Chapter 7 Computer Networking A Top-Down Approach Multimedia Notworking KUROSE ROSS A note on the use of these ppt slides: Computer 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. Networking:A 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 Top Down ask the following: If you use these slides (e.g.,in a class)that you mention their source Approach (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 6th edition from (or perhaps identical to)our slides,and note our copyright of this Jim Kurose,Keith Ross material. Addison-Wesley Thanks and enjoy!JFK/KWR March 2012 urhts Reserved Multmedia Networking 7-1
Chapter 7 Multimedia Networking Computer Networking: A Top Down Approach 6th edition Jim Kurose, Keith Ross Addison-Wesley March 2012 A note on the use of these ppt 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 1996-2012 J.F Kurose and K.W. Ross, All Rights Reserved Multmedia Networking 7-1
Multimedia networking:outline 7.1 multimedia networking applications 7.2 streaming stored video 7.3 voice-over-IP 7.4 protocols for rea/-time conversational applications 7.5 network support for multimedia Multmedia Networking 7-2
Multimedia networking: outline 7.1 multimedia networking applications 7.2 streaming stored video 7.3 voice-over-IP 7.4 protocols for real-time conversational applications 7.5 network support for multimedia Multmedia Networking 7-2
Multimedia networking:outline 7.1 multimedia networking applications 7.2 streaming stored video 7.3 voice-over-IP 7.4 protocols for real-time conversational applications 7.5 network support for multimedia Multmedia Networking 7-3
Multimedia networking: outline 7.1 multimedia networking applications 7.2 streaming stored video 7.3 voice-over-IP 7.4 protocols for real-time conversational applications 7.5 network support for multimedia Multmedia Networking 7-3
Multimedia:audio analog audio signal sampled at constant rate quantization quantized error value of telephone:8,000 analog value samples/sec analog ·CD music:44,100 signal samples/sec apnldwe jeubIs olpne each sample quantized, i.e.,rounded time ·e.g,28=256 possible quantized values sampling rate (N sample/sec) each quantized value represented by bits,e.g.,8 bits for 256 values Multmedia Networking 7-4
Multimedia: audio Multmedia Networking 7-4 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., 2 8=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:audio example:8,000 samples/sec,256 quantized values:64,000 quantization quantized error value of bps analog value receiver converts bits back analog to analog signal: signal some quality reduction o!pne example rates time CD:1.411 Mbps sampling rate ÷MP3:96,128,160kbps (N sample/sec) Internet telephony:5.3 kbps and up Multmedia Networking 7-5
Multimedia: audio Multmedia Networking 7-5 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)
spatial coding example:instead Multimedia:video of sending N values of same color (all purple),send only two values:color value (purple)and number of repeated values(N) video:sequence of images displayed at 889888899838 constant rate ·e.g.24 images/sec digital image:array of pixels ■each pixel represented by bits frame i coding:use redundancy within and between images to decrease temporal coding example. bits used to encode instead of sending complete frame at i+1, image send only differences from spatial (within image) frame i temporal (from one frame i+1 image to next) Multmedia Networking 7-6
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) Multmedia Networking 7-6 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
spatial coding example:instead Multimedia:video of sending N values of same color(all purple),send only two values:color value (purple)and CBR:(constant bit rate): number of repeated values (N) video encoding rate fixed 2080088002800 VBR:(variable bit rate): video encoding rate changes as amount of spatial,temporal coding changes examples: ■MPEG1(CD-ROM) frame i 1.5 Mbps ·MPEG2(DVD)3-6 Mbps temporal coding example. instead of sending ■MPEG4(often used in complete frame at i+1. send only differences from Internet,1 Mbps) frame i frame i+1 Multmedia Networking 7-7
Multmedia Networking 7-7 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 CBR: (constant bit rate): video encoding rate fixed VBR: (variable bit rate): video encoding rate changes as amount of spatial, temporal coding changes examples: MPEG 1 (CD-ROM) 1.5 Mbps MPEG2 (DVD) 3-6 Mbps MPEG4 (often used in Internet, < 1 Mbps)
Multimedia networking:3 application types streaming,stored audio,video streaming:can begin playout before downloading entire file stored (at server):can transmit faster than audio/video will be rendered (implies storing/buffering at client) e.g.,YouTube,Netflix,Hulu conversational voice/video over IP interactive nature of human-to-human conversation limits delay tolerance e.g.,Skype streaming live audio,video e.g.,live sporting event (futbol) Multmedia Networking 7-8
Multimedia networking: 3 application types Multmedia Networking 7-8 streaming, stored audio, video streaming: can begin playout before downloading entire file stored (at server): can transmit faster than audio/video will be rendered (implies storing/buffering at client) e.g., YouTube, Netflix, Hulu conversational voice/video over IP interactive nature of human-to-human conversation limits delay tolerance e.g., Skype streaming live audio, video e.g., live sporting event (futbol)
Multimedia networking:outline 7.1 multimedia networking applications 7.2 streaming stored video 7.3 voice-over-IP 7.4 protocols for real-time conversational applications 7.5 network support for multimedia Multmedia Networking 7-9
Multimedia networking: outline 7.1 multimedia networking applications 7.2 streaming stored video 7.3 voice-over-IP 7.4 protocols for real-time conversational applications 7.5 network support for multimedia Multmedia Networking 7-9
Streaming stored video: ejep anneinwno 2.video sent 1.video 3.video received, recorded network delay played out at client e.g.,30 (fixed in this (30 frames/sec) time frames/so example) streaming:at this time,client playing out early part of video. while server still sending later part of video Multmedia Networking 7-10
Streaming stored video: 1. video recorded (e.g., 30 frames/sec ) 2. video Csent umu al tive da at streaming: at this time, client playing out early part of video, while server still sending later part of video network delay (fixed in this example) time Multmedia Networking 7-10 3. video received, played out at client (30 frames/sec)