1 o characteristics – From an application-level API to the physical layer – CBR, VBR, ABR and UBR – Cell: bytes – Virtual circuits: virtual channel identifier (VCI) – No retransmission on a link-by-link basis – Congestion control only within the ATM ABR – Run over any physical layer ATM

2 o Fig 5.44 and 5.45

3 o Fig 5.47

4 o IP over ATM – Dynamic vs Permanent virtual channel – pp – Fig 5.52

Ch 6. Multimedia Networking Myungchul Kim

6 o Networked multimedia applications: timing and tolerance of data loss o Delay-sensitive and loss-tolerant o Streaming stored audio and video – Stored media – Streaming: avoids having to download the entire file before beginning playout, Realplayer, QuickTime and Media Player – Continuous playout o Streaming live audio and video – Not stored, not fast-forward – Use the IP multicast

7 o Real-time interactive audio and video – Real-time – Interactive – Internet phone – For voice, 150 msec, msec, 400 msec o Hurdles for multimedia – End-to-end delay for a packet – Variation of packet delay – Packet loss o Supporting multimedia better in Internet – Reservation approach – Laissez-faire approach: ISP, CDN, multicast overlay networks – Differentiation approach

8 o Audio and video compression – 1024 pixels * 1024 pixels with each pixel encoded into 24 bits => 3 Mbyte – 7 Min over a 64 kbps link – If the image is compressed at 10:1, o Audio compression – 8000 samples per second -> quantization with 256 values (8bits)-> 64,000 bits/second – Pulse code modulation – GSM, G.729, MPEG 1 layer 3(MP3),… o Video compression – MPEG 1, 2, 4, H.261

9 o Real-time streaming protocol (RTSP) – User interactivity – RealPlayer and Media Player – Decompression, jitter removal, and correction – Fig 6.2 Streaming stored audio and video

10 o Fig 6.3

11 o RTSP – Control the playback of continuous media – No related with compression schemes, encapsulation in packets, transportation, buffering – Out-of-band protocol – Over either TCP or UDP – Pause/resume, playback, fast-forward, and rewind

12 o Fig 6.5

13 o Every 20 msec over UDP o Packet loss, end-to-end delay, and packet jitter o Removing jitter at the receiver for audio – With a sequence number, a timestamp or – delaying playout at the receiver Internet phone

14 o Fig 6.6