DVD and scaling question

[rjcarr]

I had a question about DVD and resolution. So, I can run my DVD at 1600 and there is no slowdown. But, when I run it at 1280, and 1024, I really don't notice much (if any)change in image quality.

So, my question is at what resolution does it make no difference anymore? What is the maximum possible, before quality isn't improved? What about Color Depth? Does 24/32 supported, and would it be beneficial?

I am not really looking for opinions, just if anyone knows the facts.

thanks -joe

[Himself]

I had no problems defining a 720x480 video mode, see a post I made previous on how to do it, what did you do?

[Spire]

I originally tried adding the mode (several months ago) using the <A HREF="http://www.murc.ws/Utils/PD5ResMgr.zip">PD 5 Resolution Manager</A>, but I got the error message that I described above.

Then I saw your post the other day, and tried putting in the Registry entry directly, just as you instructed. But I got the same problem.

If you have any idea why it's working for you and not for me, I'd love to hear it.

Thanks,
Spire

[Spire]

Never mind -- I figured out how to get it working. (If anyone is having the same problem I was having, let me know and I'll post instructions on how to fix it.)

However, I have to say that playing anamorphic DVDs at 720x480 looks awful, because getting it right would require two things:

1. manual adjustment of the monitor's vertical size to match the proportions (e.g. 2.35:1, or 1.85:1) of the original picture; and

2. a DVD player that can be forced to display the full anamorpic image without any scaling.

Unfortunately, even though I am able to manually adjust the monitor (which is a pain, BTW), none of the DVD players I've tried has the option to display the full anamorphic image. Because the players assume that my pixel aspect ratio is square (which it isn't, because I've tweaked the vertical size), they always end up adding on the letterbox bars, no matter what I do.

At a low vertical resolution such as the "exact" (720x480) one, the problem is compounded because 480 lines is not enough to accommodate the full image plus the letterbox bars. As a result, the image gets scaled down drastically, producing horrible stair-stepping artifacts.

Conclusion: Run at as high a resolution as your monitor can handle, and forget about trying to "tweak" things. The DVD players out there are too "smart" for their own good.

[Spire]

The resolution of an anamorphic DVD is 720x480. This is oversimplifying a little bit, but as long as your resolution is set to 720x480 or higher, you should be fine. (Actually, your vertical resolution would have to be greater than 480, to accommodate letterboxing. In real-world terms, 1024x768 is the lowest "stock" resolution that is able to display a full anamorphic image without loss in quality.) The ideal would be to use PowerDesk to define an exact 720x480 mode, but I've been unable to do so (I get an "unable to test video mode" message, or something like that.) Failing that, try defining 1440x960 (I haven't tried it yet, but it should work.). Otherwise, I would recommend that you run in the highest resolution that your monitor supports, to minimize any artifacts introduced by scaling up.

As for your color depth, it should definitely be set to 24-bit or 32-bit; it doesn't make a difference which one, since "32-bit" is actually just 24-bit that's been aligned to 32-bit boundaries (for increased speed).

[This message has been edited by Spire (edited 16 October 1999).]

[Himself]

I had to use HZTool to get it to work today after reinstalling Windows again, so that's probably the difference. Can't say I noticed any problems using 720x480x32, but I don't even have my DVD drive yet (Mon/Tues prob), I'm just going by vob files.

[dwright]

While we are on dvd resolutions, I find Matrox dvd player gives the error message "the current resolutioon and colour depth is using too much memory to create a video overlay surface and preventing dvd playback". The G400 max is set to 32 bit colour, 1280*1024, and the display is a Viewsonic PT795.
If I drop the resolution to 1024*768 with 32bit colour the Matrox dvd player works. Once the player is started I can switch back to my standard 1280*1024 and it's fine. This idicates the error message is not true. Is ther a fix for this or are you using other dvd players?
Thanks

[WereWolf]

Having the same problem...

[Himself]

I've only been using PowerDVD, the G400 one doesn't do VOB files and I have no idea where you'd tell the Cinemaster player what resolutions to use, other than the silly menu with widescreen etc.

1280x720 would be good for 16:9 playback I think, it's the right aspect ratio. It's the highest my monitor can handle without resorting to interlace as well. Gotta love the drivers for allowing such diverse monitor adjustments, reminds me of my old Amiga.

[Spire]

I can confirm that the Matrox (Cinemaster)DVD Player is hard-coded to refuse to start if the resolution is 1280x1024x32 or greater.

In fact, the G400 is able to create the requisite overlay surface all the way up to 1600x1200x32. You can verify this using the procedure dwright described (drop down to 1024x768x32, start the player, then restore to 1600x1200x32). Beyond 1600x1200, the G400 really is unable to create the overlay. (I normally run my Windows desktop at 2048x1536x32; I've tested various high resolutions for DVD playback, and anything above 1600x1200x32 is a no-go.)

I've been meaning to write Matrox and ask that they remove the hard-coded check during startup, and instead actually just try to create the overlay -- and exit if that fails. I see I'm not the only one annoyed by the hard-coded check.

Meanwhile, if I can find the time, I'll pop the player into a debugger and see if I can hack it myself to remove the check.

[Spire]

Himself,

How are you getting PowerDVD to display widescreen video without letterbox bars? Unless you can do so, using a video mode such as 1280x720 (that has the "right" aspect ratio) will not work.

I should also point out that even if you were able to do it, there is no single "right" aspect ratio anyway. DVD movies are encoded with any of at least four different ratios:

- 1.33:1 (a.k.a. pan-and-scan, or full-frame)
- 1.66:1 (not very common)
- 1.85:1 (most "wide screen" movies)
- 2.35:1 (other "wide screen" movies)

Contrary to popular belief, none of these ratios is equal to 16:9 (which actually works out to around 1.78:1). The ratio "16:9" is used simply because it's a close enough rational approximation using small integers -- similar to the way the 22/7 is used to approximate pi.

Spire

[Himself]

I'll let you know when I get the drive and try some actual DVDs, I have no idea what letterbox bars are.

[Lewpy]

I've just encountered the problem with starting the DVD player with the desktop set to 1280x1024x32bit
Has anything more been found out on this? (Apart from it being an incorrect error message anyway)

[Spire]

Currently, the only workaround is to lower the resolution to anything below 1280x1024x32, then start the player, then switch back to the original video mode (while the player is running).

Or use another player, such as PowerDVD or WinDVD.

[Zwisch]

i simply use quick desk and lower my resolution before playing a movie... this will take less than 2 sec of your time.