Comments on: Showing a static DVD image with minimal blurriness

Question: Showing a static DVD image with minimal blurriness

russilwvong — Sat, 23 Feb 2008 17:42:22 -0800

DVD authoring on Ubuntu: I'm trying to create a DVD showing a single static image, containing logos and text, for playback on a standard DVD player. What's the best way to avoid blurriness?

When I use dvd-slideshow, the image is a bit blurry, presumably because it's scaled down from 720x540 to 720x480 during the encoding, then scaled up again to 720x540 during playback. Is there a way to avoid this?

This is using NTSC.

By: sanka

sanka — Sat, 23 Feb 2008 17:58:30 -0800

I've always vectored the logo, blown it up to 720x480 and saved in as a PNG. Keeps it crisp. The DVD player I use at work actually seems to crop the outside 10% of the image so the black bars don't even show up.

By: russilwvong

russilwvong — Sat, 23 Feb 2008 18:16:25 -0800

What tools do you use to create the DVD from the PNG?

By: sanka

sanka — Sat, 23 Feb 2008 18:21:25 -0800

Adobe Premiere Elements. Sorry I was just offering general advice, not Linux based. If the logo isn't too colorful you could go with an indexed GIF I guess, or save the JPG at full quality and see if it's blurry there.

By: filmgeek

filmgeek — Sat, 23 Feb 2008 19:39:17 -0800

Yeah, all the stuff out there could lead to soft stills.

720x540 crunched down, will cause your image to soften (as it converts to non-square pixels vertically by going to 720x480.) This crushes field information., your vertical resolution.

Instead, design at 640 x480, and it should be stretched outwards (in non square pixels) and it should look a bit sharper (since it's horizontally scaling, which is a sample rate, based on bandwidth, not hardcoded as fields.)

By: infinitewindow

infinitewindow — Sat, 23 Feb 2008 21:46:08 -0800

filmgeek is right on the money.

By: russilwvong

russilwvong — Sat, 23 Feb 2008 23:01:03 -0800

Thanks for the tips, everyone. Here's what I'm using so far:

Use vector (Encapsulated PostScript) version of the logo, capture a bitmap at the right size, use GIMP to create a 640x480 image.

Add blank space on the left and right to make a 720x480 image, export as PPM.

Use the MJPEG tools (dvd-slideshow appears to be a wrapper) to create a one-minute MPEG2 file from the PPM, multiplexed with a silent AC3 audio file.

Use the makexml and makedvd tools provided by tovid to create the DVD structure and burn the DVD, editing the xml file to make the DVD jump back to the beginning.

During this last step, makedvd sets the aspect ratio to 16:9, causing the image to be stretched from 720x480 to 854x480. I suppose that's preferable to setting the aspect ratio to 4:3 and having the image be stretched from to 720x540. I don't suppose there's any standard way to indicate that the DVD player shouldn't stretch the image at all?

By: Malor

Malor — Sun, 24 Feb 2008 02:38:18 -0800

During this last step, makedvd sets the aspect ratio to 16:9, causing the image to be stretched from 720x480 to 854x480. I suppose that's preferable to setting the aspect ratio to 4:3 and having the image be stretched from to 720x540. I don't suppose there's any standard way to indicate that the DVD player shouldn't stretch the image at all?

From the little that I know of DVD authoring, the disc has an aspect ratio setting, and then your DVD player does the best it can to display that signal within the confines of the output resolution.

If you do what filmgeek said, and use 640x480, but do everything else the same, it sounds like it'll come out right. Horizontal scaling looks pretty good; it's not likely to cause visible damage to the image. The signal gets scaled during playback anyway, both by the DVD and by the TV. It's fundamentally being displayed by a fuzzy, imprecise analog system. It's probably not worth driving yourself nuts to get a 1% final image quality improvement.

By: russilwvong

russilwvong — Sun, 24 Feb 2008 22:31:22 -0800

Just a quick update: I tested the DVD last night (on my cheap DVD player hooked up to a consumer-grade projector), and it worked fine today (on a much larger, theater-size screen).

Thanks again, especially to filmgeek. I was pretty worried about compatibility--I didn't have access to the target DVD players to be able to test the DVD beforehand--and so I wanted to make sure the DVD conformed to the standard as much as possible. I was also really worried that any blurriness would look even worse when blown up to theater size. Knowing that converting from 720x540 to 720x480 was the problem helped a lot.