Blu-ray's drawbacks
HEXUS.lifestyle: So you’re saying that the disc capacity becomes irrelevant when comparing video footage between HD DVD and Blu-ray?
Jim Armour: Yes, that’s exactly it. HD DVD uses AVC, VC-1 and MPEG-2 just as Blu-ray does. It’s interesting to note that movies released on Blu-ray are all pretty much using MPEG-2 while movies on out on HD DVD are using VC1 or AVC, which offer better compression for minimal percieved quality reduction.
HEXUS.lifestyle: But in just raw data storage, Blu-ray is going to be better as it holds more data.
Jim Armour: Looking at the numbers on a bit of paper, you’d think so, but what you need to do is look at the Blu-ray discs and players first, before you make a decision. Let’s go back to the disc construction for a second. HD DVD uses a sandwich method which helps to combat disc warping. Blu-ray doesn’t. It uses a single plastic substrate layer, then adds on the recording material and then top it all off with a very hard Zircon layer. This means that when the disc expands to get hot, it will warp downwards as that Zircon layer isn’t going to budge.
HEXUS.lifestyle: But that’s a uniform direction of warping? Surely as long as you’re ready for it, it won’t make any difference?
Jim Armour: You’d think so, wouldn’t you? But now we have to go back to the lens. Blu-ray uses a 0.85 Numerical Aperture and, with their recording layer just 0.1mm below the disc surface, they’ve got to get the lens very close to the disc surface to be able to focus it tightly enough to give them a 25GB storage capacity. So now you’ve got a Blu-ray lens sitting somewhere between 0.1 and 0.3 millimetres from a disc coated with a substance almost as tough as diamond which, when it warps, can only warp downwards, towards the lens. Guess what happens when you run Zircon over glass at 2000rpm? Sure, your data will be safe but you’re going to need a new Blu-ray lens.
HEXUS.lifestyle: So the Blu-ray system has a built in flaw that could mean you get through Blu-ray players quicker than you do discs?
Jim Armour: It would appear so, yes. The other thing to remember is that Blu-ray discs are very expensive to produce when compared to HD DVD discs, mostly because of the construction methods needed to place the recording layer at the optimum distance from the lens so they can get 25GB of storage space. HD DVD takes a more sensible and robust route, chosen from a combination of factors – disc warping, disc durability, focal point of the laser etc. Plus, the use of better Codecs mean that HD DVD doesn’t even need as much storage space as Blu-ray to achieve the same high-quality video. The lower disc production costs reflect this, too.
HEXUS.lifestyle: So in summing up, HD DVD uses a more durable system of disc construction and player technology, coupled with decent Codecs to allow the same amount of high-definition video footage as a larger capacity Blu-ray disc can provide?
Jim Armour: Yes, that’s it absolutely. Don’t forget that we believe HD DVD will also give better performance over the long term due to having far better tolerances for errors than Blu-ray. Not just reading errors on the disc itself, but mechanical errors from the player, too. We don’t run our lenses as close to the disc so there’s less likelihood of a crash between the two. And if that happens, there’s less chance of the lens coming off worse with HD DVD.
HEXUS.lifestyle: If this lens-crashing is an issue, how do you see that impacting upon the PS3? After all, the PS3 is a games console that is more than likely going to be used by younger people who’ll probably knock it or move it whilst the disc is running and we all know about the Xbox 360 and the problems it had with being moved whilst a disc was spinning in the drive.
Jim Armour: That’s the thing, who can say? To be honest, I’d expect any drive or disc to fail in some way if it was being rattled about whilst trying to run and the Xbox 360 is a prime example. I think the lesson here is that the Xbox 360 was the first time people had encountered the issue. Tolerances on the PS2 were greater than on the Xbox 360 which is why we never saw any problems. And you don’t see people having trouble with a dedicated DVD player or a PC mounted DVD drive as you don’t tend to move these about. But it’ll be interesting to see how the PS3 is treated by the public when in use and to see what errors are thrown up by the Blu-ray drives. As I said, the tolerances in the Blu-ray system unlike HD DVD, don’t leave much room for ‘user error’.
HEXUS.lifestyle: Speaking of the Xbox 360, Toshiba are making the HD DVD drive for it aren’t they?
Jim Armour: Yes, that’s right, it’s an add-on part that connects via USB.
HEXUS.lifestyle: Are there any plans for a version of the Xbox 360 with the HD DVD drive built in?
Jim Armour: Not that I know of but it’s feasible. Don’t forget that HD DVD, unlike Blu-ray, is region-free, which would fit in nicely with Microsoft’s region-free games policy but no, there’s no plans that I know of.
HEXUS.lifestyle: Jim, thanks very much for the chat.
Jim Armour: My pleasure.
