Digital Home Standards

Originally published in the May 2008 issue of Personal Computer World

Standards for the digital home

We’re all being encouraged to make the most of digital media, but make the wrong choice, and you face compatibility nightmares. Nigel Whitfield explains.

Sometimes, it seems, you can’t move for gadgets designed to let you share content on your home network, with streamers, NAS applicances and even mobile phones boasting that they’ll let us access our music and movies anywhere. The reality is somewhat different. There’s a wealth of different standards involved, and even when you have two devices that sport the same logos, there’s no real guarantee that they’ll do what you want.

Take a network with a couple of UPnP media players – the Pinnacle Soundbridge, and the Helios X5000; there’s a Mac with iTunes, a NAS server with UPnP, and a Nokia N95 phone, which also boasts support.

Both the Soundbridge and the X5000 can play back music from the NAS server. They can browse music on the N95 too, if it’s set up to share it on the home network. But they can’t browse the iTunes library on the Mac, unless the Firefly server software is added. And the Nokia phone can browse the network to see files on the NAS device, or the Firefly music server – but it can’t actually play anything from them. It can, however, send a stream to be played on the Soundbridge, even allowing you to use the phone’s volume control to change the level on the Soundbridge. But it can’t do the same trick with the X5000. And all that’s before we’ve added a few more standards into the mix.

Alphabet soup

Standards are supposed to make life easier; and in some areas they do – buy a bit of wireless kit with the WiFi logo on it, that sports and 802.11g sticker, and it’ll connect to any WiFi network with the same standard. The theory behind UPnP media devices is the same – but just as wireless users can find that it’s the details, like encryption support, that stop two supposedly compatible devices from working perfectly together, so the world of home networking is full of potential pitfalls.

So, what standards are you likely to come across in your quest for a networked digital home, and what do they all mean? In this article, we’ll concentrate on the area of home entertainment and media, and related systems that work with them – we won’t go into home automation, for example.

When it comes to devices that serve up or play back content, UPnP and DLNA are things you’re going to hear a lot about. Rather than being specifically about media, UPnP – Universal Plug and Play – is a way for devices to configure themselves automatically on your network; it even allows, for example, for a gadget to request that your router open specific firewall ports.

But it’s also important in terms of home media because one part of it – UPnP AV – defines types of devices, such as media servers, media controllers and media ‘renderers’- playback devices – and how they discover each other on the network. As we saw in our example, right at the start though, that’s not necessarily enough to make sure everything works together. Although UPnP AV goes far enough to ensure that, in our example, we could see send music from our N95 to a Soundbridge music player, there are still gaps.

And it’s those gaps that DLNA starts to fill in. Short for Digital Living Network Alliance (; if you’re shopping for home media equipment at the moment, and want to be sure of the best compatibility, it’s probably the DLNA certified logo that you should be looking for.

A DLNA certified product has to include UPnP support, which takes care of devices being able to find each other on the network, but in addition, it specifies certain file formats that need to be supported too, and that if a device is trying to send information to another one that doesn’t understand the format, it will transcode it. And there are requirements – and testing – for interoperability, all of which will help to avoid the sort of issues we talked about earlier.

There are four main types of DLNA device, just as with UPnP AV; Digital Media Servers and Digital Media Players do pretty much what you’d expect. There are also Digital Media Renderers – things like photo frames, wireless speakers or TVs – and Digital Media Controllers, which can control what appears on a renderer; also in the mix are mobile versions, which tend to have slightly different requirements for the formats they should support. And, of course, some devices are more than just one type. A media player TV or set top box may also be capable of being used as a renderer, allowing you to select a photo on your mobile phone, for example, and send it directly to the TV, rather than having to browse the phone from the TV’s remote control.

If you’re thinking of buying, the DLNA web site has a database of certified products to help you make sure you buy devices that will work together.

Other standards

The DLNA isn’t the only game in town, of course. There are some new standards emerging, and some already here. Microsoft’s Windows Media Connect, for example, is also based on UPnP and so will work with a wide range of existing players, but offers better functionality when paired with another WMC device, like the XBox 360. It may be tempting to look at if you have a new Windows Home Server and a console, but beyond the XBox there aren’t many devices that support it fully.

If you use iTunes and its sharing functionality, you’ll find that music is shared using a protocol called DAAP, and the way in which devices discover each other relies, instead of UPnP, on an Apple technology called Bonjour; Airport Express remote speakers use a different protocol too.

Fortunately, that doesn’t necessarily mean you can’t pick and mix; many NAS units, for example, can run both a UPnP server, including DLNA compliant ones, and at the same tie share music via software like Firefly (, which implements the DAAP protocol needed for iTunes. And similarly, devices like the Soundbridge will see information that’s available via both DAAP and UPnP media servers, while a playback device that’s DLNA certified should see WMC servers too, since they’re both built in UPnP AV.

A key standard to watch out for is MPEG4, which can mean very different things in different contexts; simply having it written on the side of a box won’t necessarily guarantee your files will play back. Read more here.

Linking up

It’s also important not to overlook the connectivity side of things; while the DLNA specs embrace WiFi and Bluetooth, those are both standards with different versions, and it’s important to make sure that you choose compatible equipment, especially with regard to things like encryption.

When it comes to higher quality media, though, many people now are ditching the crowded WiFi airwaves and using home power line networking; with a rated throughput of 200Mbps, even the real world performance of HomePlug AV is good enough for high definition, and as far as your devices are concerned, they’re connected to a standard Ethernet. But if you thought WiFi interoperability was tricky, you need to be just as careful with mains networking.

The HomePlug AV standard can co-exist with the earlier 14 and 85Mbps HomePlug standards, in that they’ll all run on the same wiring – but it won’t talk to them. It’s not, in that regard, like Ethernet, where a 10Mbps and a 100Mbps device can be plugged into the same switch and communicate. And while different vendors’ HomePlug AV kit will talk to each other, watch out for similarly specced but incompatible equipment, using the DS2 mains networking standard, or Panasonic’s own proprietary system, which will appear inside more of their kit in future.

On the positive side, it’s a little easier to add HomePlug AV to your network, thanks to new routers like Zyxel’s P660HPW, which has it built in, so you’ll just need an adaptor for your media player.

What to buy

So, if you’re looking for digital home entertainment equipment, what should you be looking for? We reckon that you’re best off sticking to the key standards – WiFi for your wireless, HomePlugAV for main networking, and DLNA certified equipment for media player, servers and other gadgets. It’s also worth keeping an eye out for Certified Wireless USB, when products finally appear in the UK.

Meanwhile, Microsoft’s Windows Media Connect isn’t going to go away any time soon – but nor is it going to take the market by storm, in our view. The same is likely true for Panasonic’s mains networking; unless you find it inside your new TV or DVD recorder, stick with the standards.

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