If this subreddit is not the best discussion for this please point me to the right place even if its outside of reddit.
I have many CDs (~20) that are in good physical condition but some are unreadable while others are readable with problems. They have been cleaned with cloth and been tried in 2 different CD/DVD roms. There are minimal scratches with no affect on actual readability.
Problem: Some disks read fine but aren’t able to copy properly. They have a few “bad sectors” but the content is 90%+ fine. In File Explorer while browsing the disk, I am able to see pictures clearly with no artifacts. Copying from the disk directly or using a program to force copy will result in extremely slow copy speeds when it hits a “bad sector” taking several minutes to copy a 3-5MB file. Opening the file after the copy completes will show many artifacts on the image or most of the time the image is too corrupt it doesn’t even preview, while it shows fine in preview on the CD (not opening the file, just shows the picture on icons). Suggestions? Anybody knows why the image preview is fine on the icons but doesn’t show properly after?
Problem 2: Half of my CDs don’t read at all. They have been left close to a window with sunlight for a while. Could that be the cause of the unreadability? Some CD/DVD roms use different colored lasers, could that change the outcome? While hard to tell, it’s still possible to see the burned portion with data on the disk. Suggestions?
**Conclusion** 15 hours of time or so wasted on this crap. I used ISOBuster but didn’t bother with complicated recovery techniques. I just made the program copy everything possible and skip when it comes to damaged sector. Got about 60% of all data completely recovered, 2 disks are still completely unreadable, and was able to get about 70-80% data from 3 other disks, and one disk is only 25% fine. Tried ddrescue but it did the same thing but it’s much more complicated to use and takes much longer.