Monthly Archives: January 2013

On configuring Apple TV

Partly on impulse and partly because I’d been discussing media streaming with my electrician, I bought an Apple TV (3rd generation). For a start, it seems a real steal at £83 and can stream from iTunes, YouTube and Netflix. The fact it doesn’t yet support LoveFilm Instant or Sky Now is a bit of a downer, but this isn’t a review of the Apple TV. Rather, it’s a collection of useful tidbits for getting the thing working better, in particular with AirPlay.

What’s AirPlay?

The Apple TV is a streaming media player. I’ve already mentioned a few sources for that streaming (iTunes, Netflix), but what if you could stream directly from an iPad or iPhone? This is what AirPlay does. When you have an iOS device or even a Mac laptop with Mountain Lion, you can mirror the display to your big-screen TV via the Apple TV box as long as they are on the same network.

This is pretty cool stuff, but there was one big flaw: when I first tried it, the performance was shocking. Completely unusable. Second time I tried it (on a different network), same thing. Being the highly rational person I am, I immediately blamed Apple and their AirPlay implementation. How could they seriously foist this garbage on us?

I didn’t give up though and I had this nagging feeling that the network could be the problem, even though WiFi is supposed to give us up to 54Mb/s. On a whim, I bought a TP-Link Powerline kit (which I see has gone up in price since I bought it) to provide a more reliable network connection between the router and my Apple TV. In one stroke, a significant improvement in the AirPlay performance. It still wasn’t really usable though, but it did highlight WiFi as the likely culprit.

Tuning the WiFi

After tweeting this, someone responded and pointed out that WiFi contention might be an issue. So I started investigating. In the UK, WiFi breaks down into 13 overlapping channels. Your WiFi access point is configured for one of these channels. So are probably a bunch of others in your vicinity. At this point, all I knew was that 15+ WiFi access points were broadcasting in range of my equipment and that many of these were probably interfering with my own network.

The first suggestion I came across was to set the access point to 802.11g only. I’d be surprised if many people have equipment that doesn’t support ‘g’. I certainly don’t, so I duly made the change.

The second suggestion was to pick an uncontested or at least weakly contested channel. To be honest, I didn’t even know what channel my WiFi was configured for. Fortunately, I found a magic incantation for my Mac laptop to discover what channels all the WiFi networks were using:

/System/Library/PrivateFrameworks/Apple80211.framework/Versions/Current/Resources/airport -s

That’s one ugly command line, but that’s only because the airport utility isn’t on the path by default. Anyway, running that gave me a list of all the WiFi networks and their channels. If you happen to be on Windows or Linux, it shouldn’t be too hard to find an appropriate tool to give you this information.

What I found out was that channels 1, 6, and 11 were the most prominent, with a few networks on 7 and 9. At first glance, it looks like I have plenty of choice for the channel since there are 13 available to me. But it’s not at simple as that. These channels overlap:

(This image linked from http://www.airportal.de)

Any channel that overlaps with another interferes with it. As you can see, a predominance of channels 1, 6 and 11 pretty much mess up all channels! What could I do? I basically deduced that channel 13 was the best bet since the only channel in use it overlapped with was 11, and 13 has a larger stagger over 11 than 12, thus reducing the risk or strength of contention.

I don’t really know whether the above is accurate, but once I picked channel 13 for my WiFi access point and limited it to 802.11g only, AirPlay suddenly started working. And working well. This is great, because I can access things like LoveFilm Instant and Sky Now via my laptop or iPad and stream to my TV, even though Apple TV doesn’t directly support either of them. I also noticed that the Netflix streaming became much more reliable after switching to Powerline.

So if you’ve been having buffering and lagging issues with Apple TV (or any media streamer for that matter), then I hope the information I’ve presented helps you sort them out!