Introduction to Broadband Multimedia Network Introduction to Multimedia 1
Introduction z Scope of Broadband z Multimedia Description z Why multimedia systems? z Classification of Media z Multimedia Systems z Data Stream Characteristics Introduction to Multimedia 2
BROADBAND Broadband Signifies : High Bandwidth • High Access speeds, 256 Kbps t o 100 Mbps • Huge Core bandwidth pipes, STM – 16 (SDH), Gig. E (MEN) and 2. 5 Gig. E (DWDM / CWDM) Multiple Converged Services • High Speed Data • Voice • Video
Multiple Definitions z Broadband The capability of supporting, in both the provider-to-consumer (downstream) and the consumer-to-provider (upstream) directions, a speed in excess of 200 kilobits per second (kbps) in the last mile FCC 1999 Telecommunications Act Deployment Report z “High-speed” Services with over 200 kbps capability in at least one direction. The term highspeed services includes advanced telecommunications capability z The International Telecommunications Union’s (ITU) defines broadband service as 1. 5 Mbps 07/26/04 Page - 4
Speed Equals Time Downloading the DVD Movie “The Matrix” 7. 8 GB 07/26/04 Page - 5
Where are We Connecting? New World (Wide Packets) Order Long Haul Intercontinental & Coast to Coast Over Fiber at 10 Gbps & up (Long Haul DWDM, SONET, ATM & Ethernet) Long Haul: Metro/ Access: LAN: 07/26/04 Metro Network: Intra City or Metro Network All over Fiber at 1 Gbps 10 Gbps (Short Haul DWDM, SONET, Gigabit Ethernet) Long Haul Metro/Access Network: Network connections to customer, Last Mile (Access Network: Fast & Gigabit Ethernet , T-1, DSL and Cable modems) Desktop to Desktop – Floor to Floor 10 Mbps 1 Gbps (Ethernet & ATM) Copyright © World Wide Packets 2002 their respective owners All trademarks and registered trademarks are the property of Page - 6
Technology Futures, Inc. (2001) z The typical household of 2015 subscribes to broadband service at 24 Mb/s to 100 Mb/s, z Small businesses will access the network at data rates up to 622 Mb/s. z Medium and large businesses will access the network directly with fiber at data rates from 2. 4 Gb/s to 40 Gb/s. z By 2015, most customers obtain voice and narrowband data service via wireless or Vo. IP on broadband channels. z In 2015, fiber dominates the outside plant, comprising 100% of the interoffice network, 97% of the feeder network, and 95% of the distribution network. 07/26/04 Page - 7
BROADBAND SERVICES Services Offered On Broadband : • Data Services • High Speed Internet Services • Point to Point and Point to Multi Point VPN Services • Web Hosting Applications • Walled garden (Internet on TV) • Voices Services • Audio Conference • Voice over IP (Vo. IP) • Video Services • Video Broadcast • Video on Demand • Video telephony • Online Gaming
BROADBAND SERVICES Services Offered on Broadband Web Hosting Multimedia Conference Video/Audio. On-Demand Video on PC Online Gaming Revenue Value-added Applications Value Add applications to boost revenues Basic Telecom Service Voice Internet Time
BROADBAND COMPONENTS User Access Core Backend Business Voice over IP IP VPN video communication Residential gaming NMS Server Access & Aggregation Network Core Network NMS Client Radius Server video Video Server Soft Switch
BROADBAND NETWORK ELEMENTS Network Elements – Technology Options User The Access • Corporate / SME / SOHO • Residential • Wired Access ( DSL, Cable, FTTH) • Wireless ( BWA, Wifi ) • The Media • Optical Fiber The Core • The Technology • SDH • CWDM / DWDM • ATM • Ethernet Backend • Authentication Server • Content Servers • Web Hosting Servers • Video Servers
BROADBAND NETWORK COMPONENTS Core Network Access FTTH 100 M STB Backend MPLS M/C 2 Fiber SM G. 652 Internet Dual Homed Ring Gig. E DSLAM Internet Gateway Router BBRAS • DNS • DHCP • AAA • Voice Services Server • Internet Data Services Server • TV/Video Services Servers
CORE NETWORK TECHNOLOGIES Broadband Core Technologies: Core Network: Architecture • Ring • Single Homing • Dual Homing • Mesh Technology • ATM / IP / Ethernet • SDH over CWDM / DWDM
RING ARCHITECTURE Advantage • Low Cost • Simple Architecture Disadvantage • Hub – Potential Single Point failure Target Application • Towards Access and Low Capacity Core Collector Ring Advantage • Highly Reliable • Disadvantage • High Cost Solution. Target Application • High Capacity Core 2 Fiber SM G. 652 Aggregation Ring Core Switch Single Homed Dual Homed
MESH ARCHITECTURE Advantages • Extremely Reliable • Protection against Equipment / Fiber failure Disadvantages • Very Complex and Costly to implement Target Application • Highest Tier in Core Dual-Homed Mesh Core Ring Mesh Network
CORE TECHNOLOGIES Technology Options on Core 1. 2. 3. ATM Backbone IP / Metro Ethernet SDH / CWDM / DWDM.
ATM BACKBONE Traditional ATM Backbone Core Benefits: 1. High deployment across the world 2. Stabilized Technology 3. Aggregation through multiple E 1’s or upto STM 16 rings. 4. Good for aggregating Higher bandwidths. Drawbacks: 1. ATM pvc uses 10% overheads 2. Higher Provisioning time.
ATM BACKBONE CORE DSLAM for Residential Internet Access– Traditional Way x. DSL RFC 1483 Bridged Access E STM 4/STM 16 FTTH 100 M A STM 4/STM 16 D Metro Ethernet LAN Switch STM 4/STM 16 RFC 1483 Bridged Access x. DSL ATM MESH B RFC 1483 Bridged Access Broadband RAS Internet
METRO ETHERNET CORE Metro Ethernet Core Benefits: 1. Deployment has started in Huge way across the world 2. Aggregation through Fast Ethernet or Gigabit Ethernet. 3. Highly recommended for high bandwidths requirements. Drawbacks: 1. Technology getting standardized 2. Limited support for VLAN’s. 3. Single broadcast domain.
BROADBAND TECHNOLOGIES & SERVICES DSLAM for Residential Internet Access– Next Generation x. DSL FE/Gig Ethernet Service Connectivity Provider FE/Gig Internet Gateway Router x. DSL IPDSLAM Broadband RAS
SDH / CWDM / DWDM CORE Inter-City Backbone Network Backbone ATM STM 1/STM 4 on ATM 2 Fiber SM G. 652 Metro Transport and Aggregation Network SDH STM 1/STM 4 on Sonet Core Switch Aggregation Ring (CWDM/DWDM) MPLS Gig. E DSLAM traffic going to the core through Metro Ethernet UNI Aggregation Node Internet Access Router Internet Gateway Router BBRAS SDH Network STM 1/4/16 x. DSL Ethernet UNI Internet • Voice Services Server • Internet Data Services Server • TV/Video Services Servers • DNS • DHCP • AAA
Network Topologies z A topology refers to the manner in which the cable is run to individual workstations on the network. y the configurations formed by the connections between devices on a local area network (LAN) or between two or more LANs z There are three basic network topologies (not counting variations thereon): the bus, the star, and the ring. z It is important to make a distinction between a topology and an architecture. y A topology is concerned with the physical arrangement of the network components. y In contrast, an architecture addresses the components themselves and how a system is structured (cable access methods, lower level protocols, topology, etc. ). An example of an architecture is 10 base. T Ethernet which typically uses the star topology.
Bus Topology z A bus topology connects each computer (node) to a single segment trunk. y A ‘trunk’ is a communication line, typically coax cable, that is referred to as the ‘bus. ’ The signal travels from one end of the bus to the other. y A terminator is required at each end to absorb the signal so it does not reflect back across the bus. z In a bus topology, signals are broadcast to all stations. Each computer checks the address on the signal (data frame) as it passes along the bus. If the signal’s address matches that of the computer, the computer processes the signal. If the address doesn’t match, the computer takes no action and the signal travels on down the bus. z Only one computer can ‘talk’ on a network at a time. A media access method (protocol) called CSMA/CD is used to handle the collisions that occur when two signals are placed on the wire at the same time. z The bus topology is passive. In other words, the computers on the bus simply ‘listen’ for a signal; they are not responsible for moving the signal along. z A bus topology is normally implemented with coaxial cable.
Bus Topology z Advantages of bus topology: y Easy to implement and extend y Well suited for temporary networks that must be set up in a hurry y Typically the cheapest topology to implement y Failure of one station does not affect others z Disadvantages of bus topology: y Difficult to administer/troubleshoot y Limited cable length and number of stations y A cable break can disable the entire network; no redundancy y Maintenance costs may be higher in the long run y Performance degrades as additional computers are added
Star Topology z All of the stations in a star topology are connected to a central unit called a hub. y The hub offers a common connection for all stations on the network. Each station has its own direct cable connection to the hub. In most cases, this means more cable is required than for a bus topology. However, this makes adding or moving computers a relatively easy task; simply plug them into a cable outlet on the wall. z If a cable is cut, it only affects the computer that was attached to it. This eliminates the single point of failure problem associated with the bus topology. (Unless, of course, the hub itself goes down. ) z Star topologies are normally implemented using twisted pair cable, specifically unshielded twisted pair (UTP). The star topology is probably the most common form of network topology currently in use.
Star Topology z Advantages of star topology: y. Easy to add new stations y. Easy to monitor and troubleshoot y. Can accommodate different wiring z Disadvantages of star topology: y. Failure of hub cripples attached stations y. More cable required (more expensive to wire a building for networking)
Ring Topology z A ring topology consists of a set of stations connected serially by cable. In other words, it’s a circle or ring of computers. There are no terminated ends to the cable; the signal travels around the circle in a clockwise (or anticlockwise) direction. z Note that while this topology functions logically as ring, it is physically wired as a star. The central connector is not called a hub but a Multistation Access Unit or MAU. (Don’t confuse a Token Ring MAU with a ‘Media Adapter Unit’ which is actually a transceiver. ) z Under the ring concept, a signal is transferred sequentially via a "token" from one station to the next. When a station wants to transmit, it "grabs" the token, attaches data and an address to it, and then sends it around the ring. The token travels along the ring until it reaches the destination address. The receiving computer acknowledges receipt with a return message to the sender. The sender then releases the token for use by another computer. z Each station on the ring has equal access but only one station can talk at a time.
Ring Topology z In contrast to the ‘passive’ topology of the bus, the ring employs an ‘active’ topology. Each station repeats or ’boosts’ the signal before passing it on to the next station. z Rings are normally implemented using twisted pair or fiber-optic cable z Advantages of ring topology: y Growth of system has minimal impact on performance y All stations have equal access z Disadvantages of ring topology: y Most expensive topology y Failure of one computer may impact others y Complex
What’s “New Generation Network” or NWGN? Examples: Next Generations New Generation Network (NWGN) Cell Phones > 2 G > 3 G > 4 G? Internet > IPv 4 > IPv 6 > IPv? Revised NXGN New Generations 1) clean-slate 2) modification Past Network Present Network 2005 Next Generation Network (NXGN) 2010 2015
Broadband in Indonesia Introduction to Multimedia 30
From Agricultural to Conceptual sps 08042010 31
The Information Revolution, Driver of the Knowledge Economy in a Global World 32
ROLE OF BROADBAND "for every one percentage point increase in broadband penetration in a state, employment is projected to increase by 0. 2 to 0. 3 percent per year” (brooking institute) 33
ROLE OF BROADBAND § § Broadband needs to be considered as basic national infrastructure, as it will fundamentally reshape the world in the 21 st century and change the way services are delivered – from e-health to e-education to e-commerce to egovernment. Broadband is the most powerful tool ever devised to drive social and economic development, and accelerate progress towards the Millennium Development Goals. Broadband is becoming a prerequisite to economic opportunity for individuals, small businesses and communities. Those without broadband the skills to use broadband-enabled technologies are becoming more isolated from the modern American economy. Broadband can provide significant benefits to the next generation of entrepreneurs and small businesses—the engines of job creation and economic growth for the country. 34
BROADBAND & SMEs § It § § allows small businesses to achieve operational scale more quickly. Broadband associated ICTs can help lower company start-up costs through faster business registration and improved access to customers and suppliers. It gives SMEs access to new markets and opportunities by lowering the barriers of physical scale and allowing them to compete for customers who previously turned exclusively to larger suppliers. It allow small businesses to increase efficiency, improve market access, reduce costs and increase the speed of both transactions and interactions. E-commerce solutions eliminate geographic barriers to getting a business's message and product out to a broad audience. 60 million Americans go online every day to find a product or service, but only 24% of small businesses use e-commerce applications to sell online 35
BROADBAND & ECONOMIC SECTORS z OECD report urges governments to invest in open-access high-speed national fiber networks that can serve as the future delivery mechanism for a huge range of new and innovative public sector services. z And despite the large initial capital investment needed – typically US$ 1, 5002, 500 per household connected – the report shows that National Broadband Networks can pay for themselves within ten years, through dramatic savings in just four key economic sectors: z electricity z healthcare z road transport z Education z cost savings across the four sectors of just 0. 5%-1. 5% would be sufficient to justify the cost of laying high-speed fiber-to-thehome via a national point-to-point network. 36
The Positive Side of Indonesian ICT Development Mobile and Internet Tariffs are among the cheapest in SE Asia Large growths in Mobile Subscribers for several years The growing applications and contents in Internet and Mobile services, such as IP-TV, streaming videos, games, entertainments, Black. Berry, etc. Indonesia is among the World's largest users of Web 2. 0 Social Networking, such as Blogs, Facebook, Multiply, Youtube, YM, Chatting, etc 37
The Negative Side of the Indonesian ICT Development z The declining profit margins of Operators due to very intense tariff competition z The lowering of Quality of Service, especially 3 G and mobile Internet services z Low or little profits from Web, Internet and Social Networks, due to average low income of Indonesians z ICT growth has not been accompanied by economic growth; little value added results 38
ICT Indicators 2004 -2008 Population in 2008 = 228, 523, 300 Households in 2008 = 57, 716, 100 Income per Capita = Rp 7. 5 millions PDB per Capita = Rp 8. 7 millions per year % of Households with Fixed Phones = 12. 69% (24. 51% in cities, 3. 72% in villages) 39
INFRASTRUKTUR DATA 2008 INDONESIA (UN E-Gov Survey 2008) Internet / 100 Users 7. 18 PC / 100 Users 1. 47 Cellular Subs /100 users 28. 30 Main Telephone Lines/100 Users 6. 57 Broadband / 100 Users 0. 05 40
E-Readiness Peringkat Kesiapan Teknologi 2008 -2009 Negara (Sumber: Global Competitiveness Report 2008 -2009, World Economic Forum) Thailand 34 66 Teknologi Maju 50 Indonesia 55 88 Vietnam 70 Philipina Daya Saing Teknologi Daya Serap Teknologi Regulasi TIK FDI dan Transfer Teknologi Jasa Seluler Pengguna Jumlah Broad. Internet Komputer band 61 61 48 72 78 72 94 61 65 71 24 100 107 105 100 79 71 54 72 57 114 70 63 79 71 70 52 49 60 50 84 101 70 96 Sri Lanka 77 82 54 45 59 47 102 117 94 98 Kamboja 109 123 109 106 122 94 120 130 128 108 e-Readiness 2008 (Sumber: The Economist Intelligence Unit, 2007) Negara Thailand Philipina Sri Lanka Vietnam Indonesia Peringkat Nilai Total Akses Bisnis Sos Bud Hukum Kebijakan 47 55 60 65 68 5, 22 4, 90 4, 35 4, 03 3, 59 3, 80 3, 20 2, 95 2, 25 2, 30 6, 99 6, 56 5, 80 6, 31 6, 49 5, 07 4, 53 4, 80 3, 53 5, 90 4, 50 6, 30 4, 40 3, 20 5, 25 5, 20 4, 10 4, 60 3, 40 41 Adopsi Bisnis 5, 10 5, 45 3, 70 3, 75 3, 20 Sumber : RPJMN 2009 -2010
WHY FIXED BROADBAND ? § Mostly dedicated sampai ke last-miles § Wireless pada umumnya untuk low-traffic § Infrastruktur Dasar § Long-term investment § Public Private Partnership § Optimalisasi Pemanfaatan Palapa Ring § Industri Kreatif sangat membutuhkan 42
Multimedia Description z Multimedia xis an integration of continuous media (e. g. audio, video) and discrete media (e. g. text, graphics, images) through which digital information can be conveyed to the user in an appropriate way. y. Multi xmany, much, multiple y. Medium x. An interleaving substance through which something is transmitted or carried on Introduction to Multimedia 43
Why Multimedia Computing? y. Application driven xe. g. medicine, sports, entertainment, education y. Information can often be better represented using audio/video/animation rather than using text, images and graphics alone. y. Information is distributed using computer and telecommunication networks. y. Integration of multiple media places demands on xcomputation power xstorage requirements xnetworking requirements Introduction to Multimedia 44
Multimedia Information Systems z Technical challenges y. Sheer volume of data x. Need to manage huge volumes of data y. Timing requirements xamong components of data computation and communication. x. Must work internally with given timing constraints - real-time performance is required. y. Integration requirements xneed to process traditional media (text, images) as well as continuous media (audio/video). x. Media are not always independent of each other - synchronization among the media may be required. Introduction to Multimedia 45
High Data Volume of Multimedia Information Introduction to Multimedia 46
Technology Incentive z Growth in computational capacity x. MM workstations with audio/video processing capability x. Dramatic increase in CPU processing power x. Dedicated compression engines for audio, video etc. z Rise in storage capacity x. Large capacity disks (several gigabytes) x. Increase in storage bandwidth, e. g. disk array technology z Surge in available network bandwidth xhigh speed fiber optic networks - gigabit networks xfast packet switching technology Introduction to Multimedia 47
Application Areas z Residential Services xvideo-on-demand xvideo phone/conferencing systems xmultimedia home shopping (MM catalogs, product demos and presentation) xself-paced education z Business Services x. Corporate training x. Desktop MM conferencing, MM e-mail Introduction to Multimedia 48
Application Areas z Education x. Distance education - MM repository of class videos x. Access to digital MM libraries over high speed networks z Science and Technology xcomputational visualization and prototyping xastronomy, environmental science z Medicine x. Diagnosis and treatment - e. g. MM databases that provide support for queries on scanned images, X-rays, assessments, response etc. Introduction to Multimedia 49
Classification of Media y. Perception Medium x. How do humans perceive information in a computer? • Through seeing - text, images, video • Through hearing - music, noise, speech y. Representation Medium x. How is the computer information encoded? • Using formats for representing and information • ASCII(text), JPEG(image), MPEG(video) y. Presentation Medium x. Through which medium is information delivered by the computer or introduced into the computer? • Via I/O tools and devices • paper, screen, speakers (output media) • keyboard, mouse, camera, microphone (input media) Introduction to Multimedia 50
Classification of Media (cont. ) y. Storage Medium • Where will the information be stored? • Storage media - floppy disk, hard disk, tape, CD-ROM etc. y. Transmission Medium • Over what medium will the information be transmitted? • Using information carriers that enable continuous data transmission - networks • wire, coaxial cable, fiber optics y. Information Exchange Medium • Which information carrier will be used for information exchange between different places? • Direct transmission using computer networks • Combined use of storage and transmission media (e. g. electronic mail). Introduction to Multimedia 51
Media Concepts z Each medium defines x. Representation values - determine the information representation of different media • Continuous representation values (e. g. electro-magnetic waves) • Discrete representation values(e. g. text characters in digital form) x. Representation space determines the surrounding where the media are presented. • Visual representation space (e. g. paper, screen) • Acoustic representation space (e. g. stereo) Introduction to Multimedia 52
Media Concepts (cont. ) z Representation dimensions of a representation space are: y. Spatial dimensions: xtwo dimensional (2 D graphics) xthree dimensional (holography) y. Temporal dimensions: x. Time independent (document) - Discrete media • Information consists of a sequence of individual elements without a time component. x. Time dependent (movie) - Continuous media • Information is expressed not only by its individual value but also by its time of occurrence. Introduction to Multimedia 53
Multimedia Systems z Qualitative and quantitative evaluation of multimedia systems y. Combination of media xcontinuous and discrete. y. Levels of media-independence xsome media types (audio/video) may be tightly coupled, others may not. y. Computer supported integration xtiming, spatial and semantic synchronization y. Communication capability Introduction to Multimedia 54
Data Streams z Distributed multimedia communication systems xdata of discrete and continuous media are broken into individual units (packets) and transmitted. z Data Stream xsequence of individual packets that are transmitted in a timedependant fashion. x. Transmission of information carrying different media leads to data streams with varying features • Asynchronous • Synchronous • Isochronous Introduction to Multimedia 55
Data Stream Characteristics x. Asynchronous transmission mode • provides for communication with no time restriction • Packets reach receiver as quickly as possible, e. g. protocols for email transmission x. Synchronous transmission mode • defines a maximum end-to-end delay for each packet of a data stream. • May require intermediate storage • E. g. audio connection established over a network. x. Isochronous transmission mode • defines a maximum and a minimum end-to-end delay for each packet of a data stream. Delay jitter of individual packets is bounded. • E. g. transmission of video over a network. • Intermediate storage requirements reduced. Introduction to Multimedia 56
Data Stream Characteristics y. Data Stream characteristics for continuous media can be based on x. Time intervals between complete transmission of consecutive packets • Strongly periodic data streams - constant time interval • Weakly periodic data streams - periodic function with finite period. • Aperiodic data streams x. Data size - amount of consecutive packets • Strongly regular data streams - constant amount of data • Weakly regular data streams - varies periodically with time • Irregular data streams x. Continuity • Continuous data streams • Discrete data streams Introduction to Multimedia 57
Classification based on time intervals Strongly periodic data stream T Weakly periodic data stream T 1 T 2 T 3 T Aperiodic data stream T 1 T T 2 Introduction to Multimedia 58
Classification based on packet size Strongly regular data stream D 1 t T D 1 Weakly regular data stream Irregular data stream t t D 1 D 2 D 3 T D 1 D 2 D 3 Dn Introduction to Multimedia 59
Classification based on continuity Continuous data stream D 1 D 2 D 3 D 4 D Discrete data stream Introduction to Multimedia 60
Broadband Multimedia Communications Audio/Image/Video Representation Introduction to Multimedia 61
Introduction z Basic Sound Concepts z Computer Representation of Sound z Basic Image Concepts z Image Representation and Formats z Video Signal Representation z Color Encoding z Computer Video Format Introduction to Multimedia 62
Basic Sound Concepts z Acoustics xstudy of sound - generation, transmission and reception of sound waves. z Sound is produced by vibration of matter. x. During vibration, pressure variations are created in the surrounding air molecules. x. Pattern of oscillation creates a waveform • the wave is made up of pressure differences. x. Waveform repeats the same shape at intervals called a period. • Periodic sound sources - exhibit more periodicity, more musical - musical instruments, wind etc. • Aperiodic sound sources - less periodic - unpitched percussion, sneeze, cough. Introduction to Multimedia 63
Basic Sound Concepts z Sound Transmission x. Sound is transmitted by molecules bumping into each other. x. Sound is a continuous wave that travels through air. y. Sound is detected by measuring the pressure level at a point. y. Receiving x. Microphone in sound field moves according to the varying pressure exerted on it. x. Transducer converts energy into a voltage level (i. e. energy of another form - electrical energy) y. Sending x. Speaker transforms electrical energy into sound waves. Introduction to Multimedia 64
Frequency of a sound wave Frequency is the reciprocal value of the period. Air pressure period amplitude time Introduction to Multimedia 65
Basic Sound Concepts y. Wavelength is the distance travelled in one cycle x 20 Hz is 56 feet, 20 KHz is 0. 7 in. y. Frequency represents the number of periods in a second (measured in hertz, cycles/second). x. Frequency is the reciprocal value of the period. x. Human hearing frequency range: 20 Hz - 20 Khz, voice is about 500 Hz to 2 Khz. Infrasound from 0 - 20 Hz Human range from 20 Hz - 20 KHz Ultrasound from 20 k. Hz - 1 GHz Hypersound from 1 GHz - 10 THz Introduction to Multimedia 66
Basic Sound Concepts y. Amplitude of a sound is the measure of the displacement of the air pressure wave from its mean or quiescent state. y. Subjectively heard as loudness. Measured in decibels. 0 db - essentially no sound heard 35 db - quiet home 70 db - noisy street 120 db - discomfort Introduction to Multimedia 67
Computer Representation of Audio y. A transducer converts pressure to voltage levels. y. Convert analog signal into a digital stream by discrete sampling. x. Discretization both in time and amplitude (quantization). y. In a computer, we sample these values at intervals to get a vector of values. y. A computer measures the amplitude of the waveform at regular time intervals to produce a series of numbers (samples). Introduction to Multimedia 68
Computer Representation of Audio y. Sampling Rate: xrate at which a continuous wave is sampled (measured in Hertz) • CD standard - 44100 Hz, Telephone quality - 8000 Hz. x. Direct relationship between sampling rate, sound quality (fidelity) and storage space. x. Question • How often do you need to sample a signal to avoid losing information? x. Answer • To decide a sampling rate - must be aware of difference between playback rate and capturing(sampling) rate. • It depends on how fast the signal is changing. In reality - twice per cycle (follows from the Nyquist sampling theorem). Introduction to Multimedia 69
Sampling Sample Height samples Introduction to Multimedia 70
Nyquist Sampling Theorem y. If a signal f(t) is sampled at regular intervals of time and at a rate higher than twice the highest significant signal frequency, then the samples contain all the information of the original signal. y. Example x. Actual playback frequency for CD quality audio is 22050 Hz x. Because of Nyquist Theorem - we need to sample the signal twice, therefore sampling frequency is 44100 Hz. Introduction to Multimedia 71
Data Rate of a Channel y. Noiseless Channel • Nyquist proved that if any arbitrary signal has been run through a low pass filter of bandwidth H, the filtered signal can be completely reconstructed by making only 2 H (exact) samples per second. If the signal consists of V discrete levels, Nyquist’s theorem states: max datarate = 2 *H log_2 V bits/sec • noiseless 3 k. Hz channel with quantization level 1 bit cannot transmit binary signal at a rate exceeding 6000 bits per second. y. Noisy Channel • Thermal noise present is measured by the ratio of the signal power S to the noise power N (signal-to-noise ratio S/N). • Max datarate - H log_2 (1+S/N) Introduction to Multimedia 72
Quantization y. Sample precision - the resolution of a sample value y. Quantization depends on the number of bits used measuring the height of the waveform. y 16 bit CD quality quantization results in 64 K values. y. Audio formats are described by sample rate and quantization. • Voice quality - 8 bit quantization, 8000 Hz mono(8 Kbytes/sec) • 22 k. Hz 8 -bit mono (22 k. Bytes/s) and stereo (44 Kbytes/sec) • CD quality - 16 bit quantization, 44100 Hz linear stereo (196 Kbytes/s) Introduction to Multimedia 73
Quantization and Sampling Sample Height 0. 75 0. 25 samples Introduction to Multimedia 74
Audio Formats y. Audio formats are characterized by four parameters x. Sample rate: Sampling frequency x. Encoding: audio data representation • -law encoding corresponds to CCITT G. 711 - standard for voice data in telephone companies in USA, Canada, Japan • A-law encoding - used for telephony elsewhere. • A-law and -law are sampled at 8000 samples/second with precision of 12 bits, compressed to 8 -bit samples. • Linear Pulse Code Modulation(PCM) - uncompressed audio where samples are proportional to audio signal voltage. x. Precision: number of bits used to store audio sample • -law and A-law - 8 bit precision, PCM can be stored at various precisions, 16 bit PCM is common. x. Channel: Multiple channels of audio may be interleaved at sample boundaries. Introduction to Multimedia 75
Audio Formats z Available on UNIX yau (SUN file format), wav (Microsoft RIFF/waveformat), al (raw a-law), u (raw u-law)… z Available on Windows-based systems (RIFF formats) ywav, midi (file format for standard MIDI files), avi z RIFF (Resource Interchange File Format) ytagged file format (similar to TIFF). . Allows multiple applications to read files in RIFF format z Real. Audio, MP 3 (MPEG Audio Layer 3) Introduction to Multimedia 76
Computer Representation of Voice z Best known technique for voice digitization is pulse-code-modulation (PCM). y. Consists of the 2 step process of sampling and quantization. y. Based on the sampling theorem. x. If voice data are limited to 4000 Hz, then PCM samples 8000 samples per second which is sufficient for input voice signal. y. PCM provides analog samples which must be converted to digital representation. x. Each of these analog samples must be assigned a binary code. Each sample is approximated by being quantized. Introduction to Multimedia 77
Computer Representation of Music y. MIDI (Music Instrument Digital Interface) xstandard that manufacturers of musical instruments use so that instruments can communicate musical information via computers. x. The MIDI interface consists of: • Hardware - physical connection b/w instruments, specifies a MIDI port (plugs into computers serial port) and a MIDI cable. • Data format - has instrument specification, notion of beginning and end of note, frequency and sound volume. Data grouped into MIDI messages that specify a musical event. • An instrument that satisfies both is a MIDI device (e. g. synthesizer) x. MIDI software applications include • music recording and performance applications, musical notations and printing applications, music education etc. Introduction to Multimedia 78
Computer Representation of Speech x. Human ear is most sensitive in the range 600 Hz to 6000 Hz. x. Speech Generation • real-time signal generation allows transformation of text into speech without lengthy processing • Limited vs. large vocabulary (depends on application) • Must be understandable, must sound natural x. Speech Analysis • Identification and Verification - recognize speakers using acoustic fingerprint • Recognition and Understanding - analyze what has been said • How something was said - used in lie detectors. x. Speech transmission - coding, recognition and synthesis methods - achieve minimal data rate for a given quality. Introduction to Multimedia 79
Basic Concepts (Digital Image Representation) y. An image is a spatial representation of an object, a 2 D or 3 D scene etc. y. Abstractly, an image is a continuous function defining a rectangular region of a plane xintensity image - proportional to radiant energy received by a sensor/detector xrange image - line of sight distance from sensor position. y. An image can be thought of as a function with resulting values of the light intensity at each point over a planar region. Introduction to Multimedia 80
Digital Image Representation y. For computer representation, function (e. g. intensity) must be sampled at discrete intervals. x. Sampling quantizes the intensity values into discrete intervals. • Points at which an image is sampled are called picture elements or pixels. • Resolution specifies the distance between points - accuracy. x. A digital image is represented by a matrix of numeric values each representing a quantized intensity value. • I(r, c) - intensity value at position corresponding to row r and column c of the matrix. • Intensity value can be represented by bits for black and white images (binary valued images), 8 bits for monochrome imagery to encode color or grayscale levels, 24 bit (color-RGB). Introduction to Multimedia 81
Image Formats y. Captured Image Format xformat obtained from an image frame grabber x. Important parameters • Spatial resolution (pixels X pixels) • Color encoding (quantization level of a pixel - 8 -bit, 24 -bit) • e. g. “Sun. Video” Video digitizer board allows pictures of 320 by 240 pixels with 8 -bit grayscale or color resolution. Parallax-X video includes resolution of 640 X 480 pixels and 24 -bit frame buffer. Introduction to Multimedia 82
Image Formats y. Stored Image Format - format when images are stored y. Images are stored as 2 D array of values where each value represents the data associated with a pixel in the image. x. Bitmap - this value is a binary digit x. For a color image - this value may be a collection of • 3 values that represent intensities of RGB component at that pixel, 3 numbers that are indices to table of RGB intensities, index to some color data structure etc. y. Image file formats include - GIF (Graphical Interchange Format) , X 11 bitmap, Postscript, JPEG, TIFF Introduction to Multimedia 83
Basic Concepts (Video Representation) y. Human eye views video ximmanent properties of the eye determine essential conditions related to video systems. y. Video signal representation consists of 3 aspects: x. Visual Representation • objective is to offer the viewer a sense of presence in the scene and of participation in the events portrayed. x. Transmission • Video signals are transmitted to the receiver through a single television channel x. Digitalization • analog to digital conversion, sampling of gray(color) level, quantization. Introduction to Multimedia 84
Visual Representation y. The televised image should convey the spatial and temporal content of the scene x. Vertical detail and viewing distance • Aspect ratio: ratio of picture width and height (4/3 = 1. 33 is the conventional aspect ratio). • Viewing angle = viewing distance/picture height x. Horizontal detail and picture width • Picture width (conventional TV service ) - 4/3 * picture height x. Total detail content of the image • Number of pixels presented separately in the picture height = vertical resolution • Number of pixels in the picture width = vertical resolution*aspect ratio • product equals total number of picture elements in the image. Introduction to Multimedia 85
Visual Representation x. Perception of Depth • In natural vision, this is determined by angular separation of images received by the two eyes of the viewer • In the flat image of TV, focal length of lenses and changes in depth of focus in a camera influence depth perception. x. Luminance and Chrominance • Color-vision - achieved through 3 signals, proportional to the relative intensities of RED, GREEN and BLUE. • Color encoding during transmission uses one LUMINANCE and two CHROMINANCE signals x. Temporal Aspect of Resolution • Motion resolution is a rapid succession of slightly different frames. For visual reality, repetition rate must be high enough (a) to guarantee smooth motion and (b) persistance of vision extends over interval between flashes(light cutoff b/w frames). Introduction to Multimedia 86
Visual Representation x. Continuity of motion • Motion continuity is achieved at a minimal 15 frames per second; is good at 30 frames/sec; some technologies allow 60 frames/sec. • NTSC standard provides 30 frames/sec - 29. 97 Hz repetition rate. • PAL standard provides 25 frames/sec with 25 Hz repetition rate. x. Flicker effect • Flicker effect is a periodic fluctuation of brightness perception. To avoid this effect, we need 50 refresh cycles/sec. Display devices have a display refresh buffer for this. x. Temporal aspect of video bandwidth • depends on rate of the visual system to scan pixels and on human eye scanning capabilities. Introduction to Multimedia 87
Transmission (NTSC) y. Video bandwidth is computed as follows x 700/2 pixels per line X 525 lines per picture X 30 pictures per second x. Visible number of lines is 480. y. Intermediate delay between frames is x 1000 ms/30 fps = 33. 3 ms y. Display time per line is x 33. 3 ms/525 lines = 63. 4 microseconds y. The transmitted signal is a composite signal xconsists of 4. 2 Mhz for the basic signal and 5 Mhz for the color, intensity and synchronization information. Introduction to Multimedia 88
Color Encoding y. A camera creates three signals x. RGB (red, green and blue) y. For transmission of the visual signal, we use three signals • 1 luminance (brightness-basic signal) and 2 chrominance (color signals). x. In NTSC, luminance and chrominance are interleaved x. Goal at receiver • separate luminance from chrominance components • avoid interference between them prior to recovery of primary color signals for display. Introduction to Multimedia 89
Color Encoding y. RGB signal - for separate signal coding xconsists of 3 separate signals for red, green and blue colors. Other colors are coded as a combination of primary color. (R+G+B = 1) --> neutral white color. y. YUV signal xseparate brightness (luminance) component Y and xcolor information (2 chrominance signals U and V) • Y = 0. 3 R + 0. 59 G + 0. 11 B • U = (B-Y) * 0. 493 • V = (R-Y) * 0. 877 x. Resolution of the luminance component is more important than U, V x. Coding ratio of Y, U, V is 4: 2: 2 Introduction to Multimedia 90
Color Encoding(cont. ) y. YIQ signal xsimilar to YUV - used by NTSC format • Y = 0. 3 R + 0. 59 G + 0. 11 B • U = 0. 60 R - 0. 28 G + 0. 32 B • V = 0. 21 R -0. 52 g + 0. 31 B y. Composite signal x. All information is composed into one signal x. To decode, need modulation methods for eliminating interference b/w luminance and chrominance components. Introduction to Multimedia 91
Digitization y. Refers to sampling the gray/color level in the picture at MXN array of points. y. Once points are sampled, they are quantized into pixels • sampled value is mapped into an integer • quantization level is dependent on number of bits used to represent resulting integer, e. g. 8 bits per pixel or 24 bits per pixel. y. Need to create motion when digitizing video xdigitize pictures in time xobtain sequence of digital images per second to approximate analog motion video. Introduction to Multimedia 92
Computer Video Format y. Video Digitizer x. A/D converter y. Important parameters resulting from a digitizer • digital image resolution • quantization • frame rate x. E. g. Parallax X Video - camera takes the NTSC signal and the video board digitizes it. Resulting video has • 640 X 480 pixels spatial resolution • 24 bits per pixel resolution • 20 fps (lower image resolution - more fps) x. Output of digital video goes to raster displays with large video RAM memories. • Color lookup table used for presentation of color Introduction to Multimedia 93
Digital Transmission Bandwidth y. Bandwidth requirement for images xraw image transmission b/w = size of image = spatial resolution x pixel resolution xcompressed image - depends on compression scheme xsymbolic image transmission b/w = size of instructions and primitives carrying graphics variables y. Bandwidth requirement for video xuncompressed video = image size X frame rate xcompressed video - depends on compression scheme xe. g HDTV quality video uncompressed - 345. 6 Mbps, compressed using MPEG (34 Mbps with some loss of quality). Introduction to Multimedia 94
Broadband Multimedia Communications Multimedia Compression Techniques Introduction to Multimedia 95
Introduction y. Coding Requirements y. Entropy Encoding x. Content Dependent Coding • Run-length Coding • Diatomic Coding x. Statistical Encoding • Huffman Coding • Arithmetic Coding y. Source Encoding x. Predictive Coding • Differential Pulse Code Modulation • Delta Modulation y. Adaptive Encoding Introduction to Multimedia 96
Coding Requirements y. Storage Requirements x. Uncompressed audio: • 8 Khz, 8 -bit quantization implies 64 Kbits to store per second x. CD quality audio: • 44. 1 Khz, 16 -bit quantization implies storing 705. 6 Kbits/sec x. PAL video format: • 640 X 480 pixels, 24 bit quantization, 25 fps, implies storing 184, 320, 000 bits/sec = 23, 040, 000 bytes/sec y. Bandwidth Requirements xuncompressed audio: 64 Kbps x. CD quality audio: 705. 6 Kbps x. PAL video format: 184, 320, 000 bits/sec z COMPRESSION IS REQUIRED!!!!!!! Introduction to Multimedia 97
Coding Format Examples y. JPEG for still images y. H. 261/H. 263 for video conferencing, music and speech (dialog mode applications) y. MPEG-1, MPEG-2, MPEG-4 for audio/video playback, VOD (retrieval mode applications) y. DVI for still and continuous video applications (two modes of compression) • Presentation Level Video (PLV) - high quality compression, but very slow. Suitable for applications distributed on CD-ROMs • Real-time Video (RTV) - lower quality compression, but fast. Used in video conferencing applications. Introduction to Multimedia 98
Coding Requirements y. Dialog mode applications x. End-to-end Delay (EED) should not exceed 150 -200 ms x. Face-to-face application needs EED of 50 ms (including compression and decompression). y. Retrieval mode applications x. Fast-forward and rewind data retrieval with simultaneous display (e. g. fast search for information in a multimedia database). x. Random access to single images and audio frames, access time should be less than 0. 5 sec x. Decompression of images, video, audio - should not be linked to other data units - allows random access and editing Introduction to Multimedia 99
Coding Requirements y. Requirements for both dialog and retrieval mode applications x. Support for scalable video in different systems. x. Support for various audio and video rates. x. Synchronization of audio-video streams (lip synchronization) x. Economy of solutions • Compression in software implies cheaper, slower and low quality solution. • Compression in hardware implies expensive, faster and high quality solution. x. Compatibility • e. g. tutoring systems available on CD should run on different platforms. Introduction to Multimedia 100
Classification of Compression Techniques x. Entropy Coding • • • lossless encoding used regardless of media’s specific characteristics data taken as a simple digital sequence decompression process regenerates data completely e. g. run-length coding, Huffman coding, Arithmetic coding x. Source Coding • • lossy encoding takes into account the semantics of the data degree of compression depends on data content. E. g. content prediction technique - DPCM, delta modulation x. Hybrid Coding (used by most multimedia systems) • combine entropy with source encoding • E. g. JPEG, H. 263, DVI (RTV & PLV), MPEG-1, MPEG-2, MPEG-4 Introduction to Multimedia 101
Steps in Compression y. Picture preparation • • analog-to-digital conversion generation of appropriate digital representation image division into 8 X 8 blocks fix the number of bits per pixel y. Picture processing (compression algorithm) • transformation from time to frequency domain, e. g. DCT • motion vector computation for digital video. y. Quantization • Mapping real numbers to integers (reduction in precision). E. g. U-law encoding - 12 bits for real values, 8 bits for integer values y. Entropy coding • compress a sequential digital stream without loss. Introduction to Multimedia 102
Compression Steps Uncompressed Picture Preparation Picture Processing Adaptive Feedback Loop Quantization Compressed Picture Entropy Coding Introduction to Multimedia 103
Types of compression z Symmetric Compression • Same time needed for decoding and encoding phases • Used for dialog mode applications z Asymmetric Compression • Compression process is performed once and enough time is available, hence compression can take longer. • Decompression is performed frequently and must be done fast. • Used for retrieval mode applications Introduction to Multimedia 104
Broadband Multimedia Communications JPEG Compression 105
Introduction y. Requirements on JPEG implementations y. JPEG Image Preparation • Blocks, Minimum Coded Units (MCU) y. JPEG Image Processing • Discrete Cosine Transformation (DCT) y. JPEG Quantization • Quantization Tables y. JPEG Entropy Encoding • Run-length Coding/Huffman Encoding Introduction to Multimedia 106
Additional Requirements JPEG y. JPEG implementation is independent of image size and applicable to any image and pixel aspect ratio. y. Image content may be of any complexity (with any statistical characteristics). y. JPEG should achieve very good compression ratio and good quality image. y. From the processing complexity of a software solution point of view: JPEG should run on as many available platforms as possible. y. Sequential decoding (line-by-line) and progressive decoding (refinement of the whole image) should be possible. Introduction to Multimedia 107
Variants of Image Compression z Four different modes x. Lossy Sequential DCT based mode • Baseline process that must be supported by every JPEG implementation. x. Expanded Lossy DCT based mode • enhancements to baseline process x. Lossless mode • low compression ratio • allows perfect reconstruction of original image x. Hierarchical mode • accommodates images of different resolutions Introduction to Multimedia 108
JPEG Processing Steps Uncompressed Image Preparation Pixel, Block, MCU Image Preparation Prediction FDCT Baseline Sequential Mode Block, MCU 8 bits/pixel Transformation Source Coding lossy DCT Expanded Lossy Mode 12 bits/pixel Layered coding Lossless Mode Hierarchical Mode 2 -16 bits/pixel Predictive Entropy coding Switch between lossy DCT and lossless technique Quantization Compressed Image Entropy Encoding Run-length Huffman Arithmetic Run-length Huffman Introduction to Multimedia 109
Broadband Multimedia Communications MPEG Compression Introduction to Multimedia 110
Introduction y. General Information about MPEG y. MPEG/ Video Standard y. MPEG/ Audio Standard y. MPEG Systems • Multiplexing of Video/Audio Data Streams Introduction to Multimedia 111
General Information y. MPEG-1 achieves data compression of 1. 5 Mbps. x. This is the data rate of audio CD’s and DAT’s (Digital Audio Tapes). y. MPEG considers explicitly functionalities of other standards, e. g. it uses JPEG. y. MPEG defines standard video, audio coding and system data streams with synchronization. y. MPEG Core Technology • includes many different patents • MPEG committee sets technical standards Introduction to Multimedia 112
General Information (cont. ) y. MPEG stream provides more information than a data stream compressed according to the JPEG standard. x. Aspect Ratio - 14 aspect ratios can be encoded. • 1: 1 corresponds to computer graphics, 4: 3 corresponds to 702 X 575 pixels (TV format), 16: 9 corresponds to 625/525 (HDTV format). x. Refresh Frequency - 8 frequencies are encoded - • 23. 976 Hz, 24, 25, 29. 97, 50, 59. 94, 60 Hz. y. Other Issues with frame rate x. Each frame must be built within a maximum of 41. 7(33)ms to keep display rate of 24 fps(30 fps). x. No need or possibility of defining MCUs in MPEG. • Implies sequential non-interleaving order. x. For MPEG, there is no advantage to progressive display over sequential display. Introduction to Multimedia 113
MPEG Overview z MPEG exploits temporal (i. e frame-to-frame) redundancy present in all video sequences. z Two Categories: Intra-frame and inter-frame encoding y. DCT based compression for the reduction of spatial redundancy (similar to JPEG) y. Block-based motion compensation for exploiting temporal redundancy xcausal(predictive coding) - current picture is modeled as transformation of picture at some previous time xnon-causal (interpolative coding) - uses past and future reference Introduction to Multimedia 114
MPEG Image Preparation Motion Representation y. Predictive and interpolative coding x. Good compression but requires storage and information x. Often makes sense for parts of an image and not the whole image. y. Each image is divided into areas called macro-blocks (motion compensation units) x. Each macro-blocks is partitioned into 16 x 16 pixels for luminance, 8 x 8 for each of the chrominance components. x. Choice of macro-block size is a tradeoff between gain from motion compensation and cost of motion estimation. x. Macro-blocks are useful for compression based on motion estimation. Introduction to Multimedia 115
MPEG Video Processing y. MPEG stream includes 4 types of image coding for video processing x. I-frames - Intra-coded frames - access points for random access, yields moderate compression x. P-frames - Predictive-coded frames - encoded with reference to a previous I or P frame. x. B-frames - Bi-directionally predictive coded frames - encoded using previous/next I and P frame, maximum compression x. D-frames - DC coded frames y. Motivation for types of frames x. Demand for efficient coding scheme and fast random access x. Goal to achieve high compression rate - • temporal redundancies of subsequent pictures (i. e. interframes) must be exploited Introduction to Multimedia 116
MPEG Audio Encoding Steps Psychoacoustic Model Filter Bank Transformation from time to frequency domain 32 subbands Quantization Bit/noise Allocation If noise level is too high --> rough quantization is applied If noise level is too low --> finer quantization is applied Multiplexer Entropy Coder Compressed data Introduction to Multimedia Huffman Coding 117
MPEG/System Data Stream y. Video Stream is interleaved with audio. y. Video Stream consists of 6 layers x. Sequence layer x. Group of pictures layer • Video Param - width, height, aspect ratio, picture rate • Bitstream Param - bitrate, bufsize • QT - intracoded blocks, intercoded blocks x. Picture layer • Time code - hours, minutes, seconds x. Slice layer • Type - I, P, B • Buffer Param - decoder’s bufsize • Encode Param - indicates info about motion vectors x. Macro-block layer • Vertical Position - what line does this slice start on? • Qscale - how is the quantization table scaled in this slice? x. Block layer Introduction to Multimedia 118
Скачать презентацию Introduction to Broadband Multimedia Network Introduction to Multimedia
3914df200530bd33cfa802f8b7b1f256.ppt