Did you know the code for the Xbox 360 HD DVD player is 4.7 million lines? In comparison, Windows XP has 40 million lines of code, and the old Windows NT 3.1 has around 4-5 million lines of code. So yes, the software to play back HD DVD movies has the same amount of code as your operating system from 1993. Why? Because all the decoding, playback, and other functionality is software based.
Fun False Fact: Did you know half of that 4.7 million lines just goes to inserting frames of porn in Disney HD DVD movies?
In actuality, a lot of the functionality traditionally done in DSP (digital signal processing) chips or other hardware components in regular HD DVD players has to be emulated in the software for the Xbox 360. The intricacies after the jump:
In fact, HD DVD software playback is so taxing:
All 6 of Xbox 360's hardware threads are hard at work while playing back an HD DVD. At the moment, the player software pushes Xbox 360 harder than any other (save, perhaps, Gears of War during some particularly busy parts of the game).
Hardcore! The drive ships tomorrow.
Emergence Day [Xbox Team]