CD-i Application in Modern Tech - ReInventing the Wheel|
13/01/2008 | 17:46 GMT - Devin | Blog | Forums
Given our highly specialist niche of knowledge about a format considered long dead it's not often we look around technological issues in the here and now. However it's an interesting question with a multitude of answers but one in particular we want to focus upon today, that of video technology. Don't be afraid we're not going to bore you with the ins and outs of how the pioneering work of VideoCD gave rise to DVD. Although that's an interesting story onto itself, no, instead we're considering an innovative approach to breaking apart video called MPEG Branching. The first recorded instance of this that we have to hand was produced by Jean-Pierre Abello where he describes the technique in his Techical Notes #105 dated June 13, 1994. His strict definition of MPEG Branching or the more generic term Seamless Branching is as follows...
This development document explains the low-level seamless brancing mechanisms that allow a CD-i player with the Digital Video cartridge to play non-linear interactive Digital Video. Seamless branching provides the ability to play MPEG data from different streams or different portions of streams without breaking the delivery and presentation continuity of video or audio.
What relevance does this have today? We only started asking that question ourselves after playing the DVD release of 'Blade Runner: The Final Cut - Ultimate Collector's Edition'. Composed of 5 Discs some of which hold 3 different versions of the same film, not even mentioning all the extra content, we began to ask how this was done! The average DVD can only hold 2 hours of video footage, double that for Dual-Layer. Even at 4 hours the footage broke this barrier, with one of the Blade Runner Discs containing a 'US Theatrical Cut', 'International Theatrical Cut' and finally the 'Directors Cut'. In fact the answer was staring us in the face, it was, to quote the boxset itself, 'All Seamlessly Branched and Seperately Available on one Disc'. A relative obscure technique originally used on CD-i applied to a modern problem. Combining common elements of footage between each version this effectively eliminates the need to duplicate film on the DVD thus reducing the storage capacity required from the DVD. So that's how they got 3 versions of the same film onto one DVD! Maybe the technique was re-invented as an original concept, however we'd like to believe it was poached from the vaults of creative design within Philips Media!