UPnP: the saviour of connectivity

The UPnP Forum's White Paper, "Understanding Universal Plug and Play", suggests various dreamy scenarios for UPnP technology in the home. UPnP can be used for more than simple device connectivity.

For example, UPnP-based alarm clocks could trigger other UPnP-based devices when you wake up (i.e. turning on lights, switching on the TV). Or UPnP-based kitchen appliances could be connected to a home network, enabling Information for each one (i.e. model, make, and serial number) to be retrieved for service calls.

You can download and read the UPnP's White Paper for yourself, here. While the scenarios it uses might seem a little far-fetched, it serves to illustrate that UPnP is a platform designed to span the digital home, connecting PCs to DVD players, lights to security cameras.

Improving the standard

UPnP's immediate future is a little more modest, however. UPnP is being used as the basis for a new UPnP AV standard that's being pushed by the Digital Living Network Alliance (see Digital Home? Look for the logo). "The digital home," says the DLNA, is an evolution of the idea that PCs, consumer electronics and mobile devices should work together seamlessly through a wired or wireless network to share digital media within a home environment."

UPnP AV is based on the original Internet-friendly UPnP protocols, but it's designed to connect and control a whole range of audio-video (AV) devices, such as: TVs, DVD recorders/players, amplifiers, digital media adapters and PCs.

The current UPnP specification typically relies on application software (the 'control point') to manage communication between the content host (the 'media server') and the content playback device (the 'media renderer').

So if you buy a Philips Streamium SL400i, for example, you'll have to install and run the Philips Media Manager software on your PC before the adapter can access and stream any of your video, audio or digital photos.

In contrast, the UPnP AV specification is capable of the sort of 'zero-configuration' networking we mentioned earlier. It still retains the 'media server' and 'media renderer' concepts that are vital to UPnP connectivity, but the 'control point' can be integrated into either of these elements or exist separately from it.

The intelligence of the control point is key. As Andrew Liu, former Business Development Manager for Intel's Network Architecture Lab, now Senior Product Manager at Pure Networks, points out: "In UPnP AV, the control point discovers audio/visual devices on the network, locates the content selected by the user, determines a common transfer protocol and media format, and initiates and controls the transfer to the renderer, including instructions on how the content is to be rendered (brightness, contrast, colour levels, volume, and so on) and how the content should flow (play, stop, pause, seek, next, previous)."

This means that a PC acting as a media server won't enable, say, a Philips SLA 5500 wireless audio player (the media renderer) to see photos or video files, because these files will be unplayable on the Philips hardware.

All audio files will, however, be accessible, even those that aren't directly supported by the media renderer. Some UPnP AV control points, such as Nero's MediaHome Server, are capable of transcoding media on the fly.

Such a control point would be able to convert a WMA file into an MP3 file if a media renderer didn't natively support the WMA format.

Building for the future

Like most digital home technologies, UPnP is very much an early adopter technology. But the fact that Philips is using it as the basis for its Streamium range is proof that UPnP does exactly what it says on the tin.

The improved UPnP AV standard, meanwhile, will give frustrated digital home enthusiasts what they've long hoped for - a new, easy-to-use home networking and content sharing system that puts a CE sparkle on sober IT technology.

Want to try it for yourself? As mentioned earlier in this article, there are several UPnP-capable software and hardware solutions available. In terms of software, Microsoft has released a second version of Windows Media Connect, although its official compatibility list is disappointingly small. Other servers such as TwonkyVision, Allegro and TVersity are all worth a look.

As for today's hardware, the TwonkyVision web site lists the following adapters as being UPnP-compliant.

Buffalo LinkTheater
D-Link DSM-320RD
Netgear MP101
Philips Streamium SL300i
Philips Streamium SL400i
Philips Streamium MX6000
Philips SLA5500
Philips SL50i
Pinnacle ShowCenter 200
Roku SoundBridge
Terratec Noxon Audio

A word of caution: while we've successfully streamed MP3 audio to an MP101 and piped DivX video to a ShowCenter 200, the UPnP standard can often be fiddly and flaky, while UPnP AV is very much in its infancy.

With the DLNA poised to slap logos on a list of new digital home-friendly products, it might be wise to wait until 2006 before investing in such streaming equipment. The technology is only going to get better.

Connectivity isn't the problem here; compatibility is. And to ensure maximum compatibility we need to be able to buy the sort of intelligent, zero-configuration devices that we've talked about in this article.

The UPnP AV standard has the potential to take the digital home by storm, making it accessible to a mainstream audience who want to take advantage of PC power, not be hindered by PC complexity.

This could be the revolution that we've been waiting for.