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Integrating Voice, Video, and Data

Integrating Voice, Video, and Data. Chapter 10. 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

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Integrating Voice, Video, and Data

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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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