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24th August 2008, 20:28

I made some notes of what i was able to find out about BD+ browsing the web. Maybe this helps to clear things up and avoid misunderstandings:

Quote:

BD+ involves the player running a small virtual machine whenever a BD+ disc is inserted. The virtual machine is a small BD+ content code interpreter that includes 100 lines of code and 60 different instructions. The VM loads additional code from the Blu-ray disc, which can perform one of three functions:

- Transform code, which is used to correct sections of video data which are deliberately corrupted on the video stream part of the disc. If hackers strip out only the video code itself, it will display corrupted sections without the application of transform code. This code may also be used to add digital watermarks to certain discs, which can then be used for forensic investigations of leaked copyrighted material.
- Basic countermeasures, which can check a player that is known to have had its hardware hacked for example, a patch to the drive's firmware and detect and respond to this hack. This allows new discs to disable playback on standalone players that have been hacked, without having to revoke the license keys of the entire model or line of players.
- Advanced countermeasures, which can load native code that runs directly on the Blu-ray player during the playback process. This code can do any number of things, but is designed to provide additional methods of protection should the basic countermeasures fail.

Once the disc is removed from the player, the virtual machine unloads and is no longer present in memory. This returns the Blu-ray player to its initial state, so that even if a machine fails to play a BD+ title, it should still (again, in theory) play previously-released Blu-ray titles that do not have BD+ protection.

According to the Blu-ray Disc Association (BDA), for hackers to successfully attack the BD+ system they would have to first extract the AACS keys (which has already been done quite successfully) and then overcome title-specific security code by reverse-engineering the BD+ virtual machine. While this last bit is definitely an additional challenge, it is by no means impossible.

The announcement of the BD+ spec means that some studios that have been holding off on releasing high-definition content may now be more willing to release titles: it was rumored that Fox Studios had been delaying titles because of the previous AACS cracks. The availability of more titles on Blu-ray than HD DVD (since the latter does not support BD+) could swing the format wars even farther in Blu-ray's direction, especially when combined with events such as the Blockbuster announcement.

More worrying than a resolution of the high-definition format wars, however, is what studios might want to do with the additional powers that BD+ provides them. The ability to run any sort of code in the name of "advanced countermeasures" also brings the power to limit content by other means: timed-release and expiring discs are just some of the possibilities.

If you have any further (useful) information please feel free to post them here.