Ars Technica recently noticed that file sizes on 1080p videos were smaller then you would normally expect. The updated 1080p files hold more 2.25 times as many pixels as 720p files, so you would expect the files to be 2.25 times larger. But of course due to some Apple magic (and compression) they were able to keep the files sizes relatively small in relatio to the video upgrade.
The picture below shows detail on the bottle which is more visible in the 1080p version on the right side. They noticed that there isn’t much need to upgrade your current video files as the improvements are minor in older videos, but going forward there is no reason the 1080p files shouldn’t be your first choice.
It is worthwhile to note that the new 1080p files will not work on your older iPads or Apple TV, only the third generation iPad, iPhone 4S and newer Apple TV.
The reason that the 1080p versions of the iTunes Store videos can be a good deal better without doubling the file size—or worse—can be found in the tech specs of the new AppleTV and the new iPad. The AppleTV now supports H.264 compression for 1920×1080 resolution video at 30 frames per second using High or Main Profile up to level 4.0, the iPad and the iPhone 4S the same up to level 4.1. The profile indicates what kind of decompression algorithms the H.264 decoder has on board—the “High” profile obviously has some tricks up its sleeve that the “Main” or “Baseline” profiles known to previous devices don’t support. The level value indicates how many blocks or bits per second a device can handle.
So what do you guys think? Is the newer 1080p file size worth the extra download wait?