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When a downgrade is an upgrade

Posted on January 1st, 2007 by Cray-Z5200.
Categories: everything else, tech.

Hello people! The monster is finally in the house, after weeks of procrastinating and uninspired thinking. The final push of inspiration came from none other than Real Life, which gave me such a serious dose of “You can’t handle the truth” that I simply had to write about it.

What on earth am I talking about? It’s my computer and the LCD TV I’ve hooked it up to.

I got the TV (an Amoi 32″, uses an LG panel so I try my best to ignore the name) as a well meaning present from my dad, who was trying to thwart my plans to hook up my PC to the living room TV. I suspect it was more for himself than for me or my mum, really; he knows all too well that the cost of making peace offerings is a mere triviality next to the fury of a mother deprived of quality time with Oprah and friends.

In any case, for the longest time now I’ve hooked up my PC to the TV with a DVI to HDMI cable. For the uninitiated, a DVI port is the white on that appears on most graphics cards nowadays; the end of the cable looks like this. HDMI is the new standard port for high definition broadcasts, which virtually all cable stations are ballyhooing about; it looks like this. Sort of USB-ish, if you ask me. Both DVI and HDMI are quite similar since they both transmit video signals digitally, but since HDMI is made for TV, it’s been designed to carry sound signals to the TV as well.

Here’s where it gets interesting. Normal desktop resolutions don’t display too well with a HDMI connection. In fact, they look horrible. Most resolutions are prone to overscan, where the borders of the image your device is sending to the screen are cut off, or underscan, where the image doesnt fill the screen completely. On computers, this isn’t too nice when you’re fumbling around blindly for the Start button or the dock.

Until recently, I thought it was just part and parcel of living with HDTVs. My graphics card drivers (Nvidia 7800GTX) did a good job of scaling down the screen resolution to fit the screen nicely with a little fiddling, so I carried on like the wayward son I was. Standard resolutions I set like 1280×720 would be scaled down to 1200×676, and I had to tweak game files in order for them to play with such odd numbers. Still, I was getting an image that filled up the whole screen, and I was happy.

Oh the silliness. Recently, at a friend’s house, I noticed that a 17 incher was displaying video with much less blockiness. And it wasn’t just the video; many of my photos that appeared blocky on my screen appeared perfect on hers. All this time I’d chalked it up to the fact that my TV, being bigger, would reveal imperfections of the source material previously unseen on smaller screens, but now I wasn’t so sure.

After some digging on the great Internets, I realised that the HDMI interface may not be the PC’s perfect loverboy after all.

It’s quite simple; HDMI input only takes in certain resolutions. Very specific ones, for that matter; the standard HD resolutions are 1280×720 and 1920×1080. Any other resolution in between, the TV will take either of the two resolutions it knows and scale up or down accordingly. This scaling process isn’t perfect, resulting in overscan or underscan, AND the distortion of images and video on the screen. This is the evil that caused all that blockiness on otherwise normal photos and videos!

So you ask, why can’t my TV take 1280×720 and display it nicely? Isn’t it one of the standard resolutions that a HDTV recognises?
That’s because my TV’s one of the new breed who think having a bunch more of pixels will make them extremely cool and happening. That’s right; my TV has 1366×768 native pixels. That’s supposed to give a true 16:9 aspect ratio, which is what widescreen is all about. As a result though, the scaling process is quite different, and 1280×720 from a PC input has problems.

So if I can’t use HDMI to display my pixels nicely, let’s see what other inputs my TV has…

Oh noes! Only VGA!

VGA’s an analog standard, which means my graphics card has to convert the video signal to analog, and when the signal gets to the TV, it has to be converted back to a digital format before it can be displayed on the screen. Sounds (key word: SOUNDS) time consuming, unnecessary and less high fidelity when it comes to image quality,which is why I used the HDMI input in the first place. Still, VGA would display the image on my screen pixel for pixel, instead of doing all that scaling I didn’t need, right? So I bit back my pride, took a VGA cable, affixed a DVI adapter to one end, and hooked the PC and TV up.

OMGBBQ11one1!

Almost all resolutions I tried displayed perfectly and fit the full screen, although some (including my beloved 1280×720) needed to be nudged a little to the left through the drivers. The so called decrease in quality due to the analog connection was negligible, honestly; edges and fonts might be a teeny bit more blurry, but nothing to call mommy for. And I can clearly see that any blockiness in videos and photos is due to the source material, not because some stupid scaling process made the image blockier than it already was.
All in all, it would be best if you have a DVI plug on your tv, so that there’s no need for any digi-analog-digi conversion. But if your choices are between HDMI and VGA… pick the ‘worse’ one. Trust me on this.

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