We’ve already seen prototypes of 100GB and 200GB evolutions of Blu-ray. Now Pioneer has pushed Blu-ray technology to 400GB! Both PC World and TechRadar UK reported on the development. Best of all, it is reportedly backward compatible with today’s Blu-ray hardware. In theory that means existing drives could handle the higher capacity media with a firmware update.

Pioneer has achieved this capacity by stacking sixteen 25GB layers, compared to the two 25GB layers on a standard Blu-ray disc. They’ve done this by solving the interference issue which results from stacking an increasing number of data layers on top of each other. But they’ve managed to do so using the same optical specifications of the objective lens, maintaining Blu-ray compatibility.

Expanded capacity like this would likely first be used in data applications, for backup, etc. While some unusually long films might be able to use more than 50GB for HD home video, 50GB is enough for most videos up to 1080p. But there are already newer video standards appearing, such as 3D video or 4k video, which is 4096×1716. That’s the resolution used for digital cinema projection in movie theaters, and it is nearly 3.5x the resolution of ‘Full HD’ 1080p home video. When you go to higher resolutions and/or add data to support 3D displays, then you need higher capacity media.

Backwards compatibility could be useful as such discs could use the ‘top’ two layers just like a standard Blu-ray disc that would work in any existing player. While the remaining layers could be used for newer standards like 4k or 3D, and work in newer players that support those technologies.