Chapter 5 standards for multimedia communications 5.1 Introduction 5.2 reference models 5.3 standards relating to interpersonal communications 5.4 Standards relating to interactive applications over the internet 5.5 standards for entertainment applications

5.1 introduction In this chapter we present an overview of the standards that have been defined for use with multimedia communication A reference model is used for defined the various standards

5.2 reference models The standards associated with the three types of application,show in figure5.1 The functionality of each set of standards is as follows: Application standards Network interface standards Internal network standards

Figure5.1(a)

Figure 5.1(b)(c)

5.2 reference models-5.2.1 Tcp/ip reference model (figure 5.2) Physical layer Link layer Network layer Transport layer Application layer

Figure 5.2

5.2 reference models-5.2.2 Protocol basics The protocol to be used at each layer is chosen to meet the needs of a particular application/network combination Protocol control information(PCI) Protocol data unit(PDU) Show figure 5.3

Figure 5.3(a)

Figure 5.3(b)

5. 3 standards relating to interpersonal communications-5. 3 5.3 standards relating to interpersonal communications-5.3.1 circuit-mode networks Circuit-mode network is show in figure 5.4 Network interface standard Transport layer Multiplexer / demultiplexer System control application Audio and video codecs Multipoint communications service(MCS)

Figure 5.4

Table 5.1

5. 3 standards relating to interpersonal communications-5. 3 5.3 standards relating to interpersonal communications-5.3.1 circuit-mode networks-cont H.320 The H.320 standard is intended for use in end systems that support a range of multimedia application over an ISDN Audio:G.711,G.722,G.728 Video:H.261 User data:T.120 System control/call setup:Q.391 Multiplexing:H.221

5. 3 standards relating to interpersonal communications-5. 3 5.3 standards relating to interpersonal communications-5.3.1 circuit-mode networks-cont H.324 Over bit rate switched networks such as a PSTN Video:H.261,H.263 Audio:G.723.1,G.729 User data:T.120 Multiplexing Total channel bandwidth is divided into a number of separate logical channels Bit-oriented protocol ,the principles of which are shown in figure 5.5

Figure 5.5

5. 3 standards relating to interpersonal communications-5. 3 5.3 standards relating to interpersonal communications-5.3.1 circuit-mode networks-cont Adaptation In order to allow for the possibility of transmission errors being present in the received byte stream associated with each logical channel The adaptation layer supports three difference schemes-AL1,2 and 3 Multipoint conferencing:H.324 System control :h.245 is concerned with the overall control of the end system

5. 3 standards relating to interpersonal communications-5. 3 5.3 standards relating to interpersonal communications-5.3.1 circuit-mode networks-cont H.321/H.310 Intended for use with terminals that provide a range of multimedia application over a B-ISDN H.322 Intended for use with end systems that support interpersonal communication applications over a local area network(LAN)

5. 3 standards relating to interpersonal communications-5. 3 5.3 standards relating to interpersonal communications-5.3.2 packet-switched networks H.323 Attached either to the same LAN or to different LANs H.323 is intended for use with LANs that provide a non-guaranteed QoS Figure 5.6 show structure

Figure 5.6

5. 3 standards relating to interpersonal communications-5. 3 5.3 standards relating to interpersonal communications-5.3.2 packet-switched networks-cont Audio and video coding Audio codec:either G.711 or G.728 Video codec:either H.261 or H.263 Call setup:H.323 gatekeeper can be used Figure 5.7 two-party call setup procedure using an h.323 gatekeeper Figure 5.8 H.323 multiplexing/ demultiplexing

Figure 5.7

Figure 5.8

5. 3 standards relating to interpersonal communications-5. 3 5.3 standards relating to interpersonal communications-5.3.2 packet-switched networks-cont Interworking End system that are attached to a circuit-mode network is achieved. This is through H.323 gateway Figure 5.9

Figure 5.9

5. 3 standards relating to interpersonal communications-5. 3 5.3 standards relating to interpersonal communications-5.3.2 packet-switched networks-cont IETF Early IETF provided a basic two-party telephony service between two IP hosts Later IETF provided a more versatile facility supporting both multiparty conferencing and broadcast services Signaling protocol Session initiation protocol (SIP) Sip provides services for user location,call establishment,and call participation management

5. 3 standards relating to interpersonal communications-5. 3 5.3 standards relating to interpersonal communications-5.3.2 packet-switched networks-cont Session description protocol(SDP) When a user is invited to join in a call/session

5. 3 standards relating to interpersonal communications-5. 3 5.3 standards relating to interpersonal communications-5.3.3 electronic mail Internet mail Figure 5.10 email over the internet User agent(UA) Message transfer agent(MTA) Message store(MS) Simple mail transfer protocol(SMTP) Domain name server(DNS)

Figure 5.10

5. 3 standards relating to interpersonal communications-5. 3 5.3 standards relating to interpersonal communications-5.3.3 electronic mail-cont MIME(multipurpose internet mail extensions) RFC 822:email messages are written in English and are made up of just ASCII characters Extensions to the basic format defined in RFC 822 were added.these are defined in RFC 2045 and are known as MIME

5. 3 standards relating to interpersonal communications-5. 3 5.3 standards relating to interpersonal communications-5.3.3 electronic mail-cont e-mail gateways Show figure 5.11 Two problem: Format of the mail message is often different The application protocol are also different To overcome these problems,a device known as an email gateway is used,show figure 5.12

Figure 5.11

Figure 5.12

5.4 standards relating to interactive applications over the internet-5.4.1 information browsing Figure 5.13 show information browsing

figure 5.14

5.4 standards relating to interactive applications over the internet-5.4.2 electronic commerce To send detail of your credit card in order to purchase Figure 5.15 electronic commerce Common gateway interface(CGI) security

Figure 5.15

5.4 standards relating to interactive applications over the internet-5.4.3 intermediate systems Communication between the client and server is achieved through a networking device Show figure 5.16 Security gateway Packet filtering Proxy server

Figure 5.16

5.4 standards relating to interactive applications over the internet-5.4.4 Java and JavaScript Figure 5.17 Applet Virtual machine Bytecode Javascript Embed java code into an HTML page directly

Figure5.17

5. 5 standards for entertainment applications –5. 5 5.5 standards for entertainment applications –5.5.1 Movie/video-on-demand Transmission format (figure 5.18) Elementary streams Packetized ES (PES) System time clock(STC) Pack System clock reference(SRC)

Figure 5.18

5. 5 standards for entertainment applications –5. 5 5.5 standards for entertainment applications –5.5.1 Movie/video-on-demand-cont Distribution network Figure5.19(a) show telephony company architecture Figure5.19(b) show cable TV company architecture

Figure 5.19

5. 5 standards for entertainment applications –5. 5 5.5 standards for entertainment applications –5.5.2 Interactive television Base on MPEG-2 format TV program multiplexing(a)PS and TS generation (b) TS format (figure 5.20) System-level Program allocation table(PAT) Program map table(PMT) Conditional access table(CAT)

Figure 5.20