1. Chapter 28. Network Management Chapter 29. Multimedia
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2. Network Management System and SNMP Concepts
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3. Internet Audio/Video
Streaming stored audio/video refers to on-demand requests for compressed audio/video files
Streaming live audio/video refers to the broadcasting of radio and TV programs through the Internet
Interactive audio/video refers to the use of the Internet for interactive audio/video applications
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4. Digitizing Audio and Video
Voice: 64 Kbps = 8,000 samples x 8 bits
Music: 44,100 samples x 16 bits ->
705.6 Kbps for mono, 1,411 Mbps for stereo
Digitizing video
25 frames/second, 1024 x 768 pixels, 24 bits/pixel
2 x 25 x 1024 x 768 x 24 = 944 Mbps
Compression is needed to send video (audio) over the Internet
Audio Compression
Predictive encoding: GSM(13Kbps), G.729(8Kbps),
G.723.3(6.4 or 5.3 Kbps)
Perceptual encoding: MP3 (MPEG audio layer 3)
Video Compression
Image compression: JPEG
Video compression: MPEG
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5. Streaming Stored AV: (1)
First approach: Using a Web server
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6. Streaming Stored AV: (2)
Second approach: Using a Web server with metafile
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7. Streaming Stored AV: (3)
Third approach: Using a media server
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8. Streaming Stored AV: (4)
Fourth approach: Using a media server and RTSP
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9. Real-time Interactive AV
Time relationship
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10. Real-time Interactive AV
Jitter is introduced in real-time data by the delay between packets
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11. Timestamp
To prevent jitter, we can timestamp the packets and separate the arrival time from the playback time
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12. Playback Buffer A playback buffer is required for real-time traffic
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13. Characteristics of Real-time AV Communication
A sequence number on each packet is required for real-time traffic
Real-time traffic needs the support of multicasting
Translation means changing the encoding of a payload to a lower quality to match the bandwidth of the receiving network
Mixing means combining several streams of traffic into one stream.
Support from transport layer protocol
TCP, with all its sophistication, is not suitable for interactive multimedia traffic because we cannot allow retransmission of packets.
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
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14. Real-time Transport Protocol (RTP)
RTP is designed to handle real-time traffic on the Internet
RTP uses a temporary even-numbered UDP port
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15. Real-time Transport Control Protocol (RTCP)
RTCP is designed to control the flow and quality of data and allow the recipient to send feedback to the source or sources
RTCP uses an odd-numbered UDP port number that follows the port number selected for RTP
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16. Voice over IP
Session Initiation Protocol (SIP) by IETF and H.323 by ITU-T
SIP
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17. SIP Simple Session
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18. Tracking the Callee
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19. H.323 Architecture and Protocols
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20. H.323 Example
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