My observations have been that the "brand" of DVD you purchase plays a major roll in how things behave.
As I don't have to pay for the DVDs ( most of the time ) I have tried from the very cheap to all brand names available here.
So, my observation is that it doesn't make a difference.
In all fairness, I have to say, that when you buy brand names here
, you still don't have a guarantee , as they are all << made in China >> , as we jokingly say every time we are 'done in'.
as in my post above, I still compared the bits of a ? bad ? one ( K3b ) to a < good > one ( acetoneiso ), and the total bit count stayed the same.
So, I am not sure what's the real story