After reading about the iPhone for a while, memorising facts from its spec-sheet is just an occupational hazard.  So, Apple's cellphone has a maximum screen resolution of 640 x 480 for compatible content... doesn't it?  Ars Technica say no, and they've been playing with video that encoded at 720 x 576, 25fps on both the iPhone and the iPod Touch, a figure that's funnily enough exactly the same as a PAL DVD.  Videos encoded at that resolution can be viewed both through mobile Safari and funneled over from iTunes, although of course it only shows up at the 480 x 320 resolution of either device's screen.

So why is this important, if you can't see the difference?  As Ars Technica explain, it's all about optimising your video library for playback on multiple devices:

"[It] can be [useful] if you want the same files to be playable the mobile device and on the computer screen or TV. If you are interested in experimenting yourself, don't forget to stick to baseline H.264 encoding and remember that these files will not play on older generation iPods"Iljitsch van Beijnum, Ars Technica

The upside is that movies bought from the iTunes store are actually being delivered in higher resolution than you might expect, given Apple's quoted compatibility for the iPhone; Iljitsch found his copy of Punch-Drunk Love came in at 853 x 366, which would look far better through, say, an Apple TV than a 640 x 480 version might.

[via Gizmodo]