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The World of HD

The World of HD. Dr. Hayden So Department of Electrical and Electronic Engineering 24 Oct, 2008. Area You Ready?. What does HD really mean?. H igh D efinition Full HD 1080p 1920 x 1080 pixels + progressive scan PAL: 768x576 Supposedly higher quality video, TV.

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The World of HD

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  1. The World of HD

    Dr. Hayden So Department of Electrical and Electronic Engineering 24 Oct, 2008
  2. Area You Ready?
  3. What does HD really mean? High Definition Full HD 1080p 1920 x 1080 pixels + progressive scan PAL: 768x576 Supposedly higher quality video, TV More Pixels = Higher Quality?
  4. Three Characteristics of Display Panel Size The physical dimension of the panel A 42” panel has a diagonal measurement of 42” Display Resolution The number of picture-elements (pixels) along each X-Y direction In a HD panel: 1920 x 1080 pixels Dot Pitch The distance between two pixel of the screen Panel Size = Display Resolution * Dot Pitch
  5. More Pixel = Good? Human eye can identify 120 pixels per degree of visual arc i.e. if 2 dots are closer than 1/120 degree, then our eyes cannot tell the difference At a distance of 2m (normal distance to a TV) our eyes cannot differentiate 2 dots 0.4mm apart. Closer to TV => easier to differentiate pixels Far away => cannot tell the difference screen Minimum: 2 arc minute
  6. Image courtesy of www.carltonbale.com
  7. Why is HD difficult? One major problem is bandwidth The amount of video data needed to be processed for each frame HD:1920 x 1080 x 50 Hz x 24 bits = 2.48 Gb/s PAL (progressive, digital)768 x 576 x 25 Hz x 24 bits = 133 Mb/s 10x more data needed to be processed, stored
  8. HDTV Transmission Digital Broadcast Vs conventional Analog transmission Over-the-air transmission of HD content Began in Dec 31, 2007
  9. DTT in Hong Kong DTMB – Digital Terrestrial Multimedia Broadcast (formerly DMB-T/H) Same as mainland China Different from rest of the world Two standards MPEG-2 for Standard Definition TV - Basic H.264 for HDTV – Higher-tier Higher-tier supports full H.264 + interactive
  10. Storing and Playing HD Movies DVD was not capable The standard Physically infeasible A double-layer DVD-9 can store around 8 GB of data ~= 4 hours of PAL video compressed using MPEG2 720 x576 @ 25 fps, < 10 Mbps variable video bitrate About 2 hours on a DVD-5 Using the same encoding for HD video 1080p24 requires ~5 times the storage Need new storage + new encoding
  11. Blu-ray Discs Next generation DVD Same form factor New Storage Single side: 25 GB Double side: 50 GB New encoding Uses MPEG2 or H.264/AVC Using MPEG2: 2 hours on single side Using H.264/AVC: ~4 hours single side, 8 hours DL
  12. Enabling Technology Blue-violet laser Blu-ray uses violet 405nm laser DVD: 650nm near infrared CD: 780nm Shorter wavelength allows more information to be stored per unit area Why not use it in DVD? It was very expensive to produce blue laser Until him…
  13. Story of Shuji Nakamura A research scientist at Nichia Chemical Industries Ltd. in Tokushima, Japan Graduated with a PhD but decided to stay in Tokushima, instead of Tokyo, to raise his child A research team that shrinks from 3 people in 1979 down to 1 in 1991 Invented the world’s first commercially viable blue-violet solid state laser diode Beat all major research universities Beat all big companies: RCA and Hewlett-Packard to Matsushita and Sony
  14. Summary Given the right condition, HD does give better quality video Over the air broadcast is achieved through digital broadcasting Need new equipments For stored video, Blu-ray is the next standard Blu-ray was only made possible by discovery of ShujiNakamura
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