HDTV

1. HDTV By: James Tosato & Jason Cerilli

2. DTV Current issue: the transition of analog TV, to digital. The full power analog TV stations will make full transition to 100% digital by June 12, 2009. As of February 17, 2009 one third of the broadcasting stations in the United States had already converted to digital signals. In Canada, by August 31st 2009 100% of all broadcasts must be in digital. Solution: for those who do not have digital TVs and rely on analog signals through antenna reception, they must purchase a digital converter box, which converts analog signals to digital. Why? Analog can only broadcast their signals using certain airwaves. Digital signals are more efficient, the broadcasting station can send several standard definition signals, or a high definition digital signals. This frees up the airwaves for wireless transmission and fire, police and other services. For more information please go to: http://www.crtc.gc.ca/ENG/INFO_SHT/BDT14.HTM http://www.dtv.gov/

3. Standards The introduction of the MPEG-1 compression standard provided the foundation for digital TV and spurred the development of modern TV standards worldwide. Today, the most important HDTV standards body is the Society of Motion Picture and Television Engineers. The group, recognized as the global leader in the development of standards and authoritative practices for film, television, video and multimedia, has defined the two most important standards: SMPTE 296M and SMPTE 274M. Basically, SMPTE 296M defines a resolution of 1280x720 pixels using progressive scanning, while SMPTE 274M defines a resolution of 1920x1080 pixels using either interlaced or progressive scanning. With digital compression methods such as MPEG-2 and H.264, the bandwidth for a single analog TV channel is enough to carry up to five regular digital TV channels, or up to two HDTV channels using progressive scanning.

4. Analog vs. Digital Signals Analog transmission: the signal is transmitted in a continuous signal that varies in amplitude. The signal can easily deteriorate. Digital transmission converts the analog television signal into a series of digital bits. Digital signals don't weaken with distance. No deterioration. Exact end-to-end reproduction, digital means better picture and sound quality, no matter what is broadcast.

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6. HDTV Sizes

7. Frame Size Frame size Frame size is defined as the number of horizontal pixels times the number of vertical pixels, e.g. 1280x720 or 1920x1080. The number of horizontal pixels is often omitted, since it is implied in the context. Therefore the different systems are usually referred to as 720 or 1080, combined with the letter i or p depending on what scanning method is used. Given that traditional television normally broadcasts in 704x576i or 704x480i, the visual information on an HDTV is two to five times larger.

8. Scanning: Interlaced vs. Progressive scan Interlaced scanning: this technique splits each frame into two fields. The scanning starts at the top-left corner and sweeps all the way to the bottom-right corner, skipping every alternate row on the way. Downsides: If objects are moving fast enough they will be in different positions when each individual field is captured. This may cause what is called motion artifacts. Another potential problem is called interline twitter. It is an effect that shows up when the subject being shot contains very fine vertical details that approach the horizontal resolution of the video format. Progressive scanning can eliminate some of these problems. This technique captures, transmits and displays all lines in the image in a single frame. Scanning is done line by line, from top to bottom. This takes away the flickering factor.

9. Application Example In a surveillance application, this can be critical for viewing details within a moving image such as a person running or a vehicle moving. This can be crucial if the material is, for instance, to be used as evidence in a court of law. Of course, these potential gains must be weighed against progressive scanning�s requirement for more bandwidth. At left, a full-sized JPEG image (704x576 pixels) from an analog camera using interlaced scanning. At right, a full-sized JPEG image (640x480 pixels) from an Axis network camera using progressive scan technology. Both cameras used the same type of lens and the speed of the car was the same at 20 km/h (15 mph). The background is clear in both images. However, the driver is clearly visible only in the image using progressive scan technology.

10. Frame rate Frame rate Frame rate is defined as the number of image frames per second (fps). For interlaced systems, the number often implies the field rate, which means the number usually is twice as high since there are two fields to every frame. Historically, one of the thornier issues had to do with a suitable frame/field refresh rate. Countries were divided into two camps � for reasons that very much depended on the frequency of the mains electrical supplies, which in turn affect image stability � favoring either 25/50 fps or 30/60 fps. Nonetheless both systems are compliant with HDTV and consequently also meet the full frame rate requirements of video surveillance.

11. Aspect Ratio Aspect ratio is the fractional relation of the width of a video image compared to its height. The two most common aspect ratios in home video are 4:3 (also known as 4x3, 1.33:1, or standard) and 16:9 (16x9, 1.78:1, or wide-screen). �squarish� 4:3 shape--only 33 perce nt wider than it was high. 16:9 is the native aspect ratio of most HDTV programming; it is 78 percent wider than it is tall, or fully one-third wider than 4:3.  wide-screen image offers a larger image, and the horizontal orientation of the human eyes

12. Decoding HDTV provides significantly better visual and audio resolution at the expense of higher bandwidth requirement and decoder cost. parallel decode processing is necessary to lower processing frequency. There are still many disadvantages. To avoid the problems described above, an HDTV decoder architecture based on efficient dual decoding paths with a block layer synchronized controller scheme and a writing back scheme.

13. Decoding cont. Overall Datapath Architecture Our dual decoder architecture. functionality and configuration of key units in this decoding system are briefly discussed as follows:

14. Block Diagram of the HDTV video decoder

15. Decoding cont�d controller algorithm. The flow chart of controller setting the demultiplexer

16. Decoding fixed schedule

17. Decoding write back scheme

18. MIPS topics Register set Assembler Pseudoinstructions Programs tend to be longer on RISC machines Instruction formats Arithmetic and Logic Instruction set Conditional branches Dealing with branch delays.

19. MIPS Architecture MIPS is one of the most popular RISC chips, used for example in SGI workstations and in a number of embedded applications. Every MIPS instruction is 32 bits, i.e. one word, in length. Register Set There are 32 general registers, named $0, $1, ..., $31. The assembler also has an alternate set of names for the registers, which show their suggested uses; here is a partial list: $0 zero contains the hard-wired constant 0 $1-$2 v0-v1 for expression evaluation and function return values $4-$7 a0-a3 for passing arguments $8-$15 t0-t7 for temporary results ... $28 gp pointer to global area $29 sp stack pointer $30 fp frame pointer (not used) $31 ra return address

20. MIPS instruction formats op op code rs register operand rt register operand rd register operand imm immediate constant shamt shift amount dist distance factor to branch (i.e. jump) target the formats are as follows. � I (�immediate�) format: � op: bits 31-26 � rs (source): bits 25-21 � rt (destination): bits 20-16 � imm: bits 15-0 � J (�jump�) format: � op: bits 31-26 � dist: bits 25-0 � R (�register�) format: � op: bits 31-26 � rs (source): bits 25-21 � rt (source): bits 20-16 � rd (destination): bits 15-11 � shamt: bits 10-6 � funct: bits 5-0 The shamt field is used if the instruction is to perform a right- or left-shift;

23. Storage and Compression Uncompressed 1080i HD 675GB/hour

24. Compression Decay Tiling Little colored blocks "mosquito noise"�

25. References http://www.design-reuse.com/news/7639/mips-architecture-hdtv-revolution.html http://www.design-reuse.com/news/exit/?id=7639&url=http://www.mips.com http://www.mips.com/products/product-materials/processor/mips-architecture/ http://www.hdtvfaq.org/hdtv-formats.html http://en.wikipedia.org/wiki/HDMI http://en.wikipedia.org/wiki/Digital_television http://electronics.howstuffworks.com/dtv.htm http://www.hardwaresecrets.com/article/283/2 http://www2.tku.edu.tw/~tkjse/2-2/2-2-1.pdf http://www.digitalhomedesignline.com/products/212200361 http://www.hardwaresecrets.com/article/283/2 http://tvs.consumerelectronicsnet.com/articles/viewarticle.jsp?id=127704