One of the things I really like about the PlayStation 3 is the combination of the Blu-ray and the hard drive. Without the Blu-ray the game wouldn't have fit on a disc, for example the audio for the different languages won't fit on a DVD. We're only using the hard drive as a cache, the game doesn't need to be installed, but the fact the hard drive is on every PlayStation 3 helped our streaming technology dramatically.
We are constantly streaming animations, level data, textures, music and sounds. It would have been impossible to get this amount of data at that speed to memory without the hard drive. And of course on top of that we use the SPU's to decompress all this data on the fly.
As I said earlier, we couldn't have done Uncharted without the Blu-ray, at least at the quality we wanted to make it. To get such high-resolution textures and movies, a Blu-ray was indispensable to achieve the graphic quality of Uncharted. We fill the disc at 91 percent and it's optimized, meaning we don't duplicate any data. That includes all our game data, sounds, 7 spoken languages and 102 minutes of movie.