HDTV on the Computer Science University: Experiences

INTRODUCTION No doubt, television (TV) is one of the most important discoveries in the history of mankind. Its beginnings are part of a broad period from the late nineteenth century until 1935. But it was not until July 1928 when it began issuing scanned images with a resolution of 48 lines on a regular basis, this was in the United States. In today's world of broadcast television technology is a revolution. Currently the most common digital terrestrial television (DTT), which offers higher quality in terms of image definition. This is the digital recording of the video signal, part of a conversion from analog to digital using a binary encoding process. This does not preclude you are thinking about a new global step in the evolution of Television: Digital Television High Definition (HDTV). HDTV promises to be the most important innovation since the introduction of color. Provide an image quality close to 35 mm film with multichannel sound. Although it is still a utopia for many countries, and some of them such as Japan and the United States, Canada, Spain implement this technology in some channels, in the case of Japan, this country has been working on HDTV for about 20 years, although began issuing signals of this type in 1990.

Cuba, although a country blockaded for more than 45 years, has never ruled out the possibility of developing according to its possibilities. As a result of this interest by the Cuban government, emerged in 2002 the University of Informatics Sciences (UCI) first university daughter of the Battle of Ideas. Since its inception, the UCI has pursued the goal of being the first digital city in the country with this foundation has worked to offer its students, teachers and workers in general a wide range of computer services, including a closed television system cable, which has contributed so much to recreation and leisure, as the development and quality of the teaching process. Television transmission in the ICU are carried out through a cable network that reaches all recipients of the University and also includes educational programming and informational programming on national television. The fundamental objective of the UCI Television is the dissemination of educational programs and teleclasses. Since the UCI takes the forefront of technological development in the country and HDTV today, is considered the future of broadcast television, has raised the need to begin to assess on the implementation of High Definition Digital TV network throughout the ICU.

This would allow to select which program to see a specific time offering users a highly interactive with the system, with a much higher quality in picture and sound to be mitigating the difficulties mentioned above. CHARACTER? STICA TECHNICAL Generally HDTV, high definition has had several formats and standards. All high-definition formats take the same aspect ratio as 16:9 widescreen, or need a widescreen TV (widescreen) to get all the benefits of high definition. There are two formats for High Definition Television: The format of 1920x1080i HD "Common Image Format? (HD-CIF) and High Definition 1280x720p "Progressive Image Sample Structure?. (1). The 1080i has 1080 active lines per frame and 1920 samples per active line and offers 2.07 million pixels in an image, the "i? the term is interlaced (interlaced). The interlaced mode reduces the demand for bandwidth. The lines are tracked alternately 60 times per second, is also called 1080i60, 1080i50 can be depending on the standard used. The number of back (60 or 50) is the frequency in Hertz (Hz) that is transmitted.

In this type of scanning each frame is displayed in two phases. During the first, are plotted every odd-numbered lines in 1 / 50 of seconds and the second lines are drawn in other even-numbered 1 / 50 seconds. A complete picture is drawn 25 times per second. (1) The 720p format provides 720 active lines per frame and 1280 samples per line, provides 921,000 pixels for images. The "p? comes from the progressive (progressive). In a progressive scan system passed all the pixels in each box scanning sequence that would be 1 / 50 seconds, or the whole picture is refreshed every time. This format is easier to compress and leads to lower bit rates, plus it has less interference with the 1080i image. (1). As seen above, the digital signal must go through a process of compression, this means before sending coding and decoding at the receiver to view it. For this the HDTV uses standards-based techniques, the most widely used is the MPEG world, this comparison between two images so that they can be transmitted over the network and uses the first image as reference (called I-frame) by sending only the parts of the images below (called B and P-frame) that differ from the original image.

The network viewing station rebuild all images based on the reference image and the different data contained in the B and P-frame. MPEG includes parameters such as prediction of motion in a scene and identifying objects. Among the standards that make up this family are MPEG-1, MPEG-2 and MPEG-4. (2). High definition is the best changes that has been provided in the history of the transmission of moving images. Image capture and display, mixed with encryption techniques and digital transmission, provide an image resolution four times better than standard television. The latter is based on a 450,000 pixel screen that contains approximately 25 to 30 displayed frames per second. High definition can have up to 2 million pixels seen at 24, 25 or 30 frames per second or 1 million views at 50 or 60 frames per second. DESCRIPTION OF TELEVISION SYSTEM IN THE ICU ICU Today is running a cable TV that comes close to each recipient of the University. Besides, it offers the service of Inter-us, which publishes teleclasses, series, movies.

This service is supported on the data network and plays an important role in the development of university life and teaching of the UCI. The data network available to the University is quite fast, considering the large number of users and services that it supports, but they are working on it more efficient. There is fiber optic backbone across the main, also between the floors of the buildings and residence for the fiber from the node is used to level 2 step ladder. Inside the premises is generally used UTP (Unshielded Twisted Pair English). It is a LAN (Local Area Network) defined by the interconnection of several computers and peripherals. Its most widespread application is the interconnection of personal computers and workstations in offices, classrooms, etc.. There is a central node that manages the other subnodes dividing the main component subnets and these in turn in other less complex forming a star topology. These subnets are:? Area of ​​residence,? Area of ​​Teaching, IP, and Laboratories Old Rectory.

The TV system in the ICU was designed for 500 recipients, now has more than three thousand who receive supply from a single header line. Only added splitters and signal amplifiers, so the signal must travel longer distances and reach many more receptors with almost the same transmission equipment. As the analog signal is exposed to phenomena such as noise, interference, distortion and attenuation, which increases as it passes through amplifiers, they amplify the signal, but also the noise that this entails, therefore the more amplifiers are used worsens final signal quality. Besides this, there is the question that television is not interactive, ie you can not choose which program to see a particular time. With HDTV, all these phenomena mentioned above disappear because it is a digital signal. That's why this research has set itself the objective of determining the requirements for the implementation of High Definition Digital Television in the University data network, in order to make a contribution to the improvement of television broadcasts today are performed in the ICU, using the strengths offered by fiber optics and using that reaches all parts of the ICU.

This will be incorporating a new service that offers the wide range of data networking today with all the infrastructure created.

HDTV ON DATA NETWORK UNIVERSITY Generally, television services over data networks are provided with connecting service to the Internet via a broadband operator on the same infrastructure but with a reserved bandwidth. The fact that the transmitted signal is HD does not change this because it is still digital television. Its effectiveness is based on the compression standard is chosen to compress the signal so that the bandwidth required for transmission does not exceed the available bandwidth, but at the same time not compromised the quality of the video emits. Keep in mind also the needs of each of the types of channels. For the development of this work, transmission tests will be conducted by video streaming, live streaming either, released in a multicast and broadcast on-demand streaming unicast way. Unicast identifies the point to point communication, ie when there is only a single sender and a receiver. In the case of audio and video streaming requires high bandwidth if unicast is used, it should send the data packet to all receivers and this network collide if this number becomes too large, however is advised as unicast streaming services for VOD (Video on Demand), since the only way in which the user may have pauses and advances in the video you are viewing.

The problem of bandwidth is that the networks are limited in the amount of traffic they can afford. In the ICU the network is the most important service it supports email, chat, Internet access, etc. The bandwidth is closely related to the bitrate and transmission speed. The bitrate is only the bit rate, ie, the number of bits that are sent in a unit of time, this feature is often mitigated by the use of video and audio codec that eliminate image information and still not conflict with the video quality as these changes are invisible to the human eye. The transmission speed depends undoubtedly the bandwidth and bit the cup is being sent. Multicast is the ideal solution for live streaming, for thereby some packets are sent to special addresses that belong to specific multicast groups. These packets are sent to the multicast address of the network and hence are sent to different members of the group, recognizing packets that are of interest and accept them.

(3). The topology of a multicast group is like a tree, as the data source node and the branches reaching every group member. At the point where a branch divides is present in other router or router. The role of these devices is to copy or replicate these packets when passing through two or more interfaces on your way to reach members of the group. (4). In the ICU, is implemented using IGMP multicast to perform the above operations that compose it and make it usable in any environment where multicast is to be used. As a routing protocol is PIM-DM has chosen, the density is determined by taking into account the number of computers with multicast enabled compared to the total order of the institution. It is the most widely used routing protocol in the world in the way either scattered or dense. The preference for this technology because it offers huge advantages over analog TV, these are summarized below: By providing a high spatial resolution, it is possible that greater realism can be seen in a larger screen.

Paves the way toward a more computerized, as it allows TV-PC convergence. The TV can accept data from telecommunications services, providing a large number of services. Better quality of image and sound. The signal is robust against interference, noise and multipath. Allows reception at home easily and inexpensively. The reception can be portable or fewer movimiento.Uso of frequency can be used for single frequency networks. It requires less transmission power. Increase the number of programs with respect to the current television, promoting multiple programs and multimedia services in each radio channel. The multiplicity of channels possible to obtain surround sound audio as used in theaters and transmit different languages ​​with the same video program. (3) (7) HDTV is Digital TV variant provides more definition, which is why the DTV inherits many of the advantages this offers, in addition to providing higher quality in terms of image and sound. RRESULTADOS. REQUIREMENTS FOR THE IMPLEMENTATION OF THE UCI HDTV Once the tests carried ends, the first requirement to note is that the client machines must have at least 246 MB of RAM and a 2.40 GHz processor

The bandwidth needed to transmit high-definition video is usually larger than necessary to transmit TV in any other standard, to give an example: the bandwidth to transmit uncompressed HD video in 720p format is close to the 354 Mbps, 1080i and about 1.5 Gbps, these applications are only available for high speed networks such as Internet 2. Normally this video is compressed, in this thesis will be chosen to propose the H.264 codec based on research carried out in parallel to this, with issue: Proposal for a compression standard for HDTV in the assembly UCI. (6). The bitrate that the video must be compressed by the codec mentioned above must be between 4 Mbps and 6 Mbps, this to maintain a balance between image quality and consumption of bandwidth, in a way that does not influence an exaggerated on the bandwidth that is counted. According to measurements made possible to achieve this goal, could play video on the machines acted as clients and the percentage of occupied bandwidth for unicast and multicast flows never exceeded 20%, that is the occupied bandwidth was never greater than 20 Mbps

In the case where the PC is committed to a FTP copy process and performance chat did not exceed 50%. In the case of the measurement was done by distributing a video stream is unicast, to have a single client, the occupied bandwidth was close to 10 Mbps and has two clients at about 20 Mbps, according to these values can ensure that growth in the use of bandwidth to connect more customers to view the streaming will be at values ​​close to that obtained with one or two machines. Given this, when 100 users are connected to the bandwidth will be close to 1 Gbps, which is the bandwidth that comes today to switch residence buildings, because the apartments there is 100 Mbps So , to consist of approximately 7 000 computers this connection speed is not enough. The bandwidth required for effective transmission of HDTV depends on the compression format used and the audience you have. The standard most commonly used top competition in the world is the 1 to 10.

Using this rule we can calculate a simultaneous audience of 700 recipients in the ICU. It should be understood in this case, which have receptors for VOD as the 7 000 computers. The relevant calculations to calculate the required bandwidth for a unicast VOD are as follows: - Total PC: 7 000 - According to standard maximum concurrency: 700 simultaneously connected. - Value obtained in the tests (rounded): 10 Mbps for each client PC. Therefore: 700 x 10 Mbps = 7 000 7 000 Mbps Mbps / 1024 = 6.84 Gbps 7 Gbps. In this way we can say that if the unicast video streaming is implemented to be seen by the 10 000 recipients will need a server to 10 Gbps, and if it is implemented to be viewed by only 3 000 televisions will need a server to 3 Gbps. This solution will become much more feasible once you perform the implementation of Inter-us multiple servers in different locations of the University, which is planning to perform. On the other hand, the results obtained concerning the multicast traffic is far from the previous ones if we consider that in this test the maximum bandwidth obtained was 4.5 Mbps

What shows that it is possible to transmit multicast HDTV ICU once interconnection has teams that support IGMP for multicast traffic, as it was found that this is the best way to convey the HDTV data network. If we can meet these requirements, the authors of this paper ensure that it is possible to carry out the implementation of High Definition Digital Television in the ICU. Once implemented this technology, interactivity could be achieved teleconferences between the student and the teacher CONCLUSIONS Through this work we conducted a research on Digital Television and its use in the University, which would be of great importance to considerable improvement of the television service and with it the teleclass to give students and teachers. He distributed a High Definition signal at different locations in the ICU to perform technical tests on the behavior of network traffic data. This done, a thorough analysis of the results obtained to comply with the general objective of the research was to determine the requirements for the implementation of High Definition Digital Television at the University, including requirements to bandwidth transmission occupies a high definition signal on the network, the bitrate to be issued to the different videos without affecting the quality of the images are displayed without occupying a significant bandwidth, features that should have the equipment interconnection and the necessary specifications for the server that will be used to offer video on demand service.

At this point we laid the foundation for the development of this technology, which are known features as well as technical requirements, the ways in which can be transmitted and the possible formats for doing REFERENCES 1. High Definition. The Standards. Posted on: September 15, 2004 to arrange updated June 14, 2006, last update: September 15, 2004. [Accessed on: December 13, 2007]. Available at: www.hdtv.video-computer.com/2_Estandars_HDTV.htm.1 2. Digital Video Compression. published: August 2004 Last update: August 2004. [Accessed on: November 30, 2007]. Available at: www.axis.com / en / documentation / compresion_video_es.pdf. 3. Cejudo, J. F. B., Bermejo, D. F., et al. Digital Terrestrial Television. asenmac.com, [Accessed on: December 13, 2007]. 4. DOYLE, J. Understanding and Implementing Multicast Services. Juniper Networks, Inc., 2003. [Accessed on: March 10, 2008]. 5. Sebastian? N, F. J. I. Assessment as a server platform VideoLAN Video on Demand. [Accessed on: January 15, 2008]. Available at: Javier Izquierdo www.grc.upv.es/docencia/tdm/trabajos2007/Francisco Sebastián_vlcvod. pdf. 6. PEÑA., Y. D. and exit., N. P. Proposal for a compression standard for the installation of HDTV in the ICU. Tutor: Mr. Idelkys Q.

R. Working to qualify for the Diploma Engineering degree in Computer Science, University of Computer Science, 2008. Bibliography? A CONSULTATION 1. RICHARD A. MCMAHON, S. Introduction to Networks. Edited by: Services, E. Available at: http://biblioteca.uci.cu/titdigitales.htm # Tinfos. [Accessed on: June 8, 2008]. 2. STALLINGS, W. Communication and computer networks. Edited by: Hall, P. vol. 6th Edition, Available at: http://biblioteca.uci.cu/titdigitales.htm # Tinfos. [Accessed on: June 8, 2008].