Friday, February 04, 2005

How to reveal you are an idiot - part one of a series

The other day I was in a computer shop in Tottenham Court Road, and I overheard a customer explaining things about laptop screens to a person who he was shopping with.

"This one has an LCD screen, and this one has a TFT screen. See the difference?"

It is actually true that the terms "TFT" and "LCD" mean different things.

LCD means "Liquid Crystal Display", meaning that the each pixel works by having a voltage applied across a liquid crystal element, the opacity of the element varies in accordance with the voltage, and when a light is shone through it it appears light or dark depending on the voltage. (Colour displays work by having three crystal elements per pixel, each with a different coloured filter - one red, one green, one blue).

TFT means "Thin Film Transistor", meaning that there is a transistor attached to the back of each crystal element, which controls the voltage applied to that element. TFT is synonymous with "active matrix" when applied to LCD displays. TFT screens are sharper than old kinds of passive matrix LCD screen, and as a consequence passive matrix screens are no longer available on laptops.

Now it is also possible for Thin Film Transistors to be used to control other kinds of display besides LCDs. Some people are quite optimistic about a new display technology called Optical Electroluminescence (OEL), and prototype OEL displays generally do have the pixels controlled by Thin Film Transistors.

So, it is therefore technically true that not all LCD displays are TFTs, and also that not all TFTs are LCDs, but for practical purposes the two terms are synonymous, particularly when referring to laptop screens. So the person in the computer shop was doing a fine effort at demonstrating that he did not know anything.

Thursday, February 03, 2005

Why 5.1 channel audio is good

When I was assembling my present Athlon 64 based PC, I initially couldn't get anything to appear on the screen. The motherboard would boot, the fans would spin, and then nothing would appear on the screen. (In the end, the solution was an extreme case of needing to kick myself for missing something obvious - socket 754 motherboards have a second 4 pin 12V power connector that provides power to the CPU and that needs to be plugged in in addition to the main 20 pin ATX connector, and the socket A motherboards I had previously assembled do not. And I didn't have the 12V connector connected). I am not a gamer, and as a consequence I didn't bother upgrading the graphics card, although most of the rest of the computer was new. As it happened though, bad case design had meant that I had had a little difficulty removing the graphics card from the previous machine, and I had forced it a little more than I would have liked in order to get it out. As a consequence, when the new machine did not work, I assumed that the problem was with the graphics card.

So, eager to get my new computer to start, I purchased a new graphics card. I did something I wouldn't normally do, and bought the card from my local retail park PC World, a branch of the evil Dixons group. (Okay, not actually evil, just clueless and stocked with a far too limited selection of seriously overpriced product. The description of the Vogons from The Hithhikers Guide to the Galaxy as "not actually evil, but bad-tempered, bureaucratic, officious and callous. They wouldn't even lift a finger to save their own grandmothers from the Ravenous Bugblatter Beast of Traal without orders signed in triplicate, sent in, sent back, queried, lost, found, subjected to public inquiry, lost again, and finally buried in soft peat for three months and recycled as firelighters" comes to mind, actually). I got some kind of 128Mb ATI Radeon 9600 that had been returned by somebody else for about £60 if I recall correctly.

Anyway, as I said, the graphics card turned out to not be the problem. Once I had the machine working on the original graphics card, I took the new card I had bought back to PC World in the condition they had sold it to me. Perfectly reasonably (given there was nothing wrong with the product they had sold me) they were not willing to give me a refund, but they were willing to allow me to exchange it for something else from the store. (So they perhaps weren't evil). However, the issue of the store being overpriced and badly stocked came up, and it took me a while to find anything I wanted. Eventually, I found a set of Creative 5.1 speakers for about the right right amount of money, and I bought them and took them home. Plugging them into the computer, I found two problems. Firstly, the OEM copy of Cyberlink PowerDVD that came with the DVD drive turned out to only support 2 channel audio. In order to listen to my DVDs with full six channel audio, I needed to get some extra audio codecs. (Does Windows XP media center edition come with extra audio codecs built in? Even if it does, it doesn't greatly matter because I have XP Home). Cyberlink had a variety of packages available. The cheapest including Dolby Digital 5.1 cost $20, but I went for the "every codec under the sun" package for $25 (mainly because I wanted to be able to listen to DTS soundtracks on those DVDs that have them). Okay, great.

Still, though, there was one problem. I did not bother buying a separate sound card for the PC, on the (ultimately correct) assumption that the on board 5.1 audio would be fine. The speaker system is connected to the computer via three 1/8th inch two channel audio connectors (mini-headphone jacks, basically) on the back panel. For some inexplicable reason, there are two conventions for the third connector (which handles the centre speaker and the sub-woofer) in such cases. Because the nature of these audio channels and the way they are amplified is so different, you can't simply reverse the speakers, as you could if there was any such confusion for any of the other channels. And the driver that came with the motherboard (and later versions on the VIA website) didn't allow the channels to be reversed in software. So rather than getting the dialogue out of the centre speaker (as is normal with most movies), I got a very garbled version of the dialogue out of the sub-woofer.

However, there was finally a solution. A bit of googling located a different set of drivers for the on-board audio system, which did allow me to properly reverse the audio channels. Finally I could listen to DVD soundtracks the way that god intended.

And what can I say? The audio is just beautiful. I have the full cinema soundtrack in all its surround sound, multichannel and low frequency effects glory to listen to when I am watchind DVDs on my lovely 19 inch Sony DVI display. The difference is noticeable and is immensely better than with lesser sound systems. (Many people use astonishingly crap speakers on their computers - this doesn't matter if you are only using the speakers for dignostic purposes, but if you are going to listen to music or watch movies you need better). I have a set of two channel speakers that are fine for music but not as good for movies, and I probably would have used these for the new computer if it were not for the fact that I had store credit to spent at PC World. While I am not happy that it took me as much effort as it did to get the computer to work, the end consequence was good, as it led me to buy a set of speakers that I would have bought had I known how good it would be to have them.

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