For the purposes of this test, we downloaded six films in total, to check the stability and consistency of the system. But for the performance tests we focussed in particular on Wanted and The Dark Knight, given our familiarity with these films in their Blu-ray incarnations.
Starting with the picture quality delivered by the Xbox movie service, it's best summed up as good without hitting the same heights provided by the best Blu-ray pressings.
The HD versions of The Dark Knight and Wanted we downloaded both clearly look HD, for instance, with a significant increase in detail and sharpness. It's a relief, too, to discover that even with The Dark Knight, a relatively long film, there doesn't seem to be too much nasty video compression going on. In other words, HD pictures seldom become softened during action sequences, and don't suffer with hefty amounts of MPEG blocking over backdrops.
The Xbox does a sterling job of reproducing the extra colour vibrancy and subtlety experienced with HD pictures too, and pictures are decently contrasty - even if dark parts of the picture arguably look just a fraction too dark from time to time. However, while our two main HD movie downloads look sufficiently sharp and detailed, there's no doubt at all that the Blu-rays of both films look sharper still - significantly so when it comes to Wanted.
For instance, you get a much clearer sense of the cinematic grain in the Wanted transfer when watching the Blu-ray than you do when watching the Xbox download. Also edges look more defined, textures look more precise, crisp and tangible, and the picture generally looks slightly more three-dimensional. To try and give you a sense of the level of difference we're talking about here, if we say that the Blu-ray of Wanted scores a 10 for picture quality while its standard definition DVD version scores a five, the Xbox would notch up an eight.
It's difficult to say whether the slight reduction in crispness and detailing is down to the fact that the Xbox delivers a 720p transfer rather than the 1080p transfer from the Blu-ray, or is caused by some file compression processing. But the reasons behind it aren't really all that important; all that matters is that the difference exists, and videophiles should be aware of it.