[d332]

But that's not my goal. I'd like to be able to observe every grove, the physical encoding of data, and see if I could implement decoding from scratch. First problem is though that I don't know how to get a microscopic image of the disc.

[ssl-3]

You don't need a microscopic image of a disc to do that; a two-dimensional photograph is of essentially no advantage here.

All you need is the unmolested data from that disc. The data is arranged on a singular spiral groove starting from the center and slowly winding its way towards the outside.

The data is completely linear: It begins at the beginning, and continues to the very end without interruption. This is all akin to (although opposite of) how a single-track vinyl record is physically laid out. The entire CD -- whatever it contains -- is just a continuous string of pits and lands.

And to observe that string as it appears on a real disc, all you need to get started is a regular old-school CD player and some appropriate data acquisition gear, and maybe an oscilloscope to help figure out what you're looking at.

The optics and basic motor controls are already solved problems, and it doesn't even have to be particularly fast data acquisition gear by today's standards to record what is happening.

[AkBKukU]

Look into the Domesday Duplicator project for Laserdiscs as an example of how what ssl-3 is talking about can be done using a high sample rate input. That exact process is possible and with enough storage and processing power can be used to get the most "low level" access to the data. It is not for the faint of heart though, and can take around 1TB of storage and hours of CPU time to process full movies in this way, I know because I've done it.

I believe I've seen there is work being done to attempt this on CDs but it would have still been in the exploratory phases and not yet ready to start archiving with. It might seem like overkill to do this to something meant to be digitally addressed but I've experienced enough quirks with discs and drives when ripping that I would 100% be willing to switch over to a known complete capture system to not have to worry about it anymore. Post process decoding also allows for re-decoding data later if better methods are found.

[hunter2_]

The "unmolested data" would still have undergone error correction though, wouldn't it? I don't think a bin/cue rip would contain the redundant stuff, which GP seems interested in, nor the subcodes (of which some are represented in the cue file, while the bin file is PCM audio).

And at the risk of taking us well beyond the rainbow books, I'll just leave this here: https://www.psxdev.net/forum/viewtopic.php?f=70&t=1266

[taneliv]

You might do well enough with https://en.wikipedia.org/wiki/Cdparanoia without needing use different hardware to scan the disc. Instead it relies on the CD drive's ability to report on inaccuracies in keeping in sync with the grooves.

[sho]

this seems responsive: https://superuser.com/questions/140874/is-it-technically-pos...

[qingcharles]

I wonder if you could just tear the controller out of a CD/DVD drive and build a new one from scratch, kind of like the new floppy controllers being used now to read the raw magnetic data. You could just command the head to move to the center, find the beginning of the data and just keep reading until you hit the buffers.