AirPlay is the name for Apple’s latest method of streaming audio and video from one device to another, such as from an iPad to a new Apple TV. To use AirPlay for video, make sure you’ve updated to iTunes 10.1 (on your Mac), iOS 4.2 (on your iPhone, iPod touch, or iPad), and Apple TV 4.1 (for the second generation Apple TV). This article explains why you might want to use AirPlay for video — as well as why you might not be able to use it the way you want.

Why should I care about AirPlay? I can already stream video (and audio) from iTunes on my Mac to any Apple TV — by sharing my iTunes Library.

You’re right. By enabling Home Sharing, you can set up your Apple TV to access your iTunes Library on your Mac. In fact, with the new Apple TV, such sharing is the only way to access your Mac’s iTunes Library content. The option to sync and store content on the Apple TV itself, available for the first generation Apple TV, is gone. Once set up, you’ll find your iTunes Library listed in the Apple TV’s Computers menu. From here, you can navigate to the video you want to play.

Accessing iTunes content via AirPlay works differently. Instead of selecting content from the Apple TV, you work from iTunes on your Mac. The first step is to select your Apple TV from the AirPlay popup menu in the lower right corner of the iTunes window. You then select the video you want to play. Assuming you’ve previously turned on AirPlay from the Apple TV, the video should stream to the Apple TV.

One caveat: Any type of video streaming to any Apple TV only works with video formats supported by the Apple TV. 

Via Home Sharing or AirPlay, you are able to play iTunes video on your Apple TV. So why would you need both? In particular, why would you want to bother with AirPlay? Three reasons:

• AirPlay can be simpler and more flexible. Library sharing is great if you want access to your Mac’s playlists and complete iTunes Library collection. It’s also your only option for streaming video from a Mac to a first generation Apple TV.

AirPlay can work better if all you want is access to a single selection, such as a movie. With AirPlay, it doesn’t matter whether or not a Home Sharing connection has been made. And you don’t need to navigate the Apple TV’s menus to locate your choice. This can be especially convenient for playing video from Macs other than your own. For example, if a friend comes over to visit, he can use AirPlay to easily stream a movie from his MacBook’s iTunes Library to your Apple TV.

• For audio, AirPlay works with devices beyond the Apple TV. You can directly connect to supported audio devices, such as ones from JBL, iHome and others. With such devices, there’s no longer a need for an AirPort Express (AirTunes) intermediary.

• AirPlay allows you to connect to a new Apple TV from iOS devices. As I’ve already indicated, you can use AirPlay to connect your iPhone, iPod touch, or iPad to a new Apple TV. Beyond a doubt, this is the most exciting aspect of AirPlay. It means you can start playing a movie on your iPad, for example, and wirelessly switch to watch the movie on your large-screen television.

In my testing, iPad-to-Apple TV streaming worked very well. I could select a movie from the iPad’s Video app and have it playing on my television within seconds. Once streaming a movie, I could pause or otherwise control the playback from the Apple TV remote, the iPad’s controls, or even from my iPhone’s Remote app.

[Note: Unfortunately, there is no way to select Apple TV over AirPlay from an iOS device before starting the movie. Yes, there is an AirPlay item accessible from the iPad’s multitask bar. To go to it, double-click the Home button to bring up the multitask bar. Next, swipe your finger across the bar to the right (on an iPhone or iPod touch, you’ll need to swipe twice). However, this item only gives access to audio over AirPlay.]

Can AirPlay stream any video from any app on my iOS device to my Apple TV?

Nope. Only apps updated to support AirPlay video can do this streaming. Currently, AirPlay video is available from Apple’s iPod, Video, YouTube and Photos apps. From the Photos app, you can only stream still photos, not movies — not even movies you take yourself via the iPhone’s camera.

It gets worse. The needed APIs for AirPlay video are considered private. This means that Apple will not allow any third-party apps to stream any video over AirPlay. That’s right. You won’t be seeing an AirPlay option in apps such as Netflix or ABC Player. At least not until Apple changes its policy on this matter (which I hope will happen in the not-too-distant future).

There is one exception to all of this. If you’re willing and able to jailbreak your iPad or other iOS device, an app called AirVideoEnabler supposedly allows third-party apps to stream to the new Apple TV (I have not yet tested this).

Audio AirPlay options are more flexible. For starters, from iOS devices, third-party apps can stream audio over AirPlay/AirTunes. Further, AirPlay in iTunes on your Mac can stream audio to the both the first and second generation Apple TV models.

What about game apps? Will it be possible to have a game’s display stream to an Apple TV over AirPlay — possibly leaving the iPad or iPhone free to serve as the game’s controller?

Playing iOS games over AirPlay would be great. Absolutely. It’s obviously not possible now, given what I just said about private APIs. But what about down the road? As I understand things, it still won’t be possible even if Apple relaxes its API restrictions.

As explained in this Macworld article, AirPlay works by “packaging” intact video and streaming it to the Apple TV, where it is buffered and played back. This method would not work for the live-action time-sensitive demands of a game. 

Can you stream video via AirPlay from Mac applications other than iTunes? 

Currently, no. As covered on a Rogue Amoeba webpage, the makers of Airfoil discuss the possibility that Airfoil may eventually work with AirPlay to provide this functionality.

Can you steam video via AirPlay to a Mac or iOS device?

No. Macs and iOS devices do not show up in AirPlay menus. You can stream content from them — but not to them.

What about playing copy-protected (HDCP) content over AirPlay?

If your television has HDCP-support, you should be able to play both non-protected and HDCP-protected content over AirPlay to an Apple TV. However, as I covered in my Macworld Bugs & Fixes column last week, things don’t always work the way they are intended.

Bottom Line

For streaming video, AirPlay is an exciting first-step in the right direction. The key phrase in the prior sentence is “first step.” AirPlay still has a ways to go before it “realizes its true potential.”