There's no disk format to read from to determine what's available. Even burned disks with minimal data will say that if the session was closed. Blanks in my DVD player will thrash around for a long time unable to find data. A blank in my burner shows what you see...no free space even though there's nothing on it. Try to burn something to the disk and see what happens.
Hopefully this is the right forum!
To make a very long story short, I put a blank dvd disk into a mac not realizing that the file I needed was actually on my Windows 7 laptop. So I ejected the disk out of the mac and put it into my laptop. However, it now says that there is not free space on the cd. Why? The other four disks read perfectly and I actually put it into my computer first before putting it into the mac and it was fine. What's the deal and can I reverse it?