Using readcd to read 3rd party discs

[Ashish Rangole <Ashish.Rangole@vexcel.com>]

I guess this is a novice level question.

I am planning to use readcd to read from a data CD/DVD. 
I understand that for discs written with "-dao" flag, readcd will
read exact number of sectors, whereas for those written w/o
"-dao" flag, readcd tries to read 2 sectors more than the actual
data sectors causing readcd to fail.

In order to avoid the error at the end of reading I think I should use
"sectors=" option with readcd. For a disc that I haven't written and
thus do not know how many sectors it has, how do I find that out? In
other words, how do I know what value should I give to "sectors=" when
I get a CD/DVD from a thirdparty which might or might not have been
written with "-dao" option?

Is there a better option than using readcd?

Thanks in advance for your help

Ashish