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Streaming stored audio/video refers to

on-demand requests for compressed

audio/video files.

NoteNote::

Streaming live audio/video refers to

the broadcasting of radio and TV

programs through the Internet.

NoteNote::

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Interactive audio/video refers to the

use of the Internet for interactive

audio/video applications.

NoteNote::

28.1 Digitizing Audio and Video28.1 Digitizing Audio and Video

Digitizing Audio

Digitizing Video

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Compression is needed to send video

over the Internet.

NoteNote::

28.2 Audio/Video Compression28.2 Audio/Video Compression

Audio Compression

Video Compression

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Figure 28.4 Case 1: uniform gray scale

Figure 28.5 Case 2: two sections

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Figure 28.6 Case 3: gradient gray scale

Figure 28.7 Reading the table

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28.3 Streaming Stored Audio/Video28.3 Streaming Stored Audio/Video

First Approach

Second Approach

Third Approach

Fourth Approach

Figure 28.10 Using a Web server

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Figure 28.11 Using a Web server with a metafile

Figure 28.12 Using a media server

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Figure 28.13 Using a media server and RTSP

28.4 Streaming Live Audio/Video28.4 Streaming Live Audio/Video

Broadcasting of liveBroadcasting of live

audio/video overaudio/video over

the Internetthe Internet

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28.5 Interactive Audio/Video28.5 Interactive Audio/Video

Characteristics

RTP

RTCP

Figure 28.14 Time relationship

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Jitter is introduced in real-time data

by the delay between packets.

NoteNote::

Figure 28.15 Jitter

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Figure 28.16 Timestamp

To prevent jitter, we can timestamp the

packets and separate the arrival time

from the playback time.

NoteNote::

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Figure 28.17 Playback buffer

A playback buffer is required for real-

time traffic.

NoteNote::

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A sequence number on each packet is

required for real-time traffic.

NoteNote::

Real-time traffic needs the support of

multicasting.

NoteNote::

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Translation means changing the

encoding of a payload to a lower

quality to match the bandwidth of the

receiving network.

NoteNote::

Mixing means combining several

streams of traffic into one stream.

NoteNote::

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TCP, with all its sophistication, is not

suitable for interactive multimedia

traffic because we cannot allow

retransmission of packets.

NoteNote::

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.

NoteNote::

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Figure 28.18 RTP

RTP uses a temporary even-numbered

UDP port.

NoteNote::

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Figure 28.19 RTCP message types

RTCP uses an odd-numbered UDP

port number that follows the port

number selected for RTP.

NoteNote::

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Figure 28.20 SIP messages

Figure 28.21 SIP formats

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Figure 28.22 SIP simple session

Figure 28.23 Tracking the callee

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Figure 28.24 H.323 architecture

Figure 28.25 H.323 protocols

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Figure 28.26 H.323 example