How does Airplay work?

[emvath]

Could someone help me understand exactly how Airplay will work? As you will soon see, I'm not a techno-genius.

So let's say I'm sitting on my couch in front of my home stereo and I want to "airplay" something from my PC. I can use my iPhone and pick what I want to listen to and my PC will then send the music to my stereo.

*Is my computer sending the signal through my wireless router to my stereo receiver (or perhaps they are wire networked) or is it sending the signal through some other source kind of like bluetooth does?

*If the signal is passed through a wireless router, does the stereo receiver that receives it then become a networked peripheral on my PC?

*Is my computer sending the digital signal directly to my receiver which then uses it's own digital to analog converter to pass it on to the speakers? Or does the computer decode it the files and send the receiver a signal of what it should sound like?

 

[KDR]

What you are describing is how Airtunes works, and while I haven't confirmed this I believe that Airtunes is now called Airplay which includes additional features like video streaming from computers and IOS devices. I will describe what Airtunes currently does from the perspective of an advanced user, not a true techie.

Using Airtunes, the computer streams data to an Airport Express or Apple TV through a wireless router. From the Airport Express or old Apple TV, you can send either an analog cable or an optical cable to a receiver or powered speaker. The new Apple TV just has an optical output. You can use the iPhone like a remote to control what the computer streams. I assume the Airport Express includes a Digital/Analog converter and that it can be used or bypassed depending on the type of cable that is used. I am running it both ways using an optical cable to connect to my receiver and stereo mini cables to connect to Bose Sounddocks. The computer just sees a wireless device that is Airtunes-enabled, so it's not like a network device that you can browse in Finder.

I understand that Airplay-enabled devices are coming out (speakers, receivers, etc). I haven't confirmed this, but I assume that these devices have built-in wifi which is the main difference. Before you had to buy an Apple TV or Airport Express to feed a signal to a receiver or powered speaker.

Edit: I just confirmed through my current setup that Airtunes is now called Airplay. The main difference that I notice is that I can control the volume of each individual speaker from iTunes which wasn't possible before.

 

[betman]

I too would like to ask about how airplay works.

When I play something from my laptop on my tv (using Apple TV), what route does the stream take?

I take it not just Apple TV but also the router is always the intermediary? So if I can then I might as well hook up my computer using a LAN cable since nothing is going direct from my computer to Apple TV when using wifi?

 

[priitv8]

You could even directly interconnect AppleTV and computer with an Ethernet cable, leaving all intermediaries out completely.
You can read up the technicalities here: Unofficial AirPlay Protocol Specification