Chapter 9 Computer Networking Multimedia A TOP-DOWN APPROACH SEVENTH EDITION Networking KUROSE·ROSS A note on the use of these Powerpoint slides: We're making these slides freely available to all (faculty,students,readers). They're in PowerPoint form so you see the animations;and can add,modify. and delete slides (including this one)and slide content to suit your needs. They obviously represent a lot of work on our part.In return for use,we only ask the following: Computer If you use these slides(e.g.,in a class)that you mention their source Networking:A Top (after all,we'd like people to use our book!) If you post any slides on a ww site,that you note that they are adapted from(or perhaps identical to)our slides,and note our copyright of this Down Approach material. 7th edition Thanks and enjoy!JFK/KWR Jim Kurose,Keith Ross Al material copyright19-2016 Pearson/Addison Wesley J.F Kurose and K.W.Ross,All Rights Reserved April 2016 Multimedia Networking 9-1
Computer Networking: A Top Down Approach A note on the use of these Powerpoint slides: We’re making these slides freely available to all (faculty, students, readers). They’re in PowerPoint form so you see the animations; and can add, modify, and delete slides (including this one) and slide content to suit your needs. They obviously represent a lot of work on our part. In return for use, we only ask the following: ▪ If you use these slides (e.g., in a class) that you mention their source (after all, we’d like people to use our book!) ▪ If you post any slides on a www site, that you note that they are adapted from (or perhaps identical to) our slides, and note our copyright of this material. Thanks and enjoy! JFK/KWR All material copyright 1996-2016 J.F Kurose and K.W. Ross, All Rights Reserved 7 th edition Jim Kurose, Keith Ross Pearson/Addison Wesley April 2016 Chapter 9 Multimedia Networking Multimedia Networking 9-1
Multimedia networking:outline 9.I multimedia networking applications 9.2 streaming stored video 9.3 voice-over-IP 9.4 protocols for real-time conversational applications 9.5 network support for multimedia Multimedia Networking 9-2
Multimedia networking: outline 9.1 multimedia networking applications 9.2 streaming stored video 9.3 voice-over-IP 9.4 protocols for real-time conversational applications 9.5 network support for multimedia Multimedia Networking 9-2
Multimedia:audio analog audio signal sampled at constant rate quantization ·telephone:8,000 quantized error value of samples/sec analog value ·CD music:44,I00 analog samples/sec signal each sample quantized,i.e., rounded ·eg,28=256 possible time quantized values sampling rate 。each quantized value (N sample/sec) represented by bits, e.g.,8 bits for 256 values Multimedia Networking 9-3
Multimedia: audio ▪ analog audio signal sampled at constant rate • telephone: 8,000 samples/sec • CD music: 44,100 samples/sec ▪ each sample quantized, i.e., rounded • e.g., 28=256 possible quantized values • each quantized value represented by bits, e.g., 8 bits for 256 values time audio signal amplitude analog signal quantized value of analog value quantization error sampling rate (N sample/sec) Multimedia Networking 9-3
Multimedia:audio example:8,000 samples/sec, 256 quantized values:64,000 bps quantization quantized error value of receiver converts bits back to analog value analog signal: analog some quality reduction signal example rates ■CD:I.4 II Mbps time ■MP3:96,I28,160kbps sampling rate (N sample/sec) Internet telephony:5.3 kbps and up Multimedia Networking 9-4
Multimedia: audio ▪ example: 8,000 samples/sec, 256 quantized values: 64,000 bps ▪ receiver converts bits back to analog signal: • some quality reduction example rates ▪ CD: 1.411 Mbps ▪ MP3: 96, 128, 160 kbps ▪ Internet telephony: 5.3 kbps and up time audio signal amplitude analog signal quantized value of analog value quantization error sampling rate (N sample/sec) Multimedia Networking 9-4
spatial coding example:instead Multimedia:video of sending N values of same color(all purple),send only two values:color value (purple)and numberof repeated values(N) video:sequence of images displayed at constant rate ·e.g,24 images/sec digital image:array of pixels each pixel represented by bits coding:use redundancy within and between images frame i to decrease bits used to encode image spatial (within image) temporal coding example. instead of sending ·temporal(from one complete frame at i+1, image to next) send only differences from frame i frame i+1 Multimedia Networking 9-5
▪ video: sequence of images displayed at constant rate • e.g., 24 images/sec ▪ digital image: array of pixels • each pixel represented by bits ▪ coding: use redundancy within and between images to decrease # bits used to encode image • spatial (within image) • temporal (from one image to next) Multimedia: video ……………………...… spatial coding example: instead of sending N values of same color (all purple), send only two values: color value (purple) and number of repeated values (N) ……………………...… frame i frame i+1 temporal coding example: instead of sending complete frame at i+1, send only differences from frame i Multimedia Networking 9-5