BR/HD-DVD Thread

[jvd]

Fal i can see them both wanting them in the new systems .

I would see it playing out to whats ever the cheapest they can put in

Perhaps ms will go with normal dvds if they can get a 16x drive cheaply. Perhaps an even faster one.

I dunno about sony but they may wnat to invest as much as they can into the rendering hardware and may go with a normal dvd player too

 

[nondescript]

Anyway, slightly to another topic - for people that see these formats as viable in upcoming consoles, even if you believe that basic drive price will go down enough to be reasonable - a console would need at least 4xspeed BD/HD-DVD drive... arguably more given the increase in capacity (Xenon's DVD is currently specced at 16x).
Coupled with rise in media cost, I would really like to hear some arguments that justify the economics of stuffing this in a nexgen console, because right now I can see mostly negatives (ignoring my personal greed for more space and latest and greatest shiny gadgets of course).

I largely agree with cthellis...

I think the only compelling reason to put BR in PS3 (other than geek lust) is to instantly acheive economies of scale. As I said earlier, BR has the potential to be cheaper than DVD (at least single-sided BRs). The process technologies are there, they just need the volume. PS3 could acheive acheive that volume by itself.

As for maintaining profit margins and such, I think if PS3 went for a read-only BR (perhaps using the 5/10mW SLD31 laser diode), they could avoid cannibalizing their own DVD/BR recorder sales while driving BR adoption.

As for using BR as a method to persuade consumers to hold off Xenon and wait for PS3, I dunno...how many people held off Dreamcast to wait for PS2 because of DVD?

There are plenty of reasons not to put BR in PS3 too, of course:

Does Sony really want to put yet another highly ambitious technology in the PS3? I`m sure Sony execs still remember the component shortages they had with the PS2 launch. Let`s say they launch in early 2006, starting PS3 mass production in Q3-Q4 2005. They have a little over a year to have build a BR manufacturing and supply chain, handling productions volumes of around million/month. I`m not saying it can`t be done - they could adapt their existing supply chain to do this - but it`s another element of uncertainty.

Then there`s the 4x speed Faf wants - can they develop a 4x BR-ROM drive in time, I dunno.

 

[cthellis42]

As for using BR as a method to persuade consumers to hold off Xenon and wait for PS3, I dunno...how many people held off Dreamcast to wait for PS2 because of DVD?

Dunno. It's impossible to measure, but will certainly have an impact. If Sony also has the technical edge and retains its developer and mindshare edge... there are only so much MS would be willing to let their machine slip. If the prices ended up being the same and just the tech differed (and they're only looking at buying one console for a while to come), waiting and watching would be easy. Next-gen media player + next-gen console = the good stuff! At they very least, a lot would be apt to wait and see how the Japanese launch turns out, as they'd be able to compare the gaming experience between them in likely not much waiting. (Other than the demos and leaks they'd see before anyone launched.)

Ultimately a lot more factors will weigh in, and they'll each have their own weight per individual. But I feel pretty easy in saying that--barring totally unforseen advantages of disadvantages (including delays and price variances) popping up--the choice between a next-gen media player and simple DVD would perk a number of ears.

 

[Vince]

Faf, I think a good point was raised here; did Sony cannibolize their CE DVD player sales with PS2? Did it slow down the adoption or aggregate revenue in any way at all?

It was allways my impression that Sony intends to make its profit off Blu-Ray primarily with digital content sales, not hardware. Am I wrong?

 

[PC-Engine]

A Little Physics

Quick and painless, I promise.

The three main characteristics of optical media are: wavelength, numerical aperture, and protection layer thickness. BD and HD-DVD have the same wavelength, so we can ignore that.

Disk Capacity is proportional to: (Numerical Aperture)^2/(Wavelength)^2

This is the physical limit - obviously, we need to consider ECC, file system overhead, etc... BD should theoretically allow 71% more data than HD-DVD, but that is clearly not the case. This may reflect a more conservative design.

Disk Flatness Tolerance is proportional to: (Wavelength)/(Protection Layer Thickness*(Numerical Aperture)^3)

A quick calculation shows that BD is about 160% more tolerant to disk flatness imperfections than HD-DVD.

Protection Layer Thickness Tolerance is proportional to: (Wavelength)/(Protection Layer Thickness*(Numerical Aperture)^4)

A quick calculation shows that BD is about 80% more tolerant to protection layer thickness imperfections

Blu-ray needs a uniaxial actuator to correct the spherical aberration caused by the uneven thickness of the thin .1 mm cover layer of a BRD. It also needs a glass lense.

HD-DVD doesn't need to worry about that since the standard .6mm cover layer of DVD as well as HD-DVD means HD-DVD discs are almost perfectly flat so it's kinda irrelevent. It doesn't need a glass lense.

It's like comparing a Viper with a Hayabusa. A Hayabusa doesn't need 500hp to go fast. If a HD-DVD is already 99.9% flat who cares?


Anyway regarding Xenon, I'd expect it to be able to play HD-DVDs based on red lasers through software decoding.

 

[aaaaa00]

How did you come up with these calculations?

These are (apparently) pretty standard "rule-of-thumb" metrics - so I suggest you head to your local university`s EE/Applied Physics/Materials Science/Physics library, look up Optical Storage Media, and find a book with a more theoretical approach.

They may be standard "rule of thumb" metrics, but as far as I can tell, they're not giving you the right answers.

These equations are clearly missing several things.

For one, spot focus is not the only limiting factor when determining the maximum data density.

And your relative cover layer tolerance estimates between HD DVD and BD are just plain wrong. (No there isn't going to be a web link I can point to which will give you the right information, sorry.)

 

[nondescript]

They may be standard "rule of thumb" metrics, but as far as I can tell, they're not giving you the right answers.

These equations are clearly missing several things.

For one, spot focus is not the only limiting factor when determining the maximum data density.

The key word is PROPORTIONAL - obviously there are other factors at work, from lens quality to signal processing to plastic consistency to the phase of the moon.

All I was comparing was the intrinisic performance differences between the two formats - the lens quality can improve, the DSP can be updated, the phase of the moon changes, but you can`t change the format. From the specs that have been given, I can compare their RELATIVE theoretical performance.

The system with a thinner cover layer will have better performance, unless there are other factors to counteract it. But the relation between thinner cover layer and data density holds true regardless. And since I haven`t seen any "other factors" published yet (nor have you mentioned any) I can`t make comparisons based on those other factors.

And your relative cover layer tolerance estimates between HD DVD and BD are just plain wrong. (No there isn't going to be a web link I can point to which will give you the right information, sorry.)

Um ok. Then if you don`t mind, I think I`ll stick with the Phillips presentation then.

 

[MfA]

Nintendo should put some money behind Ritek, as far as the cost of the drives is concerned nothing will be able to touch their new format. The media takes care all of the nasty stuff, all you need is a CD-ROM drive capable of running at lower RPM than usual and tracking the finer pitch. (All assuming the technology actually works of course ... the physics behind it are voodoo, it's all based on experiment.)

 

[nondescript]

Blu-ray needs a uniaxial actuator to correct the spherical aberration caused by the uneven thickness of the thin .1 mm cover layer of a BRD. It also needs a glass lense.

uniaxial actuator = thing that moves lens up and down.

Uneven thickness of the cover layer will cause aberration, I agree. But a thinner layer makes it less sensitive to thickness variation. I haven`t seen any article saying they must have a glass lens (link please?), but I wouldn`t be surprised - the higher numerical aperture requires a better lens.

HD-DVD doesn't need to worry about that since the standard .6mm cover layer of DVD as well as HD-DVD means HD-DVD discs are almost perfectly flat so it's kinda irrelevent. It doesn't need a glass lense.

Using DVD processes may not be good enough for HD-DVD. Running through the numbers for DVD, HD-DVD is half as tolerant to thickness differences and flatness differences as DVD.

I don`t understand why you think HD-DVD discs are "almost perfectly flat", while BR discs have "uneven thickness". Care to explain? I don`t know much about injection molding, but as far as I can tell, both can be made equally flat. Hamamatsu has machines that can create pieces with less than 2 micron variation ... no polishing required.

Anyway regarding Xenon, I'd expect it to be able to play HD-DVDs based on red lasers through software decoding.

Right. All the engineers working on blue laser HD-DVD-ROMs should just pack up and go home then...

 

[aaaaa00]

Um ok. Then if you don`t mind, I think I`ll stick with the Phillips presentation then.

Ok, stick with whatever you want then.

I forwarded your post to an engineer that's worked on the various optical media formats for more than a decade, has worked in the DVD Forum (and has had a part in DVD, AOD, and some part in Blu Ray), and he told me your calculations do not describe the relative differences between HD DVD and Blu Ray accurately.

I can ask for more detail if you want, but I think it's unlikely he's going to elaborate much more than this, and I really don't want to waste any more of his time.

Using DVD processes may not be good enough for HD-DVD. Running through the numbers for DVD, HD-DVD is half as tolerant to thickness differences and flatness differences as DVD.

While the fact that HD-DVD will require more precision than DVD is true, it is clear at this point that most existing DVD processes will be able to reach the required precision with only minor tweaks compared to BD.

 

[jvd]

So here is a question.

What does it take to play hd-dvds.

Can you use a standard pc dvd player as long as your hardware can decode it or do you need a new drive.


If its a new drive how much more will it cost over a standard dvd drive ?

 

[aaaaa00]

So here is a question.

What does it take to play hd-dvds.

Can you use a standard pc dvd player as long as your hardware can decode it or do you need a new drive.

If its a new drive how much more will it cost over a standard dvd drive ?

HD DVD uses a blue laser. You will need a blue laser drive, which is different from your current DVD drive, which uses a red laser. No one here knows how much such drives will cost yet, and if they did, they couldn't tell you without gettting in trouble.

There is a different proposal out there, that uses a regular DVD drive, but with VC9 (WM9) as the compression codec, that can fit HiDef movies onto regular DVDs. I'm not sure what the status of this proposal is right now. For that, on your PC, you can just use a regular DVDROM drive and have the right software installed (and enough CPU power).

 

[nondescript]

I forwarded your post to an engineer that's worked on the various optical media formats for more than a decade, has worked in the DVD Forum (and has had a part in DVD, AOD, and some part in Blu Ray), and he told me your calculations do not describe the relative differences between HD DVD and Blu Ray accurately.

Well, if your engineering-pal-with-list-of-impressive-and-scary-credentials said that, I`m not going to argue with him. Could he be so kind as to give a correct comparision between the two? If he says the percentages are off, fine - these are just rule-of-thumb calculations based on optics only, and were never meant to be precise. However, if there is something fundamentally wrong, I would like to know. I highly doubt he will deny the benefits of a thinner protective layer and higher numerical aperture, but I freely admit that might not be the whole picture.

I can ask for more detail if you want, but I think it's unlikely he's going to elaborate much more than this, and I really don't want to waste any more of his time.

There is no need for you to bother him if he doesn`t wish to be bothered - since you "clearly" understand why I`m wrong, I humbly await your enlightenment.

They may be standard "rule of thumb" metrics, but as far as I can tell, they're not giving you the right answers.

These equations are clearly missing several things.

 

[PC-Engine]

Blu-ray needs a uniaxial actuator to correct the spherical aberration caused by the uneven thickness of the thin .1 mm cover layer of a BRD. It also needs a glass lense.

uniaxial actuator = thing that moves lens up and down.

Uneven thickness of the cover layer will cause aberration, I agree. But a thinner layer makes it less sensitive to thickness variation. I haven`t seen any article saying they must have a glass lens (link please?), but I wouldn`t be surprised - the higher numerical aperture requires a better lens.

HD-DVD doesn't need to worry about that since the standard .6mm cover layer of DVD as well as HD-DVD means HD-DVD discs are almost perfectly flat so it's kinda irrelevent. It doesn't need a glass lense.

I don`t understand why you think HD-DVD discs are "almost perfectly flat", while BR discs have "uneven thickness". Care to explain? I don`t know much about injection molding, but as far as I can tell, both can be made equally flat. Hamamatsu has machines that can create pieces with less than 2 micron variation ... no polishing required.

Anyway regarding Xenon, I'd expect it to be able to play HD-DVDs based on red lasers through software decoding.

Right. All the engineers working on blue laser HD-DVD-ROMs should just pack up and go home then...

http://www.sony.net/SonyInfo/News/Press/200405/04-026E/

In the object lens, introduction of aspherical glass and hologram lens to achieve spherical aberration correction, corresponding to each wavelength enables one series of optical system to deal with 3 wavelengths.

http://www.burningbits.com/artman/publish/article_62.shtml

It adopts the double objective lens with the numerical aperture of 0.85, as well as an uniaxial actuator to correct the spherical aberration caused by the uneven thickness of the cover.

http://www.blu-raydisc-official.org/tecinfo/data/tech01.pdf

Another critical manufacturing tolerance, particularly for DVDs, is the
flatness of the disc, because the laser beam becomes distorted if the disc surface is not
perpendicular to the beam axis – a condition referred to as disc tilt. This distortion increases
as the thickness of the cover layer increases and also increases for higher numerical aperture
lenses.

Again since DVD and HD-DVD uses the same cover layer thickness with stringent flatness tolerances, tilt is not a problem. OTOH BRD needs a aspherical glass and hologram lens to achieve spherical aberration correction since it's aperture is higher.

Using DVD processes may not be good enough for HD-DVD. Running through the numbers for DVD, HD-DVD is half as tolerant to thickness differences and flatness differences as DVD.

Hamamatsu has machines that can create pieces with less than 2 micron variation ... no polishing required.

But is it being used for BRD? Regardless why are we even talking about this? HD-DVDs are being produced so any reading problems have obviously been overcome/solved...

 

[jvd]

So here is a question.

What does it take to play hd-dvds.

Can you use a standard pc dvd player as long as your hardware can decode it or do you need a new drive.

If its a new drive how much more will it cost over a standard dvd drive ?

HD DVD uses a blue laser. You will need a blue laser drive, which is different from your current DVD drive, which uses a red laser. No one here knows how much such drives will cost yet, and if they did, they couldn't tell you without gettting in trouble.

There is a different proposal out there, that uses a regular DVD drive, but with VC9 (WM9) as the compression codec, that can fit HiDef movies onto regular DVDs. I'm not sure what the status of this proposal is right now. For that, on your PC, you can just use a regular DVDROM drive and have the right software installed (and enough CPU power).

Thanks thats how they do the t2 disc then. Which looks awsome on my pc

 

[DeanoC]

Perhaps ms will go with normal dvds if they can get a 16x drive cheaply. Perhaps an even faster one.

I've heard this from a very reliable source...

There probably won't be any CD/DVD like drives that go faster than 16x and most 16x drives are proving to be 12x in practise due to extra errors generated (16x are also known for scratching disks!).

The problem at these speeds is not the drives themself but the discs. DVD discs cannot take the velocity and have a tendency to explode (yes explode) at >16x.

 

[aaaaa00]

There is no need for you to bother him if he doesn`t wish to be bothered - since you "clearly" understand why I`m wrong, I humbly await your enlightenment.

They may be standard "rule of thumb" metrics, but as far as I can tell, they're not giving you the right answers.

These equations are clearly missing several things.

Lets look at it this way using your figures and your math:

DVD uses a 650 nm laser, and uses a numerical aperture of 0.60.
HD DVD uses a 405 nm laser, and uses a numerical aperture of 0.65.

As you said, disc capacity is proportional to NA^2 / wavelength^2

So if we plug these numbers into your equation, it claims that if a single layer DVD is 4.7 GB, then an HD DVD disc can be no more than about 14.2 GB. According to you, this is the physical upper bound.

Since your own figures for HD DVD indicate the capacity for a single layer disc is 20 GB, this is clearly not the case.

If we are to accept that your equation is reasonably accurate, either the creators of DVD were incompetent enough to leave out 30% of the possible capacity of the disc (unlikely), or the HD DVD creators were somehow smart enough to get more capacity than is physically possible (really unlikely).

Therefore your calculations have to be flawed in some way. They must not be accounting for other important engineering parameters, some of which may change the assumptions made when the equation was formulated.

Hence my conclusion that something is clearly missing.

And so, IMHO, statements like this:

This is the physical limit - obviously, we need to consider ECC, file system overhead, etc... BD should theoretically allow 71% more data than HD-DVD, but that is clearly not the case. This may reflect a more conservative design.

Are quite frankly wild speculation. (Love the two significant digits of precision using something that is just "a rule of thumb". )

 

[-tkf-]

PCWorld talks Blue Laser: http://www.pcworld.com/news/article/0,aid,116265,pg,2,00.asp

Some of the stuff they write doesn't add up to what was posted here?

The DVD Forum, NEC, and Toshiba claim that HD-DVD, which increases the capacity of DVD from 4.7GB to 15GB per layer

??

 

[aaaaa00]

PCWorld talks Blue Laser: http://www.pcworld.com/news/article/0,aid,116265,pg,2,00.asp

Some of the stuff they write doesn't add up to what was posted here?

The DVD Forum, NEC, and Toshiba claim that HD-DVD, which increases the capacity of DVD from 4.7GB to 15GB per layer

??

HD DVD is 15GB for the single layer read only, 20GB for the single layer R/W.

 

[kaching]

If we are to accept that your equation is reasonably accurate, either the creators of DVD were incompetent enough to leave out 30% of the possible capacity of the disc (unlikely), or the HD DVD creators were somehow smart enough to get more capacity than is physically possible (really unlikely).

You're leaving out a more likely possibility: the DVD creators achieved acceptable capacity for the uses intended and didn't need to go further. "Good enough" for devices meant for the consumer market.

It's not like we aren't seeing the exact same thing play out with HD DVD. BRD proves that it is technically possible to put at least 25 gig/layer with currently available technologies but HD DVD opts to stop at 15 gig/layer as "good enough" balanced against the ability to capitalize on existing disc manufactuing lines and more advanced video compression techniques.