On Aug 20, 2012 7:47 PM, "Andrea Conti" <[email protected]> wrote: >
[snip] > > > > Yes, +RW, -RW, but don't know much more on this other than older DVD writers > > would only do one format not another and if you didn't pay attention to the > > specification/limitations of your hardware you could end up buying the wrong > > type of DVDs. Someone more experienced on recording media could answer this > > better. > > Every modern recorder does both standards; depending on both the burner > and the reader you might find that one standard works better than the > other (i.e. has lower read error rates). Trial and error seems to be the > only working approach... > > As for the standards, if you're just burning backups they're basically > equivalent. The +RW standard is theoretically more flexible as media can > be formatted in a "packet" mode which allows (almost) random r/w access, > but in my experience software support and reliability have always been > lousy, so forget about it. > > +RW media cannot be erased in the same way CD-RWs are erased, -- you can > only overwrite it with new data. -RW behaves the same as CD-RWs in this > regard. > > If you need rewritable DVD media with reliable random r/w access (but > this doesn't seem to be your case), there is a third standard (DVD-RAM) > which uses special disks with hardware sector marks. Drive support is > not hard to find nowadays (the drive you cited actually supports it), > but writing is slow, good media is expensive and the disks cannot be > read in most "normal" dvd drives; I have no idea about the state of > software support in Linux. > +RW *can* be erased, or else it won't be called RW :-) That said, the difference is much deeper than differing metadata. Among which : * +RW uses Phase Modulation, -RW uses amplitude modulation. This gives +RW much more robustness than -RW * +RW blanks provide more info on the energy level required to burn, IIRC up to 4 energy levels each tuned to a certain burning speed (e.g., 1x, 2x, 4x, and 8x). This *greatly* improves the success probability of burning. -RW only provides energy level info for the maximum burning speed; if your drive doesn't support that speed, it'll have to guess, and the results are usually ungood More history : The CD Standard was originally developed by Philips, then adapted to the data world requirements, including CD-R(W). The DVD-R standard was originally developed by Panasonic, but Philips had a spat with Panasonic because in Phillips' view, the CD-R standard has shortcomings they (Philips) want to fix; Panasonic was more interested in getting DVD-R out of the door asap. This resulted in Philips -- together with someone else, was it Sony? -- to independently released the DVD+R standard. CMIIW Rgds,
