably have to feed an uncompressed AVI to the app which creates the MPEG-2.

I think this is a theoretical discussion, so I’ll sign off. If anyone has a specific project in mind with specific hardware issues, I’ll sign back on.

Steve