Recovering CD coaster(I/O error) data

[acid45]

Hey everyone, I burned about 40 DVDs of avis of my DVD collection, totaling to 40 DVDs with 6 movies on each. I would rather not re-rip half of my DVDs since it took such a looong time.

Instead, I would rather write on the disk that special care needs to be taken to recover the data, if posible. I did some reasearch on the net and it seems like there are a lot of propriatary software that doesn't come free, which is a real bummer.

I tried using the DD command but this ends up in the same result as using the cp command. I was reading that this is most likely due to the way the DVDs were burned, and that I may be able to use sector sizes or block sizes to recover the data using DD, but it wasn't very in depth. It mentioned using tools like isoinfo, but again, didn't get into the detail that my noobie *** requires.

Can I use the dd command to somehow recover the data I lost?
Any idea on what else I can do, other than re-rip the DVDs, or download them. I'd rather not redo a lot of work I had already done, but it is a learning experience. Next time, use the command line.

Any help would be appreciated...

[Pafnoutios]

If you were never able to read from it after burning it, then it probably did not burn properly and you'll have to do it again (I recommend at a slower speed next time).
If it was readable for a while then maybe you'll have to redo it. Is there any physical damage to the disk? Scratches or anything?

[acid45]

Well, I can read from the disk just fine, some files actually copy over and I can read the size of all files. Unfortunately, I didn't try the disc before formatting so I can't just burn it again. Also, it seems like no matter how I define the speed, it always tries to burn at the burners fastest speed. I always set it to 1 but it says it's burning at 4 and then only actually reads at between 1.8x and 2x. There are no scratches that I can see. Well there are some fine ones that I can see if I look at it in the light the right way, but barely noticeable, Like the fine scratches on a car that only buffing and polishing gets rid of.

I guess I SOL.

[stumbles]

I've not used it but have you tried dd_rescue?

"Like dd, dd_rescue copies data from one file or block device to another.
You can specify file positions (called seek and Skip in dd). However,
dd_rescue does not abort on errors. It can also copy starting from the end
of a file."