Video sizing: conceptual Q's

jpstory wrote on 8/19/2009, 8:29 AM
Hi all. I make a lot of 'video slideshows' -- videos made without video footage, only with jpegs and an audio track -- as part of my work. I have always set them up with default NTSC settings (720x480, non-square pixels), but I'm realizing that almost everyone I make these for plays them on a computer, not on a DVD player/TV.

When I thought about changing my approach, I realized I don't really understand some of the fundamental concepts about video/pixel sizes. So I had a few conceptual/practical questions:

1) If I set the projects up with bigger dimensions, say 1440x960, would the slideshows look better when they're played back on a computer, esp. one with a big screen?

2) I couldn't make a DVD that would play in a TV-attached DVD player with these bigger settings, right? But could I make one where the user could insert the DVD in a computer DVD player and double-click to get the full-sized video?

3) Do video players, like Windows Media Player and Quicktime, do some sort of 'translation' when they see a NTSC DVD inserted? It seems like the DVDs made with nonsquare pixels look okay when played back on a computer through these players.

4) If I make a bigger dimension video and the user plays it back on a computer attached to a projector, I'll loose the advantage of the bigger size, right? Since projectors typically don't have more than 1024 px on the horizontal axis?

5) What size/pixel shape would you recommend using?

Any thoughts on any of these questions would be much appreciated. Thanks!
JP

Comments

PerroneFord wrote on 8/19/2009, 8:56 AM
Some good questions, but not all have clear answers. It is somewhat dependent on the source material.

1. This is greatly dependent on the source photos. If the source photos are larger than 1440x960 (odd choice of sizes there) then they would probably look better on a computer monitor

2. No, DVD is necessarily 720x480 in the US. Can't go bigger than that. "DVD" is kind of misleading. There is DVD media (which is just a blank silver disk of a certain size) and then there is DVD video format which is VERY specific in terms of size, what compression is used, etc. A DVD formatted disk will play exactly the same no matter what kind of device you put it in. However, you can put any kind of files on a blank DVD. However, that kind of DVD will NOT play if you just stick it in your DVD player a the house.

3. NTSC DVDs carry instructions on how to correctly interpret the video contained within. So these programs respect that.

4. Many modern projectors can play back material beyond 1024. Everyone in our oiffice does.

5. I recommend using the proper pixel shape for your intended delivery format. That is the important thing.
rmack350 wrote on 8/19/2009, 9:02 AM
1) You could set up a project to have a custom frame size for use on a computer. You should probably use a PAR of 1.0 in your project settings to avoid confusing the software player. The movie would probably look better. Why not try it this and test it out?

2) You cannot make a DVD for playback on a set top DVD player using these bigger settings. However, you could burn a Data DVD for use on a computer. DVD Architect wouldn't be useful for this so if you want some sort of interface you'd have to use some other authoring tool. Most likely you just want the movie to play on any computer without forcing the end user to download a new player.

3) Software DVD players usually adjust the movie's Pixel Aspect Ratio for your computer screen. Sometimes they mess this up but usually they get it right.

4)If you make a video that is bigger than your display device's resolution then you'll probably end up scaling the movie back down to fill the screen during playback. This'd be true whether it's a projector or a desktop display.

5) Pixel aspect ratio (sampling rate) should be 1.0 if you intend the video to be played on a computer.

There are all sorts of caveats to all of this so I think you'd be better off doing some test renders and trying things out for yourself.

Rob Mack
jpstory wrote on 8/19/2009, 9:16 AM
Thanks! This helps. The photos I have are generally quite high-rez. Just a follow-up regarding question 2:

When I buy a stack of blank DVD- discs, are they DVD formatted? So say I exported the final project as bigger resolution AVI or WMV (not as an mpeg-2) and burned to a DVD just by dragging the file onto the disc in Windows and burning? My thought was that in that case, I'd not be 'making a DVD' but rather putting a file on a storage media that just happens to be a DVD. So the video wouldn't be crunched down to 720x480 for playback.

Have I got that right?

JP
jpstory wrote on 8/19/2009, 9:25 AM
Looks like Rob answered my question: I can use any old DVD as a data DVD and put a bigger dimension video on it.

But I hadn't thought about playing the file back on the user's computer -- it wouldn't work if the user just inserted the DVD and double-clicked on the file?

I'll have to do some more fiddling around... In the end, maybe it's easiest to just stick with 720x480. Doesn't look bad, just not as sharp as it could.
PerroneFord wrote on 8/19/2009, 9:35 AM
It would work with a double-click if the user had Windows Media Player (if that's how you encoded) Or had quicktime with the same codec you used to compress it.

I'd say try to go HD if you can. 1920 x 1080 square pixel.
Terry Esslinger wrote on 8/19/2009, 10:26 AM
Not to jump in and confuse things but it is my understanding that you can burn BR (HD) on standard DVD media (but only 20 minutes)
PerroneFord wrote on 8/19/2009, 10:31 AM
Maybe 5 minutes, maybe an hour. Depends on bit rate selected and what size DVD media you use. But just because you can burn it, doesn't man your BluRay player can read it. Most don't. A few will.
jpstory wrote on 8/19/2009, 11:30 AM
So sounds like you could burn an HD video onto a standard DVD (the projects I make are never longer than 5 minutes, so they should fit) and have it autoplay on a computer.

That sounds more elegant than the user needing to double click, as they would with a data DVD...