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Multimedia Communications

Training goals

Gain a solid understanding of the issues to face when dealing with multimedia services over the wired and wireless Internet, with emphasis on voice and video over IP.

Prerequisites

Good competences in the networking field, but more than anything else, a strong willingness and curiosity to investigate the topics this course covers.

Course programme

This course will be entirely taught in English.

Voice over IP - Architecture. Audio codecs. Network impairments: packet loss, jitter and echo.

Media transport and signaling. Voice quality: objective and subjective evaluations.

RTP and RTCP: protocols for real-time multimedia applications.

Video over IP - Video codecs: spatial-temporal model, video formats. Transmitting video over the network: precompressed video and live video. Potential issues and solutions. A case-study: video streaming over the Internet: the conventional, client-server approach, IP multicast, content delivery networks and peer-to-peer.

Robustness - Error concealment techniques.

Congestion control over the Internet - Implications on multimedia sessions. Rate-based and window-based congestion controls.

Bandwidth estimation - techniques to estimate capacity and available bandwidth (end-to-end and hop-by-hop). Variable packet size approach, packet pair and packet train.

Wireless Multimedia - Wi-Fi and multimediality: the IEEE 802.11e addendum. UMTS services: supporting variable bit rate applications. Service classes. Achievable performance: from GPRS to 3G.

Lab. practise (within the 6 CFU): capture and analysis of video traces over the Internet. Capturing Skype traffic. Evaluating peak-signal-to-noise-ratio (PSNR) for H.264 video after traversing a portion of the public Internet.

Reference bibliography

Slides by the instructor

J. Kurose, K. Ross, "Computer Networks: A Top-Down Approach", ed. Pearson

C. Perkins "RTP Audio and video for the Internet" ed. Addison Wesley