Does (screen) size matter?

May 30, 2009 9:09 PM

Why do movies (.avi files) look better when viewed using a DVD player than on a computer screen?

Video files (.avi), especially lower-medium resolution videos, might look a bit pixellated when viewed on my computer (20" iMac). I'm assuming that that's due to the resolution/size of the video. But when I burn the same video(s) to a DVD (data DVD, same .avi format) and view them on the TV screen, they look extremely clear. Great quality, no blurring or pixellation, even though my TV screen is much larger than the iMac.

How does this work? Shouldn't it be the other way around, seeing as the TV screen is larger than the iMac screen?

posted by murtagh to technology (19 comments total)

Do you sit further away when you watch on TV?
posted by furiousxgeorge at 9:12 PM on May 30

It also depends on what video player you're using. Try using VLC and see if it makes a difference.
posted by sonic meat machine at 9:13 PM on May 30

Not really. I don't like sitting too close to the screen when I'm watching movies, so regardless of whether I'm watching something on TV or on the computer, it's usually about the same distance from the screen.
posted by murtagh at 9:15 PM on May 30

Tube TV? It's just blurrier in general, which covers up a lot of sins. Similar to why broadcast SD TV often looks awful on a HDTV, but fine on a standard TV.
posted by smackfu at 9:16 PM on May 30

I use VLC player to view videos. And it's a flat screen 30" LCD TV.
posted by murtagh at 9:18 PM on May 30

I've even gone close to the TV screen to see if it was a distance thing, but that wasn't the case. Has no one else experienced this?
posted by murtagh at 9:21 PM on May 30

If they're both LCDs, then there are really only two main variables:

1) The quality of the scaler. A lot of software scalers use methods that look bad because at computer display resolutions, it can be very computational intensive to use the fancier ones. Some examples. Your DVD player or TV may have hardware dedicated to this that just does a better job.

2) The color calibration of the display. Displays that are calibrated darker tend to hide sins better. Especially in areas of dark color that tend to get very nasty stair-step compression artifacts.
posted by smackfu at 9:28 PM on May 30 [1 favorite]

Is this a standard, non-HDTV television?
If so, aren't old-school TVs like 720x480 while your 20" iMac is more like 1680x1050?
So the AVI file, which is probably 624x352, has to stretch a lot more (like 4x as big) to play full-screen on your iMac—leading a lower quality image (akin to enlarging a JPG photo too large)?
posted by blueberry at 9:39 PM on May 30

Pretty sure blueberry has it. People keep the resolutions on their computer monitors higher than standard def television screens. It's not the size, it's the resolution.
posted by Precision at 9:42 PM on May 30

Seconding the resolution effect. I've noticed this too. When I play a relatively low quality avi on my TV, it looks pretty OK, but when I play that same avi on my computer, it looks terrible.

I'm not sure you can tell (you can on a Windows or Linux PC, but I've never used an external monitor for a Mac before) but when you set the output for the TV or whatever, it's usually never higher than 1024x768. In fact, a lot of TV's resolutions are much lower.
posted by Geppp at 10:34 PM on May 30

blueberry, Precision, and Geppp: the poster says it's a 30" LCD, so it's probably running at HD resolution. smackfu's more on the right track. Also, TVs generally are brighter and have higher contrast ratios than computer screens.
posted by zsazsa at 10:52 PM on May 30

blueberry, Precision, and Geppp: the poster says it's a 30" LCD, so it's probably running at HD resolution
Yeah, that's why I was asking if it was a normal (old) TV, as I hadn't seen any mention of HD...

But still, isn't an HD TV 1280x720?
Thus, on the HDTV the AVI file would only need to go from 624x352 to 1280x720 (basically 4 times the size)
as opposed to on the iMac where it would have to go from 624x352 all the way up to 1680x1050 (which is closer to 8 times the size)—hence the more-degraded image?
posted by blueberry at 11:09 PM on May 30

That's possible, although the TV could be running at 1080p, which would actually be higher than the monitor res (1920x1080).
posted by JauntyFedora at 12:30 AM on May 31

Well yeah, in that case, it would be weird that it looked better on the LCD than on the iMac. I guess I figured that if he had a 1080p TV, like the old joke, he would've mentioned it.

murtagh, can you add a comment to tell us the resolution of your LCD television?
posted by blueberry at 12:49 AM on May 31

I see the same thing. Videos I download or rip look better when played via Vista Media Center on my 360 than watching them on my laptop. I have every reason to believe it's related to the resolution of my TV (720p LCD) vs. the resolution of my laptop. If I let the videos play at native size on my laptop they look great in their tiny windows.
posted by fireoyster at 2:06 AM on May 31

I'm not sure what the TV's resolution is, but I think it's non-HDTV. Definitely don't think it's 1080p. I guess the difference is due to the difference in the screen resolutions of the TV and iMac. Size isn't relevant here. smackfu's comment makes sense too.

Thanks all :)
posted by murtagh at 3:30 AM on May 31

Don't Macs still have a different gamma?
posted by Pronoiac at 7:32 AM on May 31

And doesn't NTSC tend to make the bottom 5-10% of brightness black & something similar for white? It seems like those are often prime areas for artifacts.
posted by Pronoiac at 7:40 AM on May 31

I would definitely second the recommendation to check out the display calibration and particularly the gamma setting.

When I first got my Mac mini, I noticed that DVDs or h264 videos had a lot of artifacting in dark areas that I wouldn't see on other displays. Turned out that the default gamma setting was not right for my type of monitor.

Of course the iMac has a built-in display, but I'd still check the setting based on what your eyes actually see.
posted by dixie flatline at 10:06 AM on May 31