I have been collecting some info about reading 'bad' (damaged in any way, not copy protected) CD/DVD's for some time. Few questions related (and not) to this:
1) Suppose I sent to my drive a MODE SELECT command with Error Recovery Parameters (Page 1) set to read sectors regardless of errors (RC/TB as 1).
Are there any situations when READCD command will return me check_condition and no data anyway (I am thinking specifically about errors in sector header/synchronization bytes)?
2) Is there any way to determine whether a CD/DVD supports mode select parameters mentioned above other than testing it empirically? Does any specs/drive reviews on the web include such info? (I am asking beacuse none of the drives i have access to support those. I would be thankful for suggesting at least one DVD-RW which is buyable at the moment and can do this for sure). Is a sheep-test related to this in any way?
3) I am also interested in the interleaving mechanism in both CD and DVD. From what i read, on a CD each sector is being spread over 108 other sectors. Sector is made of 98 24-byte 'blocks' + 98 byte subchannel data (why is it 108 sectors then? Did I miss something?). Suppose we are looking at sector 100 - is it physically stored through sectors 100-208, 46-154 or differently? What is the sequence of the 24-byte blocks - 1,2,3,... or is it shuffled somehow?
On how many sectors is the data spread on a DVD (when 16 'frames' are coded together)?
Thanks for any responses.