,
Helsinki.
Availability At the time of the official launch, BBC HD was available universally on all HD broadcasters as a
free-to-air station. Satellite viewers could watch the channel on
Freesat or
Sky, who received their signal from the
Astra 1N satellite. The channel was also available to
cable television customers through
Virgin Media's basic package. The service was also carried on
digital terrestrial television in London, from
Crystal Palace, until May 2007 as part of the channel's trial and gradually made available nationwide on a region-by-region basis from 2 December 2009. The service expanded into the
Republic of Ireland with the channel's carriage on
UPC Ireland's Digital+ HD service from 5 August 2009 and on the
Sky Ireland platform from 27 April 2010.
Technical specifications The channel was broadcast at a
display resolution of 1440 by
1080i, which despite being less than the usual 1920 by 1080 resolution used for HD broadcasts was still acceptable to the
European Broadcasting Union (EBU) of which the BBC is a member. But after years of pressure from bloggers and tech experts alike, the BBC finally relented and switched BBC HD to full 1920 resolution for all broadcasts, not just when 3D was being broadcast. The channel encoded in
H.264/MPEG-4 AVC for satellite and terrestrial broadcasts and in
MPEG-2 for cable transmissions. Over time, changes were made to the way that the channel is broadcast or received. Following the launch of BBC One HD on 3 November 2010, both the new channel and BBC HD were
statistically multiplexed on the satellite feeds. Equally, on 6 June 2011, the
satellite transponder carrying BBC One HD and BBC HD was upgraded to DVB-S2. In addition to the satellite changes, alterations were made in March 2011 for the Freeview HD encoders to change automatically between
1080i at 50
fields per second to
1080p at 25 frames per second depending on the programme's
GOP. Unfortunately some receivers did not handle the transitions between these modes well, resulting in sound and picture disruption.
2009-2010 bitrate drop On 5 August 2009, the channel's satellite encoders on the
Astra 2D satellite were replaced by newer models. A side effect of this change was a drop in bitrate from 16
megabits per second (Mb/s) to 9.7 Mbit/s, leading to a large number of complaints to the BBC. The problem only occurred on the satellite platforms as the
cable versions were encoded by the provider themselves and so remained at 17 Mbit/s while the later launched terrestrial version was statistically multiplexed between 3 Mbit/s and 17 Mbit/s. Further anger ensued that the new satellite bitrate fell below the recommendations set out by the
European Broadcasting Union (EBU), of which the BBC is a member. These recommend a minimum of 12 Mbit/s, but as Andy Quested, principal technologist at the BBC stated, the current technology gave a consistent reliable output of 8-10 Mbit/s which would soon become the requirements with improved technology. Within four months of the change, by mid December, the number of complaints on this issue to the BBC reached 130 of which one was passed straight to the
BBC Trust. At around the same time a petition was added to the official
Number10 website in December 2009, petitioning then Prime Minister
Gordon Brown to bring the BBC into line with the EBU standards. The petition was sparked by the BBC's insistence that there was no problem with the bit rate. In addition, tests run by consumer publication
Which?, published in December 2009, found no significant decline in picture quality on the BBC HD channel, labelling the difference in picture quality between the new and old BBC HD broadcasts as "insignificant". Meanwhile, the international version of BBC HD continued to broadcast on satellite at the higher bitrate and screen resolution. The following year, on 30 April 2010, a delegation of viewers who had complained met with Andy Quested and Danielle Nagler to argue that BBC HD was failing to "deliver a very high quality technical service to viewers, by adhering to, or seeking to exceed, industry standards for picture resolution". The visitors took part in an evaluation of the new and old encoder's picture quality (by an ITU R500 test) and the results demonstrated that the new encoder, at much reduced bit rate, was not only "as good as" but actually much better than the old. The issue was resolved when, on 3 June 2010, the BBC introduced
variable bitrate encoding and fixed previous problems with mixing, fading and noise in pictures. The variable bitrate encoding allowed the channel to maintain the same average bandwidth while allowing an increase in bitrate for more demanding programme scenes such as fast movement. Equally the fixes for mixing and fading treated specific problems with changing scenes, while a configuration change for 'noisy' video means the BBC no longer needed to use noise reduction techniques that often reduced the overall picture quality. The changes were welcomed by campaigners.
3D broadcasts Whenever the BBC has broadcast programmes or events in 3D, there were other technical changes made to the channel that accompanied it. The BBC's first broadcast of the Wimbledon finals in 2011 Equally, the same occurred for the 2011
Strictly Come Dancing final
Presentation The BBC HD channel only ever ran at its peak for an average of twelve hours a day, usually from mid afternoon, and was only ever allowed to expand beyond these hours for coverage of significant sporting events. When off air, the channel would broadcast a looped series of clips identified as the
BBC HD Preview. These were of extended trailers and extracts for upcoming programmes on the channel separated by the channel's
idents. These segments were also notable in their hourly broadcasts of the HD
testcard, nicknamed
Test Card X, overlaid with a
BLITS audio test signal which allowed users to test and adjust their picture quality and position and the quality of their surround sound respectively. Equally, an audio visual synchronization animation was also broadcast hourly. These were used until 2009 when the presentation changed to a style featuring an ordinary scene which would become extraordinary when viewed through a rotating diamond shape. Original programme trailers and slides used the back-lit diamond shape as a base, while the 2009 versions used bright colours and textures inspired from the idents, for example the picnic blanket from the cat ident. ==Programming==