DVD-5 (consumer) vs Retail "Professional"

[Cabadam]

I've been trying to figure this out for a while, but just can't seem to figure out any good reason for this.
Obviously we have the technology to create the 9GB DVDs (they are on store shelves everywhere), but as consumers, we are only able to purchase discs that are HALF that size. Why is that? If they can do it, why are the same things not available to us here?

Anyone?

Thanks!

[StrawMan]

There really is no difference between the "size" of a DVD-5 and a DVD-9, but the DVD-9 has two layers of the same space. Think of it as 2 DVD-5s sandwiched together. Currently available drives can only RECORD to one layer of a DVD-R or DVD+R, the multi-layer recorders should be available sometime this year.

All drives (that I know of) are capable of reading both layers of a DVD-9, although on some the "layer break" (where it stops reading from one layer and starts reading the next) is very obvious.

I know this is confusing because CD-Rs are the same size physically as a DVD, yet the DVD has a much larger capacity, so one might assume that a DVD-9 is just "larger in the same way." This is not the case.

[Cabadam]

Hmm... I understand what you are saying about it. But I don't understand why it has taken so long for US to get it. I mean, obviously these kind of burners are there (hence why we have the commercial DVD-9)... so why can't we do the same?

[Kedirekin]

Retail DVDs aren't burned so much a built. The pressing process involves a lot of big and very expensive equipment - a pressing machine to press pits into a plastic blank, a gas sublimation machine to give the pressed blank a reflective surface (or partially reflective surface in the case of the intermidiary layer), a bonding machine to join the layers together to make a final dual-layer disk.

That's part of the reason why consumer DVD-9 hasn't been available - the machinery is too complex, to big, and much too expensive.

[ukb007]

Just adding a line to what Kedirekin has written, the home-burnt DVDs do not really have pits, they only have spots made non-reflective to the impinging laser beam.

Regards.