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M-Disc DVD questions

Mussels said:
The article i linked to is fascinating since you can visually indentify the dyes used in various CD-R types
View attachment 288411
I recall preferring some that had a black dye (Perhaps it was just a really dark blue), all the generic silver ones i used for storage back then decayed in 10-15 years or so



Since a lot of posts got removed for people being people, heres a screencap from that link that explains a lot of the confusion on this topic - the dye used can give you garbage that rots away in days in sunlight, or that lasts centuries
Printed discs should in theory last forever if they arent damaged physically, although they can and do get brittle over time so the high RPM's might shatter them when they get used by future archeologists

View attachment 288412
Click to expand...

I'm surprised that read-only DVD & Bluray's expected life is so short. I've always thought the pressed discs would hold up better than burned dye discs. If that table is accurate, I suspect a lot of people are going to be very disappointed when they go for a movie nostalgia trip in a few years.
 
Mussels said:
and these devices didnt have ECC, they assumed perfection.
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I forgot the details but CDs do have some ECC.
650 MB data CD = 780 MB audio CD because data CDs have some redundant data to correct errors.
And even audio CD data is EFM encoded (eight-to-fourteen modulation, 14 bits used to encode 8 bits). That gives it some resilience against single-bit errors. Of course, long scratches on the surface are not single bit errors.

sLowEnd said:
I'm surprised that read-only DVD & Bluray's expected life is so short. I've always thought the pressed discs would hold up better than burned dye discs. If that table is accurate, I suspect a lot of people are going to be very disappointed when they go for a movie nostalgia trip in a few years.
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No matter if pressed or burned, I've seen damaged data layer in some old discs. It's always near the edge. Apparently, the glue that holds plastic layers together deteriorates and lets some air in, causing slow oxidation. Data near the edge becomes unreadable, the rest is ok.
 
Wirko said:
I forgot the details but CDs do have some ECC.
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This is true. There is a certain level of error correction built into the CD/DVD/BD standards. However, it is fairly basic...
Wirko said:
And even audio CD data is EFM encoded (eight-to-fourteen modulation, 14 bits used to encode 8 bits). That gives it some resilience against single-bit errors. Of course, long scratches on the surface are not single bit errors.
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...as you've described. While this seems good(and it is), it is not perfect. Other forms of error correction can and have been employed with optical media.
Wirko said:
No matter if pressed or burned, I've seen damaged data layer in some old discs. It's always near the edge.
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That is generally an old LaserDisc problem popularly known as "laser-rot". CD, DVD and BluRay do not(and generally will not) suffer from the same problem as the conditions that lead to laser-rot were engineered out of the equation through changes in manufacturing and materials formulation.
 
Did the millennium go bankrupt? the contact on their website no longer works for me to ask for mdisc dvd technical information
 
MDiscWebSite-ContactUs.jpg
Seems to be working for me.
 
gamer87fla said:
What expectancy logevity years M-Disc DVD data in my conditions 35C 60-73% RH?
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No one can answer this.
How long are you going to live, to the second?

gamer87fla said:
I'm trying to send them a query site nor work mensage
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Sorry but that doesn't make sense, was that translated from another language?


The questions you've asked here, no one can know - it's not like they've had 500 years to try these discs out and be sure exactly how long they last to the minute.
 
gamer87fla said:
now I found this PDF of millenniata old site herself my case is 117 years?
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Note the little word "mean" below the table. Overly simplified, it means that some M-discs will die 42 years from now, about half will survive for 117 years, and some will likely remain readable after 555 years.
 
Mussels said:
No one can answer this.
How long are you going to live, to the second?
Click to expand...
Mussels said:
The questions you've asked here, no one can know - it's not like they've had 500 years to try these discs out and be sure exactly how long they last to the minute.
Click to expand...
Wirko said:
Note the little word "mean" below the table. Overly simplified, it means that some M-discs will die 42 years from now, about half will survive for 117 years, and some will likely remain readable after 555 years.
Click to expand...
The "Mean" indicates a variation of +/- 10%. A lot of people seem confused by the estimates with no possible test samples as a reference. The answer for that problem is simple: Known chemistry, physics and math. We can reliably calculate the half-life of any radio-isotope for any element to a variance of less than 1/1000th of a percent. Likewise we can predict the degradation rates for chemicals we make within a certain variance. We can also calculate environmental factors into the equation.

So the estimates are reliable within the context of a certain set of factors and can be trusted so long as the proper disclosures meet with evidence based merit.
 
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