1 / 57

DTV&DVB

Chapter IV. DTV&DVB. By Theerayod Wiangtong, PhD., DIC Mahanakorn University of Technology. Part I: Shifting from Analog to Digital Television System. History of Television. First Monochrome Broadcast of Electronic Television in England, 1936

derica
Télécharger la présentation

DTV&DVB

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chapter IV DTV&DVB By Theerayod Wiangtong, PhD., DIC Mahanakorn University of Technology

  2. Part I: Shifting from Analog to Digital Television System

  3. History of Television • First Monochrome Broadcast of Electronic Television in England, 1936 • Introduction of Color Television based on the three primary colors, ~1968 • Digital Television is the next big revolution in television, ~2000-2006 • multimedia standards converge under the digiTV standards • services can be experienced whenever, and wherever the consumer wants • enhanced quality, multiplication of channels, interactivitiy, access to Internet services • interacting with content is the major issue

  4. Color TV systems • Analog Color TV systems: Video Production, Transmission, and Reception.

  5. Why not using RGB directly? • R,G,B components are correlated • Transmitting R,G,B components separately is redundant • More efficient use of bandwidth is desired • RGB->YC1C2 transformation • Decorrelating: Y,C1,C2 are uncorrelated • C1 and C2 require lower bandwidth • Y (luminance) component can be received by B/W TV sets Color transformation is a compromised solution, but the ultimate one

  6. Why YUV?

  7. Video Carrier Color Sub-Carrier Audio Sub-Carrier White level 100 Cr BW = 0.6 MHz Cb BW = 0.6 MHz Phase=241° 80 Phase=61° Cr BW = 1.3 MHz Cb BW = 0.6 MHz Phase=103° 60 0 3.58 MHz 4.5 MHz Phase=347° 40 Phase=167° Color burst Phase=0° 20 Black level IRE Phase=283° 0 Blank level Magenta -20 White Yellow Green Cyan Black Blue Red 9 cycles Sync level Backporch - 40 Visible Line Interval Blanking Interval Color Video Signal

  8. Analog Video Standards

  9. Analog Video Standards Ch’s

  10. 4:3 Aspect Ratio 16:9 Aspect Ratio Why Digital Television? • Digital carrier can transmit any digital content • The television content is sent as data • Revolutionary Change • Existing TV sets will not receive it • Totally separate physical plant

  11. Not great to begin with…

  12. Getting worse…

  13. Still worse…

  14. Yuck!

  15. The Digital TV Experience • Improved picture quality • Analog with weaker and weaker signals • Digital with weaker and weaker signals • Program guide information • Display depends on TV or receiver • Virtual channel numbers • Multicasting

  16. Picture stays like this until…

  17. it’s right on the borderline…

  18. and then it’s gone!

  19. Digital Television (DTV) • Three major standards for DTV: DVB (Europe), ATSC (U.S), and ISDB (Japan) • Analog Switch-off: (e.g. Netherlands (Dec 06), Belgium (Jan 2007), USA (Feb 09))

  20. Comparison of Classic Analogueand Modern Digital TV • Digital TV from the technological viewpoint enables: • Higher video quality (e.g. high-definition-TV) • Higher audio quality (e.g. 5.1 Dolby surround) • TV equipment is equipped with small-sized computer a-like software • Internet connection on TV-equipment • New content forms as known from the Internet (e.g. MPEG-4 support, HTML)

  21. Electronic Program Guide (EPG) Information Portal Pay-per-View (PpV) Video-on-Demand (VoD) Education Shopping Games Standard Internet Services Communication Community Services Government Health Finance and Banking Examples of Digital TV Value-Added Services - Overview

  22. DTV Formats • HDTV - High Definition TV – 720p vertical scanning lines or higher – 1920x1080 is true HDTV – 16:9 aspect ratio • EDTV - Enhanced Definition TV – 480p vertical scanning lines or higher – Aspect ratio not specified • SDTV - Standard Definition TV – Digital reception but can be less than EDTV resolution – Aspect ratio not specified

  23. DTV Broadcasting

  24. ATSC (USA)

  25. DVB (Europe)

  26. ISDB(Japan)

  27. Around the World Lähde: DVB

  28. MPEG-2 Data Streaming Type

  29. MPEG-2 Program Stream • Combines one or more Packetised Elementary Streams (PES), which have a common time-base, into a single stream • Designed for use in relatively error-free environments (e.g. digital storage) and suitable for applications which may involve software processing • Program stream packets may be of variable and relatively great length

  30. MPEG-2 Transport Stream • Combines one or more Packetised Elementary Streams (PES) with one or more independent time bases into a single stream (sometimes called multiplex) • Designed for use in environments where errors are likely, such as transmission in lossy or noisy media • The transport stream is made of packets with fixed length of 188 bytes

  31. System Layers layered system with header/descriptors 996 Mb/s 1920 x 1080 @60I Multiple Picture Formats and Frame Rates Picture Layer MPEG-2 video and Dolby AC-3 compression syntax Compression Layer Motion Vectors Data Headers Chroma and Luma DCT Coefficients Variable Length Codes Flexible delivery of data and future extensibility Packet Headers Transport Layer Aux data Video packet Audio packet Video packet MPEG-2 packets Terrestrial 19.3 Mb/s Transmission Layer 6 MHz Source:Sarnoff Corporation

  32. Different Programs

  33. PES to PT

  34. The Transport Stream Packet

  35. HDTV SDTV Data Null Different Resolution • DTV sends a stream of digital packets • >103,000 packets per second (188 bits/packet) • The packet header identifies the packet as High Definition TV, SDTV, MP3 files, Web pages, Databases or other content

  36. Streaming data • Digital Television is a 19.39 Mbps “pipe” • MPEG-2 native transport, but IP can be encapsulated • Bandwidth required for DTV varies from 3.5 Mbps to 19.39 Mbps • Data can use opportunistic to 15.9 Mbps • Rates will improve over time

  37. Ch. 12 Ch. 6 Ch. 10 Ch. 11 Ch. 7 Ch. 8 Ch. 9 6 Mhz 6 Mhz 6 Mhz 6 Mhz 6 Mhz 6 Mhz 6 Mhz Digital Station Analog Station Bandwidth • Digital Television uses the same RF propagation as analog TV • Same Radio Shack antenna will work

  38. How Does it Work? 19.4 Mbps High Definition

  39. How Does it Work? Standard Definition 19.4 Mbps High Definition

  40. How Does it Work? Multicast Program 5 Program 4 19.4 Mbps Program 3 Program 2 Program 1

  41. How Does it Work? Data Standard Definition 19.4 Mbps High Definition

  42. Part II: Broadcasting Studio Studio

  43. DVB History

  44. DVB Standard • DVB uses the MPEG-2 Transport Stream to carry it’s data • DVB has added some features in the MPEG-2 standard (the MPEG standard had a door open for future additions to the standard) • Can deliver to the home almost anything that can be digitized: • High Definition Television (HDTV) • Standard Definition Television (PAL / NTSC, SECAM) • New broadband multimedia data and interactive services

  45. DVB Sub-standards • There are several sub-standards of the DVB standard • DVB-S (Satellite) – using QPSK – 40 Mb/s • DVB-T (Terrestrial) – using OFDM – 24 Mb/s • DVB-C (Cable) – using QAM – 50 Mb/s • DVB-IPI (IPTV) – IP-based NW)

  46. DVB Advantages

  47. DVB Advantages

  48. DVB Disadvantages

  49. DVB Block Diagram To encode and compress television video stream Raw PAL TV signal would need 864 MBit/s! MPEG-2 reduces this to 2–8 MBit/s Packetized Elementary Streams (PES) Different data streams of each single TV channel Max. 64 KByte per packet

  50. DVB Block Diagram • Forward Error Correction (FEC) with Reed Solomon Code • Adds 16 Bytes to 188 Byte transport stream packets • Enables receiver to correct up to 8 destroyed bytes • Reed Solomon Decoder can set “Transport Error Indicator” to signal error condition to upper layers • Disadvantage: delays signal due to time necessary for FEC calculation and • error correction

More Related