Many of the companies behind the Blu-ray optical video disc format unveiled prototype players, while Toshiba gave the first public demonstration of its competing format at the Ceatec 2002 exhibition in Chiba, Japan.

The two formats, which are both still in the design stage, are based on blue lasers, which allow the discs to hold several times more data than DVD discs — up to 27GB per layer in the case of Blu-ray and 20GB per layer for Toshiba's AOD (advanced optical disc).

Both formats are already battling for the title of successor to DVD Video in the consumer electronics space, and technology from their development is expected to play an important part in future optical disc formats targeted at computer use.

Blu-ray was announced in February this year by a group of companies headed by Sony and grew out of work the company was doing with Pioneer on DVR Blue, a blue laser-based system project unveiled at the Ceatec expo in 2000.

Among the companies showing prototypes of Blu-ray recorders at Ceatec was JVC — a surprise because the company was absent from the nine-member group that established the format. Other prototypes were on display from consortium members including Sony, Panasonic, Sharp and Pioneer.

The recorders looked impressive but they are still far from completion and many were displayed in a way that hid large component boards typical of such prototype devices.

Alongside the players, the companies were also showing media for the format. There are three capacities of Blu-ray media — 23.3GB, 25GB and 27GB — each of which are single-layer discs. Double-layer discs, with twice the capacity, are also possible.

While stressing that commercial plans for the format have yet to be decided, representatives of both Sony and Matsushita at Ceatec said their companies hope the media will cost around ¥5,000 (£26) per disc when they go on sale.

Toshiba, which is one of the few major consumer electronics companies not behind the Blu-ray format, unveiled in public for the first time a prototype of its new AOD (advanced optical disc, pictured).

The AOD is being developed by Toshiba and NEC and has the ability to store around 20GB of data on a single-layer recordable disc and 15GB of data on a single-layer prerecorded disc, said Naoki Morishita, a specialist at Toshiba's optical disc development department.

Its announcement, made in August this year, set the stage for a format battle between AOD and Blu-ray.

Toshiba proposed AOD to the DVD Forum, which it chairs, as a next-generation successor to DVD Video, but the Blu-ray group has not approached the DVD Forum.

The Blu-ray group maintains its format is a new generation system and should not fall under the DVD Forum's auspices.

Based on the prototypes on display at Ceatec 2002, it is still too early to tell which format has the edge although the sheer number of Blu-ray prototype players make that format difficult to ignore.