Sony is finalising a new high-capacity CD format expected to double the storage of a CD-ROM disc. But in addition to more storage space, the new format also brings new confusion to the optical disc storage sector, and new costs to consumers.

The consumer electronic manufacturer is in the final stages of formalising the format, which, at present, has the unwieldy name of Double Density CD-ROM/-R/-RW, (recordable/rewritable). It is expected to be finalised in September.

It will boost the available storage of a CD to 1.3GB - double the current capacity, but still only about a quarter of that available on DVD-ROM discs. But there is a catch: consumers will need to invest in new hardware to use the discs.

The new format is expected to offer lower prices than new DVD-based discs, according to Sony spokesperson Masami Kato, who was unable to estimate how much cheaper a Double Density CD might be than a DVD disc.

The format will add to an already dizzying number of choices in the recordable optical disc market. Consumers already face a choice between 640MB capacity CD-R and CD-R/W, 4.7GB DVD+RW (developed by Sony and Philips independently from the DVD Forum), 3.95GB DVD-R, 3.95GB DVD-R/W, 2.6GB first-generation DVD-RAM discs, and 4.7GB second-generation DVD-RAM discs.

Most of the benefits of the new system are likely to be realised by manufacturers of drive hardware and discs. Minimal change is needed to switch to the new format because the system is based on current CD technology, says Kato.

The new format features a smaller track pitch and pit length to accommodate greater data density, and makes changes in the error correction scheme, according to a Sony statement.

The system will also feature a copyright control system designed to prevent illegal copying of data on the discs.