Multimedia Over Todays Internet TCP/UDP/IP: " best-effort service" o no guarantees on delay, loss ? But you said multimedia apps requires Qos and level of performance to be effective oday's Internet multimedia applications use application-level techniques to mitigate (as best possible) effects of delay, loss
Multimedia Over Today’s Internet TCP/UDP/IP: “best-effort service” no guarantees on delay, loss Today’s Internet multimedia applications use application-level techniques to mitigate (as best possible) effects of delay, loss But you said multimedia apps requires QoS and level of performance to be effective! ? ? ? ? ? ? ? ? ? ? ?
How should the Internet evolve to better support multimedia Integrated services philosophy: Differentiated services o Fundamental changes in philosophy: Internet so that apps can o Fewer changes to internet reserve end-to-end infrastructure, yet provide bandwidth 1st and 2nd class service 口 Requires new, complex software in hosts routers Laissez-faire 口nomaⅰ or changes o more bandwidth when needed o content distribution application-layer multicast o application layer What's your opinion?
How should the Internet evolve to better support multimedia? Integrated services philosophy: Fundamental changes in Internet so that apps can reserve end-to-end bandwidth Requires new, complex software in hosts & routers Laissez-faire no major changes more bandwidth when needed content distribution, application-layer multicast application layer Differentiated services philosophy: Fewer changes to Internet infrastructure, yet provide 1st and 2nd class service. What’s your opinion?
A few words about audio compression D Analog signal sampled O Example: 8,000 at constant rate samples/sec, 256 o telephone: 8.000 quantized values-> samples/sec 64000bps o CD music: 44100 o Receiver converts it samples/sec back to analog signal: o Each sample quantized o some quality reduction ie rounded o eg, 28=256 possible Example rates quantized values O CD: 1.411 Mbps o Each quantized value O MP3: 96, 128, 160 kbps represented by bits o Internet telephony o8 bits for 256 values 5.3-13 kbps
A few words about audio compression Analog signal sampled at constant rate telephone: 8,000 samples/sec CD music: 44,100 samples/sec Each sample quantized, ie, rounded eg, 28=256 possible quantized values Each quantized value represented by bits 8 bits for 256 values Example: 8,000 samples/sec, 256 quantized values --> 64,000 bps Receiver converts it back to analog signal: some quality reduction Example rates CD: 1.411 Mbps MP3: 96, 128, 160 kbps Internet telephony: 5.3 - 13 kbps
A few words about video compression o Video is sequence of Examples: images displayed at O MPEG 1(CD-ROM)1.5 constant rate Mbps o e.g. 24 images/sec O MPEG2(DVD)3-6 Mbps Digital image is array of O MPEG4 often used in pixels Internet, 1 Mbps) o Each pixel represented Research by bits O Layered(scalable)video o Redundancy o adapt layers to available o spacial bandwidth o temporal
A few words about video compression Video is sequence of images displayed at constant rate e.g. 24 images/sec Digital image is array of pixels Each pixel represented by bits Redundancy spacial temporal Examples: MPEG 1 (CD-ROM) 1.5 Mbps MPEG2 (DVD) 3-6 Mbps MPEG4 (often used in Internet, < 1 Mbps) Research: Layered (scalable) video adapt layers to available bandwidth
Chapter 6 outline 0 6. 1 Multimedia 0 6.5 beyond Best effort Networking Applications o 6.6 Scheduling and 口6.25 reaming stored Policing Mechanisms audio and video 0 6.7 Integrated Services O RTSP 06. 8 RSVP 06.3 Real-time g6.9 Differentiated Multimedia: Internet Services Phone case study 口64 Protocols for real- Time Interactive Applications O RTPRTCP SIP
Chapter 6 outline 6.1 Multimedia Networking Applications 6.2 Streaming stored audio and video RTSP 6.3 Real-time Multimedia: Internet Phone Case Study 6.4 Protocols for RealTime Interactive Applications RTP,RTCP SIP 6.5 Beyond Best Effort 6.6 Scheduling and Policing Mechanisms 6.7 Integrated Services 6.8 RSVP 6.9 Differentiated Services