Velocity Reviews > What if DVDs were the size of LDs?

# What if DVDs were the size of LDs?

Anonymous Joe
Guest
Posts: n/a

 01-14-2004
Doing some math, calculating the area of a DVD's surface based on the fact
there is a 4.4cm diameter in the center that is unrecordable, and there is
0.2cm on each side that is unrecordable and that they are 12cm in diameter,
and assuming those unrecordable areas were to remain constant in a 12" disc
(LD or LP size), I found that the recordable area of a 5" disc is 40.715
square cm. If these discs were to be 12" they would contain a whopping
517.94 square cm of recordable area.

Just assuming that if these 40.715 cm² can hold 4.7GB, then it would stand
to reason that 517.94 cm² can hold 59.8GB. But, since 4.7GB isnt real GB
but rather 4.38GB, then this 59.8GB is really 55.7GB. Alright, so 55.7GB on
1 layer. If its dual layer, like the 8.5GB discs that could be released
this summer, then you have 108GB.

How much can 55.7GB hold?

Well, I found out how big the main movie was on each of 15 random discs I
have and compared that to the length of the movie. The result, there are
approximatley 37.61MB used for each minute of movie. In a 55.7GB disc, it
would then stand to reason that if the quality is kept like it is now, then
1517 minutes could fit on a disc. That's a little more than 25 hours. Now,
if the discs have 2 layers, then they hold about 2940 minutes, or 49 hours.

Wow, I'm so glad that nobody has made a movie that needs a disc that large.
Although, if you had one you could put all of the LOTR movies on there. Or
all the Godfathers. Or any other trilogy you can think of. Maybe James
Bond would need one of them dual layer discs, though How about series?
You could fit the first 2 seasons of the Sopranos on 1 single layer disc.
Or you can fit all 4 seasons on 1 dual layer disc. How many Simpsons
episodes is that? Wow, thats a lot, 133 episodes or so. I believe that
works out to 6 seasons, since the first year was short.

Nah, I much prefer the convenience of 5" discs, though. If it wasnt for the
CD, our DVDs could have been based on LDs, though, since that was the only
other optical media and came well before CD.

Then again, the covers for these discs would have some really nice artwork.
That is one thing I liked about real albums...much more space for artwork.

DRO
Guest
Posts: n/a

 01-14-2004

Two words "Laser Rot". When disks get that big, they seem to become unstable
after a certain amount of time. The same materials, and Glue seemed to be used
for CD's and DVD's and Laser Discs, but only laser disc has a significant level
of laser rot. Some day we will have solid state cartridge type system for movies
with just a Memory chip inside them and that will be great leap forward that the
video industry, and the chip industry needs.

Steve(JazzHunter)
Guest
Posts: n/a

 01-14-2004
On Wed, 14 Jan 2004 03:04:30 GMT, DRO <(E-Mail Removed)>
wrote:

>
>
> Two words "Laser Rot". When disks get that big, they seem to become unstable
>after a certain amount of time. The same materials, and Glue seemed to be used
>for CD's and DVD's and Laser Discs, but only laser disc has a significant level
>of laser rot. Some day we will have solid state cartridge type system for movies
>with just a Memory chip inside them and that will be great leap forward that the
>video industry, and the chip industry needs.

I don't want to get into the laser rot thing again. It's NOT endemic
to the format or size, just mistakes in how the things were pressed..
And DVD is showing some failure also. I would say that dual-layer 12"
discs are probably impractical. I have 1400 lasediscs, 25 or so show
some rot or speckling or snowiness.

I just wanted to mention that a digital laserdisc format HAS been
toyed-with based on a slightly compressed version of the professional
D2 tape format. This was in the late 80's A disc would hold 6 hours
on one side with six channels of DISCRETE audio. However this was
more for pro use than for consumers, and Mpeg2 came along allowing a
smaller CD-sized disc so the idea was never developed.

. Steve .

Bill Vermillion
Guest
Posts: n/a

 01-14-2004
In article <(E-Mail Removed)>,
DRO <(E-Mail Removed)> wrote:
>

> Two words "Laser Rot". When disks get that big, they seem
>to become unstable after a certain amount of time. The same
>materials, and Glue seemed to be used for CD's and DVD's and
>Laser Discs, but only laser disc has a significant level of laser
>rot.

LD's were laminated while CD's and DVDs are manufactured as one
piece. I have some 8" LDs that were made just like CDs and
required a spacer to make them play on a standard player.

Two different technologies and the CDs learned from the LDs.

As to the first poster wondering about how much would be on them,
when Sony was first working with what became CD technology they had
a 12" form factor. They never though of the CD size as the world
had been using 12" disks for so long. They saw no market for an
audio disk that would play hours and hours on a side, and it was
not until they teamed up with Philips, that Philips suggested the
small size. Then it was just deciding how big to make it, and they
picked one long complete classical work as the target of 74
mintues, and the current size was born.

I remember seeing CD's first introduced at an AES show in NYC.
There were 50 titles announced to be released, and there were a few
at the show. And they were sweating to see if they could get 5%
of the market before DAT came out. Since the world was so
accustomed to tape, and media that you could record upon, they
figured that if they didn't have 5% market penetration by the time
DAT came out the format would go away.

What with pending legislatin in congress to put a tax on DAT tapes
because that would be distributed to record companies [some things
never change], and some manufacturing troubles, by the time DAT
came out CD was on it's way to being king. It's been an
interesting 20+ years watching this grow.

>Some day we will have solid state cartridge type system for
>movies with just a Memory chip inside them and that will be great
>leap forward that the video industry, and the chip industry
>needs.

There are other technologies that may replace solid state chips for
this type of presentation. Ideally you want something that can be
manufactured and used immediately, and not something that has to be
programmed. Think along the lines of holographic storage in
transparent media, and that is a more logical future scenario.

--
Bill Vermillion - bv @ wjv . com

Bill Vermillion
Guest
Posts: n/a

 01-14-2004
In article <lK1Nb.46405\$nt4.80661@attbi_s51>,
Anonymous Joe <(E-Mail Removed)> wrote:
>Doing some math, calculating the area of a DVD's surface based on the fact
>there is a 4.4cm diameter in the center that is unrecordable, and there is
>0.2cm on each side that is unrecordable and that they are 12cm in diameter,
>and assuming those unrecordable areas were to remain constant in a 12" disc
>(LD or LP size), I found that the recordable area of a 5" disc is 40.715
>square cm. If these discs were to be 12" they would contain a whopping
>517.94 square cm of recordable area.

>Just assuming that if these 40.715 cm² can hold 4.7GB, then it
>would stand to reason that 517.94 cm² can hold 59.8GB. But, since
>4.7GB isnt real GB but rather 4.38GB, then this 59.8GB is really
>55.7GB. Alright, so 55.7GB on 1 layer. If its dual layer, like
>the 8.5GB discs that could be released this summer, then you have
>108GB.

The new DVD standard - when they decide what format it will be -
will have 40GB on the current sized disks.

As to needing this much - HDTV will require that much to be able to
put an HDTV movie on the current form factor, even with the MPEG-4
compression which is close to 4 times more efficient than MPEG-2.

--
Bill Vermillion - bv @ wjv . com

Monte Castleman
Guest
Posts: n/a

 01-14-2004
>How much can 55.7GB hold?
>
>Well, I found out how big the main movie was on each of 15 random discs I
>have and compared that to the length of the movie. The result, there are
>approximatley 37.61MB used for each minute of movie. In a 55.7GB disc, it
>would then stand to reason that if the quality is kept like it is now, then
>1517 minutes could fit on a disc. That's a little more than 25 hours. Now,
>if the discs have 2 layers, then they hold about 2940 minutes, or 49 hours.

Or they could increase the bit rate to eliminate compression artifacts and
provide 7 channels of PCM audio.
---

Monte Castleman, <<Spamfilter in Use>>
Bloomington, MN to email, remove the "q" from my address

LASERandDVDfan
Guest
Posts: n/a

 01-14-2004
>Two words "Laser Rot". When disks get that big, they seem to become unstable
>after a certain amount of time.

Not necessarily.

>The same materials, and Glue seemed to be used
>for CD's and DVD's and Laser Discs, but only laser disc has a significant
>level
>of laser rot.

First, CDs do not use glue. They don't need it because there aren't very many,
if any, double-sided CDs. LDs must use glue in order to bond two disc "halves"
together to make one dual-sided disc. If a mistake is ever made in the process
of joining the two disc halves together or if the glue itself is not good, then
you will have laser rot on an LD. This is generally what causes it to happen
to a LaserDisc if everything else is done right in manufacturing and if the
user is not abusive with storage and handling of discs.

Secondly, the plastics used are not the same. While CDs and DVDs use
polycarbonate, LaserDiscs use acrylic. These plastics do have distinct
characteristics which sets them apart.

Third, you can have a CD or a DVD that may have a peculiar condition, usually
from a fault in manufacturing but also from user abuse, which would promote
oxidation of the reflective substrate (which is what laser rot is essentially),
but the problem can sometimes go unnoticed throughtout the media's usable life
thanks to error correction used in the binary coding.
LaserDiscs, on the other hand, are an analogue medium, so it doesn't have the
benefit of error correction. As a result, manufacturing quality is much more
critical with LaserDisc than it is with CDs and DVDs. Manufacturing flaws that
would normally not cause any headaches with CDs and DVDs would cause big
problems with LDs. With most cases of LD laser rot, the problem gradually
shows up as the disc sits in storage. As mentioned before, this occurs mainly
due to contamination of some sort between the two disc halves. Sometimes, the
glue might be tainted. Other times, air or even particulates may have become
trapped between the disc halves. The contamination can penetrate through the
lacquer layer and chemically attack the aluminum substrate, altering its
reflective qualities.

***BUT***, contrary to popular notion, laser rot with LDs is actually a fairly
rare occurance, especially when you take into consideration that there are more
playable discs than there are rotted discs. Also, if discs have already aged
to the point where if rotting didn't happen already, it will never happen at
all unless someone immerses the disc into a pool of water or other things you
aren't supposed to do to a LaserDisc. The problems with chronic rot are mainly
isolated to discs produced in the early 1980s, A LOT of discs produced by
Technidisc, some discs produced by 3M, and late 1990s discs produced by Sony

>Some day we will have solid state cartridge type system for movies
>with just a Memory chip inside them and that will be great leap forward that
>the
>video industry, and the chip industry needs.

Right now, such a system would be too cost-prohibitive. Mask ROMs are not only
expensive to manufacture, but also require that manufacturing orders be placed
months before the scheduled release date.

Optical discs are advantageous because they can be made rather quickly and with
less costs than magnetic cassette tapes, at least in the case of DVD and CD
discs.

As for the original poster's idea, the reason why two discs were glued together
to make one with LDs was to make the disc rigid and more resistant to warping.
To make an LD-sized DVD, you have to find a way to make the disc more rigid to
resist warping. Also, the data storage capacity for a 12 inch disc may
actually be greater than the original poster's claim, especially if the disc
was written in CLV. - Reinhart

Michael Rogers
Guest
Posts: n/a

 01-14-2004
or you can just have less running time and FULL TILT BOOGIE SUPER MEGA
bit rates.

Anonymous Joe wrote:
>
> Doing some math, calculating the area of a DVD's surface based on the fact
> there is a 4.4cm diameter in the center that is unrecordable, and there is
> 0.2cm on each side that is unrecordable and that they are 12cm in diameter,
> and assuming those unrecordable areas were to remain constant in a 12" disc
> (LD or LP size), I found that the recordable area of a 5" disc is 40.715
> square cm. If these discs were to be 12" they would contain a whopping
> 517.94 square cm of recordable area.
>
> Just assuming that if these 40.715 cm² can hold 4.7GB, then it would stand
> to reason that 517.94 cm² can hold 59.8GB. But, since 4.7GB isnt real GB
> but rather 4.38GB, then this 59.8GB is really 55.7GB. Alright, so 55.7GB on
> 1 layer. If its dual layer, like the 8.5GB discs that could be released
> this summer, then you have 108GB.
>
> How much can 55.7GB hold?
>
> Well, I found out how big the main movie was on each of 15 random discs I
> have and compared that to the length of the movie. The result, there are
> approximatley 37.61MB used for each minute of movie. In a 55.7GB disc, it
> would then stand to reason that if the quality is kept like it is now, then
> 1517 minutes could fit on a disc. That's a little more than 25 hours. Now,
> if the discs have 2 layers, then they hold about 2940 minutes, or 49 hours.
>
> Wow, I'm so glad that nobody has made a movie that needs a disc that large.
> Although, if you had one you could put all of the LOTR movies on there. Or
> all the Godfathers. Or any other trilogy you can think of. Maybe James
> Bond would need one of them dual layer discs, though How about series?
> You could fit the first 2 seasons of the Sopranos on 1 single layer disc.
> Or you can fit all 4 seasons on 1 dual layer disc. How many Simpsons
> episodes is that? Wow, thats a lot, 133 episodes or so. I believe that
> works out to 6 seasons, since the first year was short.
>
> Nah, I much prefer the convenience of 5" discs, though. If it wasnt for the
> CD, our DVDs could have been based on LDs, though, since that was the only
> other optical media and came well before CD.
>
> Then again, the covers for these discs would have some really nice artwork.
> That is one thing I liked about real albums...much more space for artwork.

Grand Inquisitor
Guest
Posts: n/a

 01-14-2004
Anonymous Joe wrote:
> Just assuming that if these 40.715 cm² can hold 4.7GB, then it would stand
> to reason that 517.94 cm² can hold 59.8GB. But, since 4.7GB isnt real GB
> but rather 4.38GB, then this 59.8GB is really 55.7GB. Alright, so 55.7GB on
> 1 layer. If its dual layer, like the 8.5GB discs that could be released
> this summer, then you have 108GB.
>

*This* summer? Dual-layered discs have been around since the early days.

Besides, I thought you were going to talk about the HD potential of such
a disc.

--
"Get rid of the Range Rover. You are not responsible for patrolling
Australia's Dingo Barrier Fence, nor do you work the Savannah, capturing
and tagging wildebeests."
--Michael J. Nelson

Grand Inquisitor
http://www.dvdprofiler.com/mycollection.asp?alias=Oost

Monte Castleman
Guest
Posts: n/a

 01-14-2004
>***BUT***, contrary to popular notion, laser rot with LDs is actually a
fairly
>rare occurance, especially when you take into consideration that there are

more
>playable discs than there are rotted discs. Also, if discs have already aged
>to the point where if rotting didn't happen already, it will never happen at
>all unless someone immerses the disc into a pool of water or other things you
>aren't supposed to do to a LaserDisc. The problems with chronic rot are

mainly
>isolated to discs produced in the early 1980s, A LOT of discs produced by
>Technidisc, some discs produced by 3M, and late 1990s discs produced by Sony

I've heard that Columbia-Tristar discs were prone to rot too. The only disc
I've lost out of the 35 I have is Jumanji.

--

Monte Castleman, <<Spamfilter in Use>>
Bloomington, MN to email, remove the "q" from my address