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Internet TV: Media streaming

Posted on 9 Mar 2007 at 12:24

Taking out the PC

The alternative approach is to kick the PC out of the equation and go for a dedicated IPTV solution, such as BT Vision. This service works its magic via a 160GB twin-tuner Freeview PVR, offering both a Freeview digital terrestrial TV signal and a video-on-demand system based on Microsoft's IPTV. As with any true IPTV service, it's effectively an alternative to satellite or cable, but here the key selling point is a choice of films, music videos and catch-up TV-on-demand. Everything is available on a pay-per-view basis (29p for a music video, 99p for a programme or £2.99 for a film), although there are bundle packages costing up to £14 that gather particular types of content into Sky-style monthly subscriptions.

The catch and the trick behind the service are the same: it's only available to BT broadband customers. Vision's on-demand services require a constant 1.6Mb of bandwidth from the ISP's servers to the set-top box and, while that may seem peanuts in the days of 8Mb connections, the reality is somewhat different. Thanks to contention, most consumer broadband offerings will actually dip far below this during peak hours. Unfortunately, those are also peak viewing times. BT gets around this by invoking a Quality of Service (QoS) system, which prioritises Vision traffic through the BT Wholesale network. "We can guarantee that when somebody presses Play, it invokes the QoS session, the stream is initiated and they can watch their TV-quality pictures uninterrupted," claimed Richard Griffiths, director of technology strategy and development for BT Retail. Sadly, BT was unable to deliver us a test unit in time to verify this claim.

BT's service is currently standard-definition only, but the software and hardware is already equipped for high definition. The box includes an HDMI output and only two things stand in the way. First, the speed of the "last mile" connection between the BT exchange and the home; the current 8Mb ADSL Max service can't cope with the 8-10Mb/sec requirements of HD video. Second, the network itself. It's only when BT's 21st Century Network (21CN) technology is rolled out by 2011 that streaming HD video across the network becomes even a possibility. In the meantime, BT might allow HD movies to be downloaded and stored on the set-top box.

At launch, there were criticisms of the video-on-demand content, but deals with MTV, Paramount Comedy, Dreamworks, Sony BMG and Universal will add to a growing library. A deal with the Setanta and the FA to show 75% of Premiership football matches will also tempt more viewers.

Quality, however, may be a more persistent issue. The 1.6Mb pipeline means that on-demand content suffers from fairly high levels of compression, and early previews have complained of visible artefacts spoiling action sequences or sports. It's a far cry from Sky's HD channels.

Tailoring your network for video

Streaming video is the most demanding task your home network will come up against. Even though an 802.11g connection is theoretically capable of speeds of 54Mb/sec, they typically sit at around 25Mb/sec and can go much slower with traffic on the network or impediments such as thick walls. 480p video should be fine, but go up to 720p and the minimum 6Mb/sec constant bandwidth requirements take their toll, so it makes sense to optimise your network.

First, consider the position of the router. Place it somewhere central and high up, and watch for objects such as CD racks that might obstruct the signal. Have the router in the same room as the server or the player if possible, and think about a replacement antenna if signal strength is a problem.