FUTURE OF DIGITAL HOME NETWORKING HDTV Hussein Nazha SIKDER RAHMAN Team Work Siva Nazir Supervised By: Dr. Anil Fernando Aim The aim of this project to give its readers a view of the emerging TV technology “HDTV” and how to implement it in an Already existing “Home Network” Objectives To realize the merits of moving to a digitalized world To understand the features of HDTV and how it is different from Standard TV To understand the features of home networking and how it works To demonstrate how to introduce HDTV in home network Moving To a Digitalized World If you have looked at television sets at any of the big electronics retailers lately, you know that digital TV, or DTV, is a BIG deal right now in the United Kingdom. Most stores have whole areas devoted to digital TV sets. You will also hear a lot about four other topics: 1. HDTV and HDTV broadcasts 2. Digital satellite services 3. Digital cable 4. DVDs and DVD players Common Analog Televisions NTSC PAL SECAM Slow-Scan Television Narrow Bandwidth Television Common Digital Televisions Low Definition Television (LDTV) Standard Definition Television (SDTV) Enhanced Definition Television (EDTV) High Definition Television (HDTV) What is Feb. 17th, 2009 DTV Deadline Date? Congress passed a law on February 1, 2006, setting a final deadline for the DTV transition of February 17, 2009. Most television stations will continue broadcasting both analog and digital programming until February 17, 2009, when all analog broadcasting will stop. Analog TVs receiving over-the-air programming will still work after that date, but owners of these TVs will need to buy converter boxes to change digital broadcasts into analog format. Converter boxes will be available from consumer electronic products retailers at that time. Cable and satellite subscribers with analog TVs should contact their service providers about obtaining converter boxes for the DTV transition . What’s wrong with standard TV? Signal degradation Bandwidth limitation Low resolution Noise interference Lifeless sound system Limited screen view Solution HDTV! HDTV stands for High Definition Television It is a digital format  that provides an extremely high-resolution picture (2.1 million pixels), accompanied by digitally enhanced sound (Dolby Digital surround sound) all presented in widescreen (16:9 aspect ratio) HDTV refers to the TV itself and the broadcast method (over a digital network), and the way a particular show or movie is produced   Challenges….. Improving television with larger screens and better resolution requires a huge increase in transmission bit rates. The bit rates are limited by the available broadcast spectrum or network connection. So what is the solution? Compression.  MPEG 2 What is compression? Digital video data is encoded as a series of code words that causes the average length of the code words to be much smaller than would be the case. Provides extra algorithmic tools for efficiently coding video, supports a wide range of bit rates and provides for multi channel surround sound coding. Two key techniques employed in an MPEG codec. - Motion-compensated inter-frame prediction. - Intra-frame Discrete Cosine Transform (DCT) coding. Compression is achieved using the well known techniques Prediction. • motion estimation in the encoder • motion compensation in the decoder Discrete Cosine Transform (DCT). Quantization of DCT coefficients. Huffman encoding scheme. The whole process allows for great savings in terms of bit-rate ratio (>10:1) MPEG Coder / Decoder  Prediction The goal is to remove the redundancy to gain better compression ratios. Exploits temporal redundancy by predicting the frame to be coded from a previous 'reference' frame. The prediction can not be based on a source picture. Prediction has to be repeatable in the decoder How the prediction is done? Coder contains a local decoder which reconstructs pictures exactly as they would be in the decoder, from which predictions can be formed. Prediction Continues …. Prediction is done by storing pictures until the desired reference picture is available before encoding the "current" frames. The encoder can decide on a macro block basis to use forward prediction from a previous picture, backward prediction from a following picture. Interpolated prediction to minimize prediction error. The decoder must have two frame stores. Prediction Continues …. Discrete Cosine Transform It transforms a signal or image from the spatial domain to the frequency domain. An image is decomposed and then created by using set of basic functions. Helps to separate the image into parts of differing importance (with respect to the image's visual quality). Discrete Cosine Transform Continues…  • 64 pixel tile is converted into 64 frequency values. • Starting from the DC value the other 63 frequency values are scanned out in a zigzag pattern. • The encoder applies variable uniform quantization threshold to DCT coefficients to reduce the number of bits required to represent. Quantization High-frequency coefficients being more coarsely quantised than the low-frequency coefficients. All samples smaller than the threshold are cleared out to zero. Higher the threshold the higher the compression, but also the lower the image quality. Erasing smaller frequency values removes detail resolution in the images and also introduces image artifacts. Not acceptable for scientific or medical imaging Quantisation noise introduced by the coder is not reversible in the decoder, making the coding and decoding process 'lossy'. Huffman code Basically, it compresses the data by assigning codes with fewer bits to the most often encountered output patterns. An entropy code achieves the shortest average possible code word length for a source. Transmissions are highly sensitive to error propagation. Even a single bit error in the transmission can cause the image to break up into random noise until an error recovery code is detected. This produces very disturbing visual effects in noisy transmissions. Issues in HDTV 1. Bandwidth. - Conventional NTSC image bandwidth 3.35 MHz. - HDTV image needs bandwidth of 18 MHz. What limits this? - Current terrestrial channel allocations are limited to 6 MHz! What would be the Solution? - Change channel allocation system from 6 MHz to 20 MHz. - Compress signal to fit inside the 6 MHz existing bandwidth. - Allocate multiple channels for the HDTV signal. Issues in HDTV Continues …. 2. Interlaced versus non-interlaced - Kell factor Actual observed resolution is lesser than the vertical resolution promised by a TV system. For Progressive Scanning : about 70% of the maximum resolution. For Interlaced Scanning : Stationary Image : about 70% of the maximum resolution. Non Stationary Image: about 50% of the maximum resolution. Why? Due to the possibility of a picture element (pixel) falling "in- between" the scanning lines Issues in HDTV Continues ….  Benefits of HDTV A wider aspect ratio is a better match for movies. The normal American TV standard, called NTSC, uses a 4:3 aspect ratio, while HDTV provides for 16:9 The higher resolution of HDTV gives a more detailed and realistic picture With digital TV, you get CD quality sound, too - Dolby AC-3, also known as Dolby Digital 5.1. Benefits of HDTV Continue… Being digital, HDTV will eliminate noise and ghosting Accommodate more information within the same bandwidth used by standard TV Maintain the same quality as original Multicasting Comparison Table Home Networking Way of connecting the different electronic devices in a household by way of a local area network (LAN)  Application of home networking – Resource sharing – Communication – Home control – Home scheduling – Entertainment Technology Used in Home Networking Wired  – Ethernet – HomePNA or HPNA – Powerline Wireless  – Wireless Ethernet – HomeRF – Bluetooth Advantages and Disadvantages of Wired Technology Advantages: – Faster data transmission rate up to 100 Mbps – It is reliable and based on industry standard – HomePNA uses existing phone line so no extra wiring – Powerline use the home powerline also no need for extra wiring – Easy to install Disadvantages: – Ethernet involves new wiring so it is costly – Require hub, router, and server for intelligent networking – All the device must be connected to the wire to form the networking – Not flexible Advantages and Disadvantages of Wireless Technology Advantages: – As this is wireless so no wiring is required – It provides the mobility – It is flexible – Easy to install – Sometimes less expensive as no wiring is required Disadvantages: – Can have structural setbacks – It does not support long distange communication because of range problem – Bandwidth limitations – Can be very expensive Elements Needed for HDTV in Home Network Specialised HDTV antenna HDTV compatible set-top box Video distribution System Multimedia over coax  Issues to be Considered to Introduce HDTV in Home Networks Bandwidth Connectivity Structure Security Conclusion HDTV is here to change our watching experience It’s true that the costs for such TVs are high but eventually will drop as features continue to increase HDTV is a far superior media for delivering our television programs With HDTV broadcasts already underway, it is only a matter of a few years before HDTV technology is perfected and available in large doses References :http://www-scm.tees.ac.uk/users/a.clements/DSP/ADintro.htm :http://www.dtv.gov/consumercorner.html :http://www.fcc.gov/cgb/consumerfacts/digitaltv.html :http://forum.ecoustics.com/bbs/messages/34579/94121.html :http://columbiaisa.50megs.com/tv_hdtv_intro3.htm :http://www.digitaltvdesignline.com/howto/showArticle.jhtml?articleID=1 80207633 :www.zenith.com/sub_hdtv/mpeg_tutoril/codecdia1.HTM :http://www.bbc.co.uk/rd/pubs/papers/paper_14/paper_14.shtml :http://web.mit.edu/6.933/www/HDTV.pdf :http://www.eeproductcenter.com/showArticle.jhtml?articleID=17200191 :http://broadband.earthlink.net/home- networking/hardware/2wire/docs/2Wire_home_net_tutorial.html :http://compnetworking.about.com/od/homenetworking/ig/Home- Network-Diagrams/Wi-Fi-Router-Network-Diagram.htm :http://www.nwfolk.com/hdtv.html Questions!!!?
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