Following Apple’s iPad event yesterday, the company quietly released iTunes 10.6, a small update that adds compatibility for the new iPad and Apple TV hardware, improves the reliability of Apple’s iTunes Match service and, most significantly, adds support for purchasing, downloading and viewing 1080p content from the iTunes Store.

The update also includes a number of other smaller changes and enhancements. As usual, we’ve gone through the update in detail to see exactly what has changed.
1080p HD Video
Probably the most significant change in iTunes 10.6 is the addition of support for 1080p video, released in conjunction with matching higher-resolution content on the iTunes Store, as well as the new third-generation iPad and third-generation Apple TV. It’s also worth keeping in mind that these are the only two standalone hardware devices—other than Macs and Windows PCs—that will currently provide support for the higher-quality video content.

It’s also important to note that the iTunes Store has not seen a wholesale updating of HD content into 1080p. Much like the SD-HD divide, many shows continue to be available only in the older 720p resolutions, while others have been updated to add the higher-resolution 1080p format. At this point it doesn’t appear that any content is exclusively 1080p—sensible considering the number of Apple devices out there that are still limited to 720p as their “HD” resolution.
Purchasing and Downloading 1080p Content
Unlike the distinction between standard definition and HD content, 1080p content is not sold on the iTunes Store as a separate edition. Instead, HD content that is available in 1080p is indicated on its iTunes Store page with a note that both 720p and 1080p versions are available. Somewhat confusingly, HD content that remains in 720p only currently appears as it did before, with no reference to its resolution. In other words, the absence of any mention of 720p or 1080p in an iTunes Store item means that only a 720p version is available.

The single HD catalog item on the iTunes Store includes both the 720p and 1080p versions, and unlike the standard definition versions included with HD purchases, only a single HD version is downloaded. A note on the iTunes Store item page below the HD resolutions indicates which version you will actually be downloading when purchasing an item. This is set to 720p by default, presumably to retain maximum compatibility with Apple’s existing hardware, but you can change this option by taking a quick trip into your iTunes Preferences and choosing 1080p from the When downloading High Definition videos option on the Store page.

Unfortunately, there is no way to change this option on the fly; you’ll need to visit the iTunes Store preferences if you decide that you prefer a given movie or TV show in an alternate HD resolution.
As before, purchasing an HD version of a movie or TV show will also download the standard definition version alongside it. This applies to both 720p and 1080p HD purchases—you will get one HD version in your preferred format, and one SD version of each file.
Upgrading Past Purchases
The default download preference also applies to HD movies and TV shows that you re-download from your purchase history via iTunes in the Cloud. Since the 1080p versions of HD videos are not sold as separate items, this means that users can basically get free 1080p upgrades to any of their existing movie and TV show purchases that are now available in the higher resolution. In other words, as long as you bought the HD version of an item to begin with, and it’s now available in 1080p, you can simply set your default download resolution to 1080p in your iTunes Preferences and then go to your purchase history and download the higher-resolution HD versions.

Unfortunately, the Purchase History page doesn’t provide any information on whether an item is available in 1080p or not—you’ll need to take a look at the actual item page on the iTunes Store to confirm this before taking the time to re-download an item.
Accessing and Playing 1080p Content
HD content will continue to be displayed in your iTunes video listings with a small “HD” badge to the right of the title, in much the same way as it has since the introduction of HD content to the iTunes Store. Unfortunately, this badge does not provide any indication of whether the HD content in your library is 720p, 1080p, or both; even if you have both the 720p and 1080p versions in your library, only a single HD badge is displayed.
Despite the lack of any indicator, however, the good news is that you can have both HD resolutions stored in the same iTunes library in the same way that HD and SD versions co-exist. iTunes will automatically choose the appropriate version when syncing to an iPod or iOS device or playing back on the Apple TV. For playback using iTunes on your computer, you can choose a default playback resolution in much the same way as before; on the Playback screen in your iTunes Preferences. The former checkbox to play videos in standard definition has been replaced by a drop-down menu that allows you to choose from one of the three formats now available.

In iTunes, you can also check which versions are available, and choose a default version for a specific item by right-clicking on an item and choosing the Versions sub-menu.

The Summary page for a given item will also display the HD resolution information for a given video track. Note, however, that this pulls up the information for the currently selected version (from the version menu), not necessarily the highest quality version available.

Under the hood, iTunes stores 1080p files with a “(1080p HD)” suffix in the filename, while 720p files continue to be named with simply an “(HD)” suffix, as before.

From a file size point of view, expect 1080p HD downloads to be approximately 50% larger than their 720p counterparts, or about three times the size of the equivalent SD version. While this may seem like a smaller size increase relative to the resolution bump (1280 x 720 up to 1920 x 1080, or just over double the resolution), Apple appears to be using a more restricted bit-rate of around 5.5 Mbps for 1080p content, versus the 4 Mbps it has traditionally used for 720p content. It remains to be seen whether this will have any practical impact on 1080p quality for the average user or will be something that may be of concern to only the most serious home theater enthusiasts, but the bitrate is on the low side for 1080p content.
Regardless, considering the ability to re-download content later from iTunes in the Cloud, most users will probably prefer to stick with the 720p versions for now to save space and download bandwidth unless they plan to purchase a new iPad or Apple TV next week.
Syncing HD Content
Not much has changed with regard to syncing HD content to an iPhone, iPad or iPod touch. Obviously, only the earlier iPads and Retina Display-capable iPhone and iPod touch models provide any support for HD content at all, and these continue to be limited to 720p. You will not be able to transfer 1080p content onto these devices at all, however if you have an SD or 720p version in your library as well, the best available non-1080p version will be transferred to your device—this means that if you have a 1080p and SD video without a 720p version, your iOS device is going to get the SD version. This is something especially important to keep in mind since 1080p HD purchases will include an SD version, but no 720p version unless you specifically go and download it separately from your purchase history.
We expect that iTunes will have an option available for the new third-generation iPad to allow users to select SD or 720p content for the new device in much the same way that the Prefer standard definition videos option works for the current iOS devices.
iTunes Match
The release notes for iTunes 10.6 also note “many improvements for iTunes Match,” including improved song matching, improved album artwork handling, downloading and display, and issues where songs may skip when playing from iCloud. All of these changes appear to have taken place under the hood with no visible UI elements beyond some minor cosmetic changes to the iTunes Match setup screens.
From our testing thus far, iTunes Match appears to be faster and more reliable within iTunes 10.6, although we have not seen any significant improvements on the iOS side, particularly regarding missing artwork, even with the new iOS 5.1 update.
Movies in the Cloud
Although this is not an iTunes 10.6 change—the feature is accessible to iTunes 10.5.3 users as well—it’s worth noting that users in the U.S. can now re-download some previously purchased Movies by going to the Purchases section on the iTunes Store.

This works in pretty much the same way as it does for other types of content; a new Movies tab appears in the Purchases section, and users can choose to download HD versions where available, or only the SD versions. The list can also be filtered to only show movies that are not already in the iTunes library. This feature is only available in the U.S. for now; it is unclear when and if it will be expanded to other countries.
Other Changes
A couple of other smaller changes have been made in iTunes 10.6 that are worth noting here, as well.
Convert Higher Bit Rate Songs During Sync
The Convert higher bit rate songs to 128kbps AAC option in device sync settings now allows users to select a bit-rate of 128kbps, 192kbps or 256kbps for converting songs on-the-fly during a sync. This feature will be of particular interest to users who like to keep lossless libraries within iTunes and have previously found 128kbps AAC to be unacceptable for down-converting to an iOS device.

Watch (almost) Instantly
iTunes 10.6 borrows a page from the Apple TV, allowing users to now begin watching a video while it’s still being downloaded from the iTunes Store. A Ready to Watch dialog box will appear once enough of a video has been downloaded to begin properly watching it while it is still downloading.

iTunes Store Login Dialogs
It’s a small change, but authentication dialogs for the iTunes Store now display the username and password fields vertically rather than horizontally.

Conclusions
The addition of 1080p content to the iTunes Store will be a welcome addition for many users, although Apple appears to have made some tradeoffs in file size versus HD bitrate, and it therefore remains to be seen whether the quality of the 1080p content that the iTunes Store is providing is going to be up to par with comparable content from other media sources such as Blu-ray Discs. Specs aside, the real question will be whether the actual user experience of viewing the content will matter in any measurable way.
Although not entirely tangible, the improvements to iTunes Match are also a welcome addition for a service that appears to have had a rocky start.
Beyond these changes, however, iTunes 10.6 doesn’t really offer anything compelling for many users. If you’re planning to buy a new iPad or Apple TV, you’re going to pretty much require this update, and if you’re not, the new 1080p content will not be of much interest unless you regularly view video content on your computer and have a large enough screen to justify the additional download and storage requirements. In other words, there’s no particular reason for most users not to download it, but no incredible changes that make it mandatory, either, except for owners of new devices.