Tuesday, 24 July 2012

Super Hi-Vision

         British Broadcasting Corporation will test broadcast London 2012 Olympics footages in the latest Super Hi-vision (SHV) television format. This format has 16 times the resolution of the existing High Definition TV format and with 22.2 multichannel surround sound. This provides a amazing picture quality and viewers feel a strong sense of reality. One can watch Olympics in Super Hi-vision theaters in  BBC Broadcasting House in London , BBC Pacific Quay in Glasgow and  National Media Museum, in Bradford.  SHV was developed by NHK (Nippon Hōsō Kyōkai) in English it is Japan Broadcasting corporation.


This ultra high definition televsion format has 4000 scanning lines and it contains 7680x4320 pixels per frame. SHV camera uses 8 megapixel CCD camera. It uses four channels Green1, Green2, Red, Blue, instead of traditional Red, Green, Blue channels. Thus around 32 mega pixel data is generated for every frame. It uses MPEG-2 video compression format with 4:2:2 sampling format. AVC/H.264 codec are reconfigured to transport SHV signals to mobile devices. SHV has a angular resolution 40 to 50 degrees, which gives the sense of realness. It has 60 frames per second instead of the conventional 25 frames in PAL and 30 frames in American NTSC colour system.

It needs 24 speakers to create a 3D spatial impression to the viewers. This helps to augment the sense of reality. It has 9 speakers in upper layer frequency, 10 speakers for middle layer frequency, three speakers in lower layer frequency and at last two speakers for  low frequency effect . It uses 48 KHz sampling rate, 24 bit Pulse Code Modulation which results in 28 Mbps or Dolby-E systems having 7 Mbps.

Researchers at NHK used to phychological methods to figure out the relationship between sense of reality verses the viewing angle. They found  higher the viewing angle more the feel the reality. Viewing angle below 40 fail to provide any reality feel. From 40 to 80 sense of reality increases with the viewing angle. Increase in viewing angle beyond 80, do not dramatically increase the 'feel'.

In 1953 televisions had a screen size was 12 inch.  Fourteen inch colour  TV's  emerged after 1960. Size grew to 20 inch in 1975 and it reached 29 inch in 1990. Beyond this size conventional Cathode Ray Tube (CRT) cannot be manufactured. So 50 inch LCD or LED Flat screens were developed in 2006. Viewing distance and resolution has a direct relationship. Optimal viewing distance of conventional TVs are four to six times the diagonal of the TV. For a TV having a diagonal size of 21 inch, needs a viewing distance of seven feet.  Thus size of the room limits the size of TV screen.  So it becomes necessary to increase resolution to have bigger screens at home.

An uncompressed SHV signals require around 50 Gbps and with digital compression bit rate requirement will be between 200 Mbps to 400 Mbps.The present 12 GHz systems can handle upto 52 Mbps. So they move to 21GHz range of frequency (21.4 GHz-22.0 GHz). But at this frequency rain act as a spoilsport. Non-real time broadcasting is used to combat rain attenuation effects.

 Khushu National Mueseum's  SHV theater was inaugurated in October 2005.  This  is the first time  SHV  system was deployed for public use.

SOURCE:
  • Steps Towards the Practical use of Super Hi-vision by M. Maeda et al from NHK Science and technical Research laboratories.
  • "Super Hi-Vision -  research on future ultra HDTV system", article by Masayuki Sugawara, NHK, EBU Technical Reveiw - 2008 Q2
  • S.Sakaida, N. Nakajima, A. Ichigaya, and M. Kurozumi, "The Super Hi-Vision Codec," Proceedings of ICIP 2007, pp. 21-24.
  • Transmission Techniques for Broadcast Satellites in the 21-GHz Band aiming for "Super Hi-Vision" Broadcasting, Broadcast Technology No.24, Autumn 2005 pp 8--13
  • http://www.bbc.co.uk/blogs/bbcinternet/2012/07/super_hi_vision_ultra_hd.html