[Blade47167]

2x Blu-ray Drive (72Mbps(9MB/s))
Single Layer (2x CLV) - Constant Linear Velocity (Same speed across entire disk)
Double Layer - Couldn't find any data but no games have been released on a double layer yet.

Entire Blu-ray Disk is read at 9MB/s.

12x DVD-Rom Drive SL (9.25MB/S-15.85MB/s(AVG ~8x(10.57MB/s) DL (4.36MB/s-10.57MB/s(AVG ~6x(7.93MB/s)
SL(DVD-5) 12x Max (5-12x Full CAV) - Constant Angular Velocity (Speed Varies from edge to edge)
DL(DVD-9) 8x Max (3.3-8x Full CAV) - Constant Angular Velocity (Speed Varies from edge to edge)

SL DVD is 1.57MB/s > SL Blu-ray
DL DVD is 1.07MB/s < SL Blu-ray

Majority of 360 games are on DVD-9.

Sources:
Hitachi 12x DVD-Rom Faq (Page 2)
http://www.hitachi.us/supportingdocs...ead%20speed%22
What is DVD?
http://www.videohelp.com/dvd
Blu-ray.com Blu-ray FAQ
http://www.blu-ray.com/faq/
Wikipedia - Constant Linear Velocity
http://en.wikipedia.org/wiki/Constant_linear_velocity
Wikipedia - Constant Angular Velocity
http://en.wikipedia.org/wiki/Constant_angular_velocity

So anyway I did some research and I really just want to know if there is an truth to this or do I have it all wrong.

[-tkf-]

I checked up on severeal DVD Drive reviews and i found that in average the DVD Drives even in SL mode had a problem matching the constant speed from the Blu-Ray.

The Developer on the 360 will have to place their content carefully or just go for the low speed.

[Jesus2006]

These numbers are correct.

There are however still games on single layer DVDs on the 360, but i'm pretty sure those will be very few in the future (as games grow larger and larger on those discs).

[inefficient]

The 360's that come with a Hitachi DVD drive apparently use the "GDR-3120L" model.

The PDF you have is for the GD-7500. Are we sure the performance is similar? Because otherwise the performance of DL discs seems so poor that devs might just be better off using 2 SL discs.

From their website it does seem like the GD-7500 line is the "latest" version and the GD-3xxx line has been discontinued for retail. So it does seem unlikely the 360 drive would perform any better than the GD-7500. But still I'm just saying the paper does not match the HW.

[Mmmkay]

I'm not too sure about these numbers. Each layer on a 360 disc has 3.4GB of usable space, where this is positioned on the physical disc and how the data is arranged in the space will both have an impact on average read speeds. It has also yet to be adequately evidenced in my opinion that the 360 suffers from lower performance on the second layer. Not only are the drives not (or at best variants of) commercially available drives, but things like read speed are governed by firmware not model number. These numbers (for the first layer) are also somewhat contradicted by Fredrik Lonn of Avalanche (Just Cause), who claims that in lieu of seek times, a safe estimate for read speed should be 10MB/s.

http://www.gamasutra.com/features/20.../lonn_01.shtml

Some consoles only have a DVD for reading data. How fast we can read data depends on data layout and the quality of the media. Every time we switch layers to read from, it will cost us about 100 ms. In practice, you want all streamed data on a single layer and use the second layer for in-game movies or other data that is not used frequently. Each seek will cost us about 100 ms, and a safe estimate for sustained data rate is 10 MB/s.

Which brings me to my next point of contention, these figures are idealistic in that they require sequential data. They do not take into account seek times, which are crucial in sustaining data throughput. What a Blu-ray drive (if it does genuinely operate in CLV for games) offers in consistency it loses out on seek times.

[Rangers]

Then why have several devs stated 360 drive is faster?

I dont have the links but I know I have seen it stated a couple times.

Also yeah, a CLV has slower seek times. In fact, the throughput of a 12X DVD and a 5400 RPM drive is similar, the only great advantage of the HDD is in seek times.

[Cheezdoodles]

Your also forgetting that game discs are mastered. The files your loading the most will be on the outer rim, to get maximum speed. The averages listed here, would only be correct if we loaded a full dvd9, 1 time per file. But thats not happening in real life, your loading some data more often than other data.

[DJ12]

In an ideal world that would be the case, but how many devs really spend much thought on file distribution?

Some games on PS2 were shockingly bad and the early 360 games I had, the majority of them were constantly "seeking" after a short bit of loading.

[Todd33]

I can't say how the two compare in load times on average (Motorstorm is bad though), but the noise generated is a huge difference. I'd love the option for a low RPM mode on the 360, I can live with longer loads so I can hear my games (play at night).

[Tap In]

Originally Posted by Todd33

I can't say how the two compare in load times on average (Motorstorm is bad though), but the noise generated is a huge difference. I'd love the option for a low RPM mode on the 360, I can live with longer loads so I can hear my games (play at night).

headphones

I need my game sounds to rattle my ears

[infinity4]

Originally Posted by Tap In

headphones

I need my game sounds to rattle my ears

what about headsets which i am sure most of 360 owners use here

[cthellis42]

Originally Posted by -tkf-

I checked up on severeal DVD Drive reviews and i found that in average the DVD Drives even in SL mode had a problem matching the constant speed from the Blu-Ray.

The Developer on the 360 will have to place their content carefully or just go for the low speed.

You have any links for that? I like real-world sampling, and sadly one gets damn few examples of it.

[Todd33]

Originally Posted by Tap In

headphones

I need my game sounds to rattle my ears

Ya, I do need a pair for my receiver. I wonder if my PC USB ones would work in the 360? Though I play a lot of my 360 games co-op with a phone headset on.

[betan]

People who assume constant read and seek times for BDs are forgetting Resistance has a lot of garbage data on disk.
I also remember reading that Insomniac guys burned lots of disks to get optimum access time and in order to do the tests more quickly they removed PAL videos from the game.

[Blade47167]

I knew about the seek times. I believe thats why the Oblivion game has duplicated data to help improve seek times. But once the data is found the game tends to load faster than the 360 version.

Also alot of it is put on the outer edge of the disk yes but thats still only 1.5mb/s faster if my numbers are right. And for just how much of the outer edge I'm not sure.

So your saying that the 360 DL disks are limited to 3.4GB per layer? I didn't know that I thought they were full DVD-9s. Perhaps they make it this way for a reason since the inner most part is so slow. That would make the data start about 1/4th of the way into the disk right?

I just looked up the Gears of War Image size and it comes in at 6.4GB. I'm assuming alot of that is texture data. But how much of it is actually on enough of the outer edge to actually go faster?.

I know the unreal engine using streaming so would a constant speed be more beneficial?

[Darkon]

Originally Posted by betan

People who assume constant read and seek times for BDs are forgetting Resistance has a lot of garbage data on disk.
I also remember reading that Insomniac guys burned lots of disks to get optimum access time and in order to do the tests more quickly they removed PAL videos from the game.

No, 420MB per region

[betan]

Originally Posted by Darkon

No, 420MB per region

I assume your objection to my use of a relative term stems from the early padding reports which claimed most of the data was garbage. It has nothing to do with what I wrote, and even half a gigabyte is a lot of data for me (admittedly though I thought it was around two).

That said, I cannot help but wonder though what you mean by "per region"
Is padding region locked now? What does region even mean?

[Phil]

Originally Posted by Mmmkay

Which brings me to my next point of contention, these figures are idealistic in that they require sequential data. They do not take into account seek times, which are crucial in sustaining data throughput. What a Blu-ray drive (if it does genuinely operate in CLV for games) offers in consistency it loses out on seek times.

I'm not sure I fully agree. Comparing identical cases, one can assume that identical content on both disks would cover a smaller area on the Blu-Ray disk compared to on DVD. That would imply that seek times would be at worst comparable, at best better on BluRay.

I.e.: You have a game that fills the entire DVD (single layer) - it would fill less than a fifth of the physical area on a Bluray disk, which ultimately means the laser has to travel less area to fetch data across the used space.

In ideal situations, the additional space on Blu-Ray could be used to arrange data across the disk to improve seek times.

[Mmmkay]

Originally Posted by Darkon

No, 420MB per region

>.<
32MB spacing each FMV. That's all.

Originally Posted by Phil

I'm not sure I fully agree. Comparing identical cases, one can assume that identical content on both disks would cover a smaller area on the Blu-Ray disk compared to on DVD. That would imply that seek times would be at worst comparable, at best better on BluRay.

I.e.: You have a game that fills the entire DVD (single layer) - it would fill less than a fifth of the physical area on a Bluray disk, which ultimately means the laser has to travel less area to fetch data across the used space.

In ideal situations, the additional space on Blu-Ray could be used to arrange data across the disk to improve seek times.

Yeah, I think you're right. It's something I hadn't considered. The metric for determining a seek time will probably be calculated relative to the entire disc surface. So while Blu-ray may have a general slower seek time, an indentical case comparison between a DVD-9 and BD-ROM would probably give a more favourable figure. It's an interesting scenario I would like to see benchmarked.

[Blade47167]

Originally Posted by Mmmkay

Yeah, I think you're right. It's something I hadn't considered. The metric for determining a seek time will probably be calculated relative to the entire disc surface. So while Blu-ray may have a general slower seek time, an indentical case comparison between a DVD-9 and BD-ROM would probably give a more favourable figure. It's an interesting scenario I would like to see benchmarked.

I would also liked to see it benchmarked. The first thing I remember reading was how the Blu-ray was inferior to the 360's DVD drive but from these facts thats just doesn't appear to be so. Especially if all developers get to the point were games are streamed like Lair.

[-tkf-]

Originally Posted by cthellis42

You have any links for that? I like real-world sampling, and sadly one gets damn few examples of it.

I have a few, sadly 12 x speed is pretty old in the DVD world, but here is a few examples of DVD speed:

16x speed drives, averages 12x
http://www.cdrinfo.com/Sections/Revi...11566&PageId=3
Notice how bad the DL performance is.

Older reviews without DL perfomance:
http://www.cdrinfo.com/Sections/Revi...=6176&PageId=4
http://www.cdrinfo.com/Sections/Revi...=6078&PageId=4

Etc etc, as i mentioned i have seen 12x speed drives hardly making 8xspeed on average.

DVD Burners with different read speeds, the fastest at 16x averages just above 9.
http://www.anandtech.com/storage/sho...spx?i=2224&p=9

With only 3.5GB (is that really true, i find it hard to belive) on each layer i guess the 8xspeed should be secure, those developers wanting the full speed must have to limit themselves quit heavily?

[-tkf-]

Originally Posted by Blade47167

I would also liked to see it benchmarked. The first thing I remember reading was how the Blu-ray was inferior to the 360's DVD drive but from these facts thats just doesn't appear to be so. Especially if all developers get to the point were games are streamed like Lair.

Where did you read it was inferior?

[Shifty Geezer]

Originally Posted by Mmmkay

So while Blu-ray may have a general slower seek time...

Do we know why BRD has lower reported seek times? Is it merely a matter of averages of tracking larger amounts of data as Phil's raised? Or does the hardware need to work slower to be accurate enough? Given denser tracks, the seek times should be shorter on the same head-motors, as the head can cover a larger amount of data in the same amount of movement.

[woundingchaney]

I believe that most are pointing to this article when speaking on dev. statements about drive speed and seek times of the platforms.

http://www.joystiq.com/2007/01/17/ps...blivion-delay/


I was under the impression that the concept of storing significantly more data over the same space is usually associated with seek times, as well as the head itself not moving as fast (afaik). The use of redundant data would of course improve seek times, this would also partially explain why cross platform titles having the same content have more data on BR disks. There is several statements regarding "slow" seek times and BR although Im not sure the issue has ever been fully explained. Could it be an issue with latency??
- been looking for an explanation to "slow" BR seek times for an hour I give up (obviously need to sharpen my surfing abilities).


Min - Max 12x dvd speeds and 1x - 12x BR

http://www.gamespot.com/pages/profil...9&user=skektek - warning old article

Mastering disks should give comparable speed performances for data on the outer ring (which holds the larger amount of data in circumfrence) for the larger/necessary files although of course one can expect slower speeds as nearing the center of the disk. (which makes standard average speed tests misleading given the scenario)


I honestly have no idea what amount a 360 disk can hold per side but reports range from 7-8 gig total this would be interesting to know.

[Blade47167]

Originally Posted by -tkf-

Where did you read it was inferior?

Well what I thought I was reading at first were in reality user based opinions were they had no idea what they were talking about. There was one an article on Gamespot but it was also a user posted opinion.

I guess the Oblivion thing would be the only one but I know understand that it was due to seek times.