# What if DVDs were the size of LDs?

Discussion in 'DVD Video' started by Anonymous Joe, Jan 14, 2004.

1. ### Anonymous JoeGuest

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.

Anonymous Joe, Jan 14, 2004

2. ### DROGuest

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.

DRO, Jan 14, 2004

3. ### Steve(JazzHunter)Guest

On Wed, 14 Jan 2004 03:04:30 GMT, DRO <>
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 .

Steve(JazzHunter), Jan 14, 2004
4. ### Bill VermillionGuest

In article <>,
DRO <> 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, Jan 14, 2004
5. ### Bill VermillionGuest

In article <lK1Nb.46405\$nt4.80661@attbi_s51>,
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.

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

Bill Vermillion, Jan 14, 2004
6. ### Monte CastlemanGuest

>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

Monte Castleman, Jan 14, 2004
7. ### LASERandDVDfanGuest

>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

LASERandDVDfan, Jan 14, 2004
8. ### Michael RogersGuest

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.

Michael Rogers, Jan 14, 2004
9. ### Grand InquisitorGuest

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

Grand Inquisitor, Jan 14, 2004
10. ### Monte CastlemanGuest

>***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

Monte Castleman, Jan 14, 2004
11. ### Monte CastlemanGuest

>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.

I think that the basic idea of owning physical copies of media may go
away. Note the popularity of MP3 players, where you pay a buck to
download a song of the internet, rather than go out and buy a CD single.
Already my digital cable provider has something they call "i-control",
which combines the ease of obtaining pay-per-view with the viewing
flexability and user controls of traditional video rental.

As much as we laugh at DivX, it may have just been ahead of it's time
and used the wrong delivery method. What if we applied the DivX model to
video on demand, where you could pay \$4.00 for 24 hours or \$20 for an
unlimited time? Although it's nice to hold pretty CD and DVD cases,
ultimately they are shiny coasters except for the content.
>

--

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

Monte Castleman, Jan 14, 2004
12. ### Anonymous JoeGuest

"Grand Inquisitor" <> wrote in message
news:RqdNb.319\$...
> 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

This summer, there should be recordable DVD+R discs that hold 8.5GB (real
GB). That what I was referring to. Guess I forgot that not all discs are
burned

It is better to speak of something that doesnt exist and try to relate it to
something that does (ie, DVD quality), than to speak of something that
doesnt exist and compare it to something else that doesnt exist.

That is to say, how much average bitrate would an HD-DVD need? Would it be
using DTS, AC3, PCM? MPEG-4, MPEG-2? Would it's resolution be 1920x1080 or
would it use an anamorphic mode, like 1620x1080? All crucial things when
deciding what the bitrate should be used for HD.

However, if they just max the rate out at 9.8mbps CBR, making the least
compressed disc possible,in that case about 800 minutes can be put on a
single layer disc, or about 1550 minutes on a dual layer disc. That is
13h20m single layer, 25h50m for dual layer.....

Anonymous Joe, Jan 14, 2004
13. ### Steve(JazzHunter)Guest

On Wed, 14 Jan 2004 09:59:23 -0600, Monte Castleman
<> wrote:

>>***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.

Columbia-Tristar is a distributor, not a pressing plant. He was
naming the pressing plants that had problems. Columbia-tristar discs
were pressed by various plants, mostly American Pioneer I think.

. Steve .

Steve(JazzHunter), Jan 14, 2004
14. ### Rich ClarkGuest

How fast would a CLV DVD be spinning by the time the laser reached the
outside circumference, if it were 12" in diameter?

RichC

Rich Clark, Jan 14, 2004
15. ### jayembeeGuest

Monte Castleman <> wrote:

>> 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 DADC USA.

>
> I've heard that Columbia-Tristar discs were prone to rot too.

Reinhart was specifying pressing plants, not releasing labels.
Columbia-TriStar's rot problem was because they used the Sony
DADC USA plant, colloquially known as "The Rot Factory", almost
exclusively (since CTS and DADC were both Sony-owned).

> The only disc I've lost out of the 35 I have is Jumanji.

Unless your name is Kraig McGann, and every possible problem
you can have with a laserdisc gets labelled as "laser rot",
the incidence of rot is, from anecdotal evidence, about 1-2%.

I've had about 2000 LDs pass through my collection, and had
no more than a dozen that showed signs of rot. Now part of
that was due to the fact that I had a relatively small number
of DADC-pressed titles in my collection, but of the ~65 I had
(since I started noting pressing plant info), *none* of them
showed signs of rot.

-- jayembee

jayembee, Jan 14, 2004
16. ### Anonymous JoeGuest

"Rich Clark" <> wrote in message
newsNgNb.5291\$...
> How fast would a CLV DVD be spinning by the time the laser reached the
> outside circumference, if it were 12" in diameter?
>
> RichC

Well, C=?d, and if you compare the two you'll find that the two ? cancel
out, so it would be spinning 5/12ths as fast as it does now.

So....how fast is a 5" DVD spinning when it reaches the edge of the disc?

Anonymous Joe, Jan 14, 2004
17. ### Isaac KuoGuest

(LASERandDVDfan) wrote in message news:<>...

>First, CDs do not use glue. They don't need it because there
>aren't very many, if any, double-sided CDs.

There aren't any double-sided CDs. There CAN'T be any double-sided
CDs. This is because the exact thickness of the disc and depth
of the data layer are standardized, with the data layer on the far
side of the disc. If data layers were on both sides of the disc,
they'd block each other so neither could be read.

This contrasts with DVD standards, which allowed for different depths
for the data layer(s).

Isaac Kuo

Isaac Kuo, Jan 14, 2004
18. ### Mike DavisGuest

"Grand Inquisitor" <> wrote in message
news:RqdNb.319\$...
> 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

Hey Grande', I'll talk about it.
That standard has already been decided, but here's the rub;
The DVD Forum accepted the Toshiba and NEC proposal for AOD (Advanced
Optical Disc) way back in November. The problem is that it uses a
conventional laser and only holds about 15-20 GB's with super aggressive
compression. The Sony/Everybody else but Toshiba/NEC camp members of the
steering committee refused to vote, and the motion carried to accept the
T/NEC standard. HERE'S THE SUPER RUB- IT DOES NOT ADDRESS RECORDABLE HD-DVD!
You read that right. The motion picture industry just loves the T/NEC
proposal because it doesn't allow any form of recording. To be fair though,
there is still another vote to decide that format, with no real name let's
just call it HD-R This could well shape up to another vhs/beta war type of
thing where the accepted playback format would be AOD, then Sony and the
rest of the world would just go ahead and release their recordable discs.The
world wonders....
The Sony/Matshushita/Royal Dutch Phillips recordable format (known as
the Blu-Ray Disc Founder Group) allows a higher bit-rate in addition to the
most glaring difference; a caddy for the disc (not required for normal DVD
playback) that essentially requires you to by a new player. I for one don't
think that's a major issue, heck, you had to buy a new player to upgrade
from VHS to DVD, now once again from DVD to Sony's vision of HD-R. Works for
me.
All the best, Mike

Mike Davis, Jan 14, 2004
19. ### LASERandDVDfanGuest

>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.

Columbia Tri-Star software for North American consumption is almost always made
by Sony DADC USA. There are some discs made by Sony in Austria and in Japan,
though, and these discs are far superior in quality to those produced in the
USA. - Reinhart

LASERandDVDfan, Jan 14, 2004
20. ### LASERandDVDfanGuest

>There aren't any double-sided CDs.

I was specifying that "there aren't very many, if any" in terms of double-sided
CDs because I simply wasn't sure.

Rather than make a statement of fact on something I didn't know, I elected to
take an open stance, although more biased towards the notion of double-sided,
not dual-layer mind you which only exists in the realm of CD-compatible SACD
discs with the CD layer closer to the surface of the irridescent side than the
SACD layer, CDs never been made for the reasons you specified plus the fact
that I've never seen such a disc myself. - Reinhart

LASERandDVDfan, Jan 14, 2004