According to a patent filled by Warner at the U.S. Patent Office, the company is considering of creating a multilayer optical disc, which consists of several layers, including at least one layer conforming to a first format, and a second layer conforming to a second format. The formats can include CD, DVD, HD and BD formats.

Warner has already announced its support for both Blu-Ray and HD DVD technologies, and is expected to release later this month the first movie, "Lake House", on all three DVD, HD DVD and Blu-Ray disc standards simultaneously.

However, Warner engineers Wayne Smith, Alan Bell and Lewis Ostrover, have been working on a hybrid disc solution. According to the patent filled last August at the U.S. Patent Office, Warner is brainstorming a new three-layer, double-sided disc that will feature a BD-ROM layer and an HD DVD-ROM layer on the one side, and a red-laser DVD-ROM layer on the other side of it.

Theoretically speaking, such a medium could be manufactured since the Blu-Ray and the HD DVD laser lens have a different Numerical Aperture, which means that the Blu-Ray data layer and the HD DVD data layer are not placed at the same level under the disc surface. Te BD data layer is just 0.1-millimetres-deep on the top surface of a disc, while the HD DVD layer at a depth of 0.6 mm. The other side of the disc can normally have a DVD-ROM data layer.

However, the technical challenges in creating such a disc could be huge. The media manufacturers have faced significant problems in the past when manufacturing red laser dual-layer media, so the concept of a blue-laser double layer disc is even more challenging. The first layer should reflect just enough blue light for a Blu-ray player to read it okay. But it should also let enough light through for HD-DVD players to ignore the Blu-ray recording and find a second HD-DVD layer beneath. So the cost of making such a disc could be very high.

In addition, it is not sure that the current Blu-Ray and HD DVD players will be able to read such a disc, given that the disc may not strictly feature the optical parameters of the HD DVD and Blu-Ray specifications.

Warner's patent is accessible here.