Friday, December 14, 2007

Ultra High Definition Video

Super Hi-Vision, also known as Ultra High Definition Video, UHDV, Ultra High Definition Television, UHDTV and UHD is an experimental digital video format, currently proposed by NHK of Japan.

Super Hi-Vision's main specifications:

  • Resolution: 7,680 × 4,320 pixels (16:9) (approximately 33 megapixels)
  • Frame rate: 60 frame/s.
  • Audio: 22.2 channels
    • 9 — above ear level
    • 10 — ear level
    • 3 — below ear level
    • 2 — low frequency effects
  • Bandwidth: 21 GHz frequency band
    • 600 MHz, 500~6600 Mbit/s bandwidth
UHDV resolution shown in comparison to other digital video formats.
UHDV resolution shown in comparison to other digital video formats.

The new format with a resolution of 7,680 × 4,320 pixels is four times as wide and four times as high (for a total of 16 times the pixel resolution) as existing HDTV, which has a maximum resolution of 1920 × 1080 pixels.

Experimental technology

Because this format is highly experimental, NHK researchers had to build their own prototype from scratch. In the system demonstrated in September 2003 they used an array of 16 HDTV recorders to capture the 18-minute-long test footage.

The camera itself was built with four 2.5 inch (64 mm) CCDs with a combined resolution of only 3840 × 2048. They then resorted to pixel shifting to bring it to 7680 × 4320.[1]


An UHDTV camera
An UHDTV camera

The system was demonstrated at Expo 2005, Aichi, Japan, the NAB 2006 and NAB 2007 conferences, Las Vegas, and at IBC 2006, Amsterdam, Netherlands. A review of the NAB 2006 demo was published in a Broadcast Engineering e-newsletter.[2] In November 2005 NHK demonstrated a live relay of Super Hi-Vision (UHDV) program over a distance of 260 km by a fiber optic network. Using dense wavelength division multiplex (DWDM), 24 gigabit speed was achieved with a total of 16 different wavelength signals.

Capacity and storage media issues

The eighteen-minute uncompressed UHDV footage in the NHK demonstration consisted of 3.492 terabytes of data, with each minute requiring 194 gigabytes. In this format, an uncompressed two-hour full length UHDV movie would require 23.28 terabytes of data storage. However, using current MPEG-2 compression technologies, a UHDF video signal with a format of four times the width and four times the height of the current 1080p HDTV standard would require 16 times the bitrate, or 6 GB per minute, with a two-hour feature film requiring 720 GB. Further compression using H.264 (MPEG-4 AVC) or VC-1 video compression technologies could reduce the bitrate by half relative to MPEG-2 compression, or 3 GB per minute or 360 GB for a two-hour film.

Note that these compressed data rates assume they scale linearly with absolute resolution, which is a conservative estimate. In practice, the actual compression ratios would be much higher for UHDV signals, effectively reducing the bitrate and data storage requirements. Nevertheless, based on the conservative compression estimates, a 12 cm Holographic Versatile Disc at 3.9 terrabytes capacity would be able to store 650 minutes (roughly 11 hours) of MPEG-2 at 6 GB per second, or 22 hours of H264 or VC1 compressed UHDV, compared to the 18.5 minute HVD capacity of uncompressed UHDV. By comparison, a current octal (eight-layer) Blu-ray disc (with a capacity of 200 GB) would be able to store approximately 36 minutes of MPEG-2 compressed UHDV, or 72 minutes of H264 or VC-1 compressed UHDV, compared to only one minute of uncompressed UHDV.

A 50 TB Protein-coated disc (PCD) would be able to hold over four hours of uncompressed UHDV data, or up to 284 hours of H.264/AVC/VC-1 compressed UHDV. If stabilizing ferroelectric materials is accomplished for practical, permanent data storage with 12.8 petabytes of capacity, it could be possible to store 1024 hours of uncompressed UHDV, or 24,064 hours of H.264/AVC/VC-1 compressed UHDV.

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