Ofcom Principal Broadcasting Adviser Greg Bensberg revealed at the HD Masters conference in London that up to six HD channels could be created on the Freeview digital terrestrial platform. However the plan involves no new spectrum, but instead relies entirely on technology improvements to increase efficiency within the existing six Freeview multiplexes, writes Richard Dean.
Bensberg said that capacity could be doubled by adopting MPEG-4 compression across all channels, instead of the current MPEG-2. Further savings would be realised by switching to the later DVB-T2 transmission standard, and a 64 QAM (Quadrature Amplitude Modulation) scheme rather than 16 QAM.
In total 40 Mbps of bandwidth would be released, enough to support five 8 Mbps HD channels with a 720p line structure (720 lines scanned progressively). “Five channels is not enough,” retorted Glodina Connan of Harris Corporation in the subsequent panel session, to vigorous applause.
Scepticism over Ofcom’s motives has been running high ever since Digital TV Group Director General Richard Lindsay-Davies claimed in The Guardian newspaper that, just a day after Ofcom’s Digital Dividend Review in March recommended that all spectrum liberated by analogue switch-off (ASO) be sold in 2008, the UK Treasury estimates included a _36bn windfall from spectrum sales – twice the forecast made last December.
Bensberg was adamant that money-making was not in Ofcom’s remit, adding the baffling claim that the regulator could even be prosecuted for doing so. Citizen, consumer and spectrum efficiency implications remained the only issues under consideration, he said.
Conceding that the changes would be disruptive, and that the shift to 64 QAM could not occur before until ASO is completed in 2012, Bensberg suggested that an additional HD channel could be added by scrapping three existing SD channels.
This also met with a stony response, as delegates struggled to identify suitable ‘victim’ channels on the popular Freeview platform. A consensus emerged that more of the post-ASO Digital Dividend cake should be made available for HD, which was seen as the next logical step in the evolution of terrestrial television.
Bensberg also dismissed a suggestion that the once-in-a-lifetime opportunity of ASO be seized with a ‘big bang’ conversion of Freeview to an all-HD platform, claiming that viewers needed to have the choice of standard definition TV.
