Chapter 10: H.261 and H.263

Overview

There are several standards for video conferencing, as shown in Table 10.1. Figures 10.1 through 10.3 illustrate the block diagrams of several common video conferencing systems.

Table 10.1: Video Conferencing Family of Standards.
	H.310	H.320	H.321	H.322	H.323	H.324	H.324/C
network	Broadband ISDN ATM LAN	Narrowband Switched Digital ISDN	Broadband ISDN ATM LAN	Guaranteed Bandwidth Packet Switched Networks	Non-guaranteed Bandwidth Packet Switched Networks (Ethernet)	PSTN or POTS	Mobile
video codec	MPEG-2 H.261	H.261 H.263	H.261 H.263	H.261 H.263	H.261 H.263	H.261 H.263	H.261 H.263
audio codec	MPEG-2 G.711 G.722 G.728	G.711 G.722 G.728	G.711 G.722 G.728	G.711 G.722 G.728	G.711 G.722 G.723 G.728 G.729	G.723	G.723
multiplexing	H.222.0 H.222.1	H.221	H.221	H.221	H.225.0	H.223	H.223A
control	H.245	H.230 H.242	H.242	H.230 H.242	H.245	H.245	H.245
multipoint		H.231	H.231	H.231	H.323
data	T.120	T.120	T.120	T.120	T.120	T.120	T.120
communications interface	AAL I.363 AJM I.361 PHY I.432	I.400	AAL I.363 AJM I.361 PHY I.400	I.400 and TCP/IP	TCP/IP	V.34 modem	Mobile Radio

Figure 10.1: Typical H.320 System.

Figure 10.2: Typical H.323 System.

Figure 10.3: Typical H.324 System.

H.261

ITU-T H.261 was the first video compression and decompression standard developed for video conferencing. Originally designed for bit rates of p 64 kbps, where p is in the range 1 30, H.261 is now the minimum requirement of all video conferencing standards, as shown in Table 10.1.

A typical H.261 encoder block diagram is shown in Figure 10.4. The video encoder provides a self-contained digital video bitstream which...

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Video Demystified: A Handbook for the Digital Engineer, Fourth Edition

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Chapter 10: H.261 and H.263

Overview

H.261

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