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Multimedia Technologies Integration Guide

Explore analog and digital video technologies, audio file technologies, Voice over IP, and assess bandwidth & throughput on a network. Learn how LANs and WANs are designed for multimedia applications and discuss future multimedia issues.

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Multimedia Technologies Integration Guide

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  1. Integrating Voice, Video,and Data Chapter 10

  2. Learning Objectives • Explain analog and digital video technologies • Describe audio file technologies • Explain audio and video sampling • Describe Voice over IP • Assess bandwidth and throughput on a network • Explain how multimedia transmissions work • Design LANs and WANs for multimedia applications • Discuss multimedia issues of the future

  3. Video Technologies • Roots in analog TV • Analog and digital video technologies • Main video technologies used on computers • Audio Video Interleave (AVI) • Moving Pictures Expert Group (MPEG) • Fractal image

  4. Analog Video • Primarily associated with television • Television broadcast standards • National Television Standards Committee (NTSC) • 525 vertical scan lines; 30 frames per second • Phase alternation line (PAL) • 625 vertical scan lines; 25 frames per second • System Electronique Couleur Avec Memoire (SECAM)

  5. Digital Video • Commonplace on the Internet • Increased distances • Sharper images • Network video transmissions involve several technologies; digital television uses one (MPEG-2)

  6. Video Compression Technologies • AVI • Interleaves video and audio data to be reproduced as short clips • MPEG • Standard set by the MPEG within the ISO • Fractal image compression • Uses properties of fractals, duplicated images, and mapping to compress frames

  7. Video Compression Techniques Used by MPEG • Lossy compression • Predicted encoding • Bidirectional interpolation

  8. Predicted Encoding

  9. Bidirectional Interpolation

  10. MPEG Levels

  11. MPEG VideoPlayback Options • Store on server for clients to download as a file and play using MPEG player software • Streaming the file over a network link

  12. Audio File Technologies • Algebraic-Code-Excited Linear Prediction (ACELP) • Audio Code Number 3 (AC-3), which is Dolby digital surround sound • Adaptive Differential Pulse Code Modulation (ADPCM) • Audio Interchange File Format (AIFF) continued…

  13. Audio File Technologies • Global System for Mobil Communication (GSM) • Interchange File Format (IFF) • Musical Instrument Digital Interface (MIDI) • MPEG-1 Audio • MPEG-2 Audio • MPEG-4 Audio • MPEG-7 Audio continued…

  14. Audio File Technologies • Open Document Architecture Audio Content Architecture (ODA ACA) • Pulse code modulation (PCM) • Sub-band adaptive differential pulse code modulation (SB-ADPCM) • Waveform audio file format (WAV)

  15. Audio File Technologies That Are Transported Over Networks • ACELP • Used in media player • MPEG • Used in many diverse kinds of applications • WAV (particularly PCM U-law) • Used to play music over the Internet

  16. Audio and Video Sampling • Samples of an analog signal taken at specific intervals construct a digital signal • Type of sampling technique influences the quality of the signal

  17. Popular Uses of Audio and Video Technologies • Internet radio and downloading music files • Audio and video conferencing • Online courses and seminars • E-mail attachments • Local and national news broadcasts

  18. Growth Trends for Audio and Video Technologies • Telephone messaging services • Seminars • Movies • Live out-of-classroom help from teachers • Interviews • Physician training about pharmaceutical products • Integration of telephone, TV, computer, and stereo • Wireless, handheld audio/video devices for visitors to a new city

  19. Voice over IP (VoIP) • Provides telephony communications over an IP network • Used by some companies as an alternative to PBXs, PAXs, and PABXs

  20. Devices on a VoIP Network • Telephone device • Converts voice sounds into binary, then into IP packets • Call processor or call server • Sets up and terminates calls • Manages a calling session • Translates telephone numbers or IDs into IP addresses • Specialized gateway • Converts IP packetized voice data into a signal that can be transmitted over a PSTN

  21. Widely Used VoIP Standards • ITU H.323 • Session Initiation Protocol (SIP) • Media Gateway Control Protocol (MGCP)/ MEGACO/H.248

  22. ITU H.323 • Outlines several types of devices for voice communications • Used with several accompanying standards for compression/decompression (codec) and voice communications handling

  23. SIP • Signaling protocol created by IETF • Used to start or stop a VoIP communications session • Uses commands modeled after HTTP • Uses URLs for addressing • Advantages • Can be used over the Internet or on an IP LAN, MAN, or WAN • Can be used with H.323 systems

  24. MGCP/MEGACO/H.248 • Designed to handle translation of an audio signal to a VoIP network • Relatively low overhead; uses UDP for audio communications over an IP network • Compatible with networks that use SIP

  25. Assessing Bandwidth and Throughput • Bandwidth • Transmission capacity of a communications medium • Typically measured in bits per second (data) or hertz (some data, voice, and video) • Determined by maximum minus minimum transmission capacity • Throughput • Amount of traffic passing through given point on network at given time

  26. Determining Download Time for a Single File • Download time in seconds = file size in bytes * 10 /connection speed in bps

  27. Factors That Affect Bandwidth and Throughput • File compression and file format compatibility • Synchronization • Latency • Jitter

  28. File Compression and File Format Compatibility • File compression • Reduces size of a normal file by using techniques to remove redundant information or blank areas in file’s structure

  29. Synchronization • Ensures all constituent pieces are assembled and played in the right order • Most reliable with adequate bandwidth

  30. Synchronization

  31. Latency • Time it takes for networked information to travel from transmitting device to receiving device • Influenced by: • Transmission delay • Propagation delay • Processing delay • Store-and-forward or switching delay

  32. Jitter • Presence of variable latency on a network • Causes evident reproduction errors • Clicks or pops in audio playback • Jerky or delayed response in video

  33. How Multimedia Transmissions Work in LANs and WANs • Typically occur between two devices (sender and receiver) with a LAN, WAN, or both in between • Different methods • Using network resources (eg, routers) • Creating transmissions that generate relatively more network traffic

  34. Transmission Types • Unicast • Broadcast • Multicast

  35. Unicast Transmissions

  36. Unicast Transmissions

  37. Broadcast Transmissions

  38. Broadcast Transmissions

  39. Multicast Transmissions

  40. Multicast Transmissions

  41. Multimedia Transmissions • Same application under different transmission methods • Role of Internet Group Management Protocol (IGMP) • Additional Protocols to Accommodate Multicasting • Distance Vector Multicast Routing Protocol (DVMRP) • Multicast Open Shortest Path First Protocol (MOSPF) • Protocol Independent Multicast (PIM)

  42. DVMRP • Works with RIP to determine: • Which workstations are subscribed to multimedia multicasts • Fewest hops to a particular router on a network • Route to take to reach a particular router

  43. MOSPF • Works like OSPF in finding the shortest path from source to destination for multicast transmissions

  44. PIM • Compatible with networks that use OSPF or RIP as their main routing protocol

  45. Protocols with Real-Time Streaming Multicasts • Real-Time Protocol (RTP) • Multicast protocol developed for real-time multimedia applications • Real-Time Transport Control Protocol (RTCP) • Works with RPT to provide specific controls over multicast transmissions • Provides management information

  46. Applications and Internetworking Devices • Resources Reservation Protocol (RSVP) • Used on TCP/IP-based networks • Enables an application to reserve computer and network resources it needs (bandwidth, buffers, maximum burst, classes of service) • Dynamically allocates resources as demands increase or decrease • Also know as the Resource Reservation Setup Protocol

  47. RSVP

  48. Making LANs and WANs Accommodate Multimedia Applications • Redesigning legacy networks for multimedia applications • Deploying high-speed Ethernet on multimedia-based LANs • Designing WANs that carry multimedia applications with ease

  49. Redesigning a Legacy Network • Add switches and routers

  50. Redesigning a Legacy Network

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