Audio CDs can survive a bit of degradation to the odd data bits here or there; the music will just skip the millisecond of missing data and your ears won’t notice. Likewise with vinyl. Data discs on the other hand have the issue that if a single data bit is lost, a whole file could be corrupted, especially if it’s a zipped file.

In addition, printed audio CDs are of a different build than CD-Rs which have been found to not be as resistant to moisture and light.

It takes more than a single bit--there are Huffman codes built into the spec, but it is certainly possible for the bits to degrade enough to render a sector or even the whole disc unreadable.

If you're serious about using optical media as archival storage, you can mitigate this by incorporating your own error correcting codes into the data storage format.

FWIW. CD-ROM has stronger FEC than CD-DA. It still won't protect you from bit rot, particularly on writable media.

https://en.wikipedia.org/wiki/CD-ROM#CD-ROM_format

CDROM bit rot is mostly the paint flaking off, but the real data is stored in the plastic. DVD should be even harder to bitrot because data is entirely inside the plastic. Burned disks are another story.

You must be joking. Try to scrape off the paint and keep the plastic, see if it works.

bitrot is paint flaking off, not someone purposefully scratching it off

It is primarily humid air diffusing through the platter and corroding the aluminum coating. The "bits" are sandwiched between two layers of plastic (one thin). The paint on the surface is irrelevant.

> I have 30 year old CDs that play as good as the first time, as well as older vinyl discs.

Mass produced CDs are produced using a different process than the one consumer CDR writers use, and they are thus a much more stable storage medium. The data-containing layer is literally formed out of metal using a kind of mold: https://en.wikipedia.org/wiki/Compact_Disc_manufacturing#Ele...

CDRs are written by altering a layer of dye with a laser, and that dye is very vulnerable to chemical breakdown: https://en.wikipedia.org/wiki/CD-R#Physical_characteristics

You can extend the lives of writable and rewritable optical media by proper storage. The key is to avoid light and heat as much as possible, to keep the dyes stable. I'm not sure about 30 years, but you can probably get 10 out of properly stored optical media. See the following advice:

>A disc should always be handled by grasping its outer edges, center hole or center hub clamping area. Avoid flexing the disc, exposing it to direct sunlight, excessive heat and/or humidity, handle it only when being used and do not eat, drink and smoke near it. Discs should be stored in jewel cases rather than sleeves as cases do not contact the discs’ surfaces and generally provide better protection again scratches, dust, light and rapid humidity changes. Once placed in their cases discs can be further protected by keeping them in a closed box, drawer or cabinet. For long-term storage and archival situations it is advisable to follow manufacturer instructions. For further information consult the international standards for preserving optical media (ISO 18925:2002, Imaging materials — optical disc media — storage practices). [0]

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[0] : http://www.osta.org/technology/cdqa12.htm

> You can extend the lives of writable and rewritable optical media by proper storage. The key is to avoid light and heat as much as possible, to keep the dyes stable. I'm not sure about 30 years, but you can probably get 10 out of properly stored optical media.

Though, if you care about longevity, it might be better to use a technology like M-DISC. It uses a different recording technology to "[burn or etch] a permanent hole in the material, rather than changing the color of a dye."

https://en.wikipedia.org/wiki/M-DISC#Materials_technology

Yep...not to mention all discs are ultimately made of plastic which is subject to environmental degradation - primarily oxidation from atmosphere and UV damage, both which can lead to yellowing/clouding of the transparent medium, and eventually brittleness and fracture.

same, but I've also seen some cheaper makes of CDRs break down after 20 years and the storage layer crack etc.

quite. the writable discs don't last nearly as long. i had a pile of writable DVDs that were unreadable 8 years later when i went back to fetch the data from them.