1. CChhaapptteerr 2255
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Objectives
Upon completion you will be able to:
• Know the characteristics of the 3 types of services
• Understand the methods of digitizing and compressing.
• Understand jitter, translation, and mixing in real-time traffic
• Understand the role of RTP and RTCP in real-time traffic
• Understand how the Internet can be used as a telephone network
TCP/IP Protocol Suite 1
6. 25.1 DIGITIZING AUDIO AND VIDEO
Before audio or video signals can be sent on the Internet, tthheeyy nneeeedd ttoo bbee
ddiiggiittiizzeedd.. WWee ddiissccuussss aauuddiioo aanndd vviiddeeoo sseeppaarraatteellyy..
TThhee ttooppiiccss ddiissccuusssseedd iinn tthhiiss sseeccttiioonn iinncclluuddee::
DDiiggiittiizziinngg AAuuddiioo
DDiiggiittiizziinngg VViiddeeoo
TCP/IP Protocol Suite 6
8. 25.2 AUDIO AND VIDEO
COMPRESSION
To send audio or video over the Internet rreeqquuiirreess ccoommpprreessssiioonn..
TThhee ttooppiiccss ddiissccuusssseedd iinn tthhiiss sseeccttiioonn iinncclluuddee::
AAuuddiioo CCoommpprreessssiioonn
VViiddeeoo CCoommpprreessssiioonn
TCP/IP Protocol Suite 8
33. NNoottee::
Translation means changing the
encoding of a payload to a lower
quality to match the bandwidth
of the receiving network.
TCP/IP Protocol Suite 33
34. NNoottee::
Mixing means combining several
streams of traffic into one stream.
TCP/IP Protocol Suite 34
35. NNoottee::
TCP, with all its sophistication, is not
suitable for interactive multimedia
traffic because we cannot allow
retransmission of packets.
TCP/IP Protocol Suite 35
36. NNoottee::
UDP is more suitable than TCP for
interactive traffic. However, we need
the services of RTP, another transport
layer protocol, to make up for the
deficiencies of UDP.
TCP/IP Protocol Suite 36
37. 25.6 RTP
Real-time Transport Protocol (RTP) is the protocol ddeessiiggnneedd ttoo hhaannddllee
rreeaall--ttiimmee ttrraaffffiicc oonn tthhee IInntteerrnneett.. RRTTPP ddooeess nnoott hhaavvee aa ddeelliivveerryy
mmeecchhaanniissmm;; iitt mmuusstt bbee uusseedd wwiitthh UUDDPP..
TThhee ttooppiiccss ddiissccuusssseedd iinn tthhiiss sseeccttiioonn iinncclluuddee::
RRTTPP PPaacckkeett FFoorrmmaatt
UUDDPP PPoorrtt
TCP/IP Protocol Suite 37