AirPlay: How Does it Work And What Devices Can Use it?

What is AirPlay & How Do YOu Use it to Stream Digital Music?

AirPlay Icon
AirPlay can be used to wirelessly stream music. Image Courtesy of Apple.

If you've seen the AirPlay function on your iPhone, iPad, or iPod Touch then you might think that it's connected in some way to AirDrop -- another wireless option built into iOS.

However, AirPlay isn't for file sharing like AirDrop.

It is in fact a wireless technology that was developed by Apple for streaming content rather than transferring files. It was originally called AirTunes due to the fact that only digital audio was supported.

But, it was renamed as AirPlay when more features were added. It can now be used for streaming video as well as audio.

It's made up of a proprietary set (or stack) of protocols that enables you to use your iOS device (iPhone, iPod Touch, iPad) to stream media using a Wi-Fi network.

How Can Music be Streamed?

For digital music, you can stream to your TV (in conjunction with an Apple TV box), share with other devices (via Airport Express), or listen with AirPlay compatible speakers. It's also possible to stream digital music to several rooms (with AirPlay speakers of course) using iTunes on the PC and Mac.

Examples of Hardware Devices That use AirPlay

Just like any wireless network, you need a device that transmits information (AirPlay Sender) and one that receives it (AirPlay Receiver).

  • Examples of AirPlay Sender Hardware: Apple portable devices running the iOS operating system (iPhone, iPod Touch, and iPad). These have to be running at least iOS version 4.2 or higher to use AirPlay. A Mac or PC with iTunes can also be set up as an AirPlay sender device.
  • Examples of AirPlay Receiver Hardware: Apple TV, Airport Express, and AirPlay-compatible speakers are the main ways of receiving wireless media from AirPlay senders. However, other examples include: stereo systems, audio-visual receivers, and docks.

Can AirPlay Transmit my Song's Tag Information?

Yes, it can.

For example, if you use Apple TV to stream music, videos, and photos from your iOS device to your HDTV then metadata such as song title, artist, and genre can be displayed.

Album art can also be transmitted and displayed using AirPlay -- the JPEG image format is used to send cover art.

How does AirPlay Work and What Audio Format is Used?

To stream digital music over Wi-Fi, AirPlay uses the RTSP protocol (Real Time Streaming Protocol) -- this is actually the original AirTunes part. The Apple Lossless audio codec is used (over the UDP transport layer protocol) to stream two audio channels at 44100 Hz.

The audio data is also scrambled by the AirPlay server device which uses a private key based encryption system.