Recordable DVD--Great Idea, but Which Format?

A war's brewing, and the prize is the spot presently occupied by your VCR.

Soon, you may be willing to dump your faithful tape recorder and sub in a shiny new box that plays and records equally shiny digital discs. A number of early products and prototypes that fill that role were shown at the recent Consumer Electronics Show.

DVD seems to be the format of choice, but it presents a problem because there are three distinct types of rewritable DVD: DVD-RAM, DVD+RW, and DVD-RW.

All three rewritable DVD options have stated data capacities of 4.7GB per each disc side, but none of the current recorders offers a straight digital connection to your satellite or cable service. All inputs are analog, save for fast IEEE 1394 (FireWire) options on some. You may get to input that digital signal once all copy protection concerns have been addressed, but that capability is not in this generation of recorders. The recorders already provide some copy protection and won't let you make a bit-for-bit copy of the DVD movies you rent or buy.

You Get Some Controls

All three DVD formats let you select the data transfer rate, or bit rate, of the recording. Higher rates yield better quality recordings but also eat up more of your disc space, so you get less video on the disc. Both DVD+RW and DVD-RW can adjust that bit rate on the fly: You can preset a desired level but the recorders will also examine the source material--say, that action movie you're taping off TV--and will raise the bit rate to ensure that you don't get splotchy video during explosions. They will scale back the bit rate in other, less-demanding scenes so that you get the level of recording you wanted, on average. DVD-RAM can do the same if you set it to the variable bit rate mode. Other modes on DVD-RAM yield a constant bit rate.

As if that isn't enough, TDK, Plextor, Sanyo, and others have formed an alliance and are proposing an extension to the familiar CD-Recordable and CD-Rewritable formats, called MultiLevel Recording technology. MultiLevel triples both the speed of the drives and the disc capacity. Its developers say it may eventually offer a fourth VCR alternative for consumers in the near term while DVD recorder prices come down.

MultiLevel CD-RWs will be able to store up to 2GB of data per disc, and will also incorporate some copy protection. No consumer recorders have yet been announced. But it's likely that, if these machines do let you feed in a digital signal, you won't be able to copy it at the highest quality available on the recorder, suggests Bruce Youmans, executive director for marketing at TDK.