Download Lecture 10 - cda college

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
Design LANs and WANs for multimedia
applications
Discuss multimedia issues of the future
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
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)
Digital Video
Commonplace on the Internet
Increased distances
Sharper images
Network video transmissions involve
several technologies; digital television uses
one (MPEG-2)
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
Video Compression
Techniques Used by MPEG
Lossy compression
Predicted encoding
Bidirectional interpolation
Predicted Encoding
Bidirectional Interpolation
MPEG Levels
MPEG Video
Playback Options
Store on server for clients to download as a
file and play using MPEG player software
Streaming the file over a network link
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…
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…
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)
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
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
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
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
Voice over IP (VoIP)
Provides telephony communications over an
IP network
Used by some companies as an alternative
to PBXs, PAXs, and PABXs
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
Widely Used VoIP Standards
ITU H.323
Session Initiation Protocol (SIP)
Media Gateway Control Protocol (MGCP)/
MEGACO/H.248
ITU H.323
Outlines several types of devices for voice
communications
Used with several accompanying standards
for compression/decompression (codec) and
voice communications handling
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
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
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
Determining Download Time
for a Single File
Download time in seconds = file size in
bytes * 10 /connection speed in bps
Factors That Affect Bandwidth
and Throughput
File compression and file format
compatibility
Synchronization
Latency
Jitter
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
Synchronization
Ensures all constituent pieces are assembled
and played in the right order
Most reliable with adequate bandwidth
Synchronization
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
Jitter
Presence of variable latency on a network
Causes evident reproduction errors
Clicks or pops in audio playback
Jerky or delayed response in video
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
Transmission Types
Unicast
Broadcast
Multicast
Unicast Transmissions
Description
Limitations
One copy of each frame
or packet is sent to each
destination point
Difficult to scale up
multimedia applications
for increased numbers of
users
If many users, traffic
volume is high and
requires high bandwidth
Unicast Transmissions
Broadcast Transmissions
Description
Limitations
One copy of each frame
or packet is sent to all
points on a network,
regardless of whether or
not a node has requested
it
If not filtered by
internetworking devices,
multimedia broadcast
traffic can produce even
more load on a network
than unicasts, because it
potentially goes to more
destinations
Broadcast Transmissions
Multicast Transmissions
Description
Limitations
Server divides users who
request certain
applications into groups
Each data stream of
frames or packets is a
one-time transmission
that goes to multiple
addresses
More difficult to develop
applications to use
multicasting, but the
payoff in improved
network control and
traffic patterns is well
worth the effort
Multicast Transmissions
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)
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
MOSPF
Works like OSPF in finding the shortest
path from source to destination for multicast
transmissions
PIM
Compatible with networks that use OSPF or
RIP as their main routing protocol
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
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
RSVP
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
Redesigning a Legacy
Network
Add switches and
routers
Redesigning a Legacy
Network
Redesigning a Legacy
Network
Combining Fast Ethernet and
Gigabit Ethernet
WAN Designs to
Accommodate Multimedia
Match WAN to speed and application
requirements of the connected LANs
Reducing WAN Costs and
Increasing Performance
Schedule WAN usage around application
use
Deploy multiple video servers at different
sites throughout the LAN/WAN
Deploying Multiple Video Servers
Vendor Features That
Increase WAN Performance
Snapshot routing
IPX/SPX spoofing
Bandwidth on demand
Multimedia Issues
for the Future
Network-based computer instruction
Video conferencing
Streaming applications
Chapter Summary
Analog and digital video technologies
Audio file technologies
Audio and video sampling
Integrating voice, video, and data on a
network
Voice over IP (VoIP)
How to assess bandwidth and throughput on
a network
continued…
Chapter Summary
Packet and frame transmission techniques
for integrated multimedia applications
How to design LANs and WANs to handle
multimedia traffic
Issues that will affect how multimedia is
transported in the future