ECE242Spring2011Presentation1-2

ECE242Spring2011Presentation1-2 - ECE 242 Signal...

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March 29, 2011 ECE 242 Signal Compression Introduction to Speech, Audio, Still Image, and Video Compression Jerry D. Gibson 1
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March 29, 2011 Typical Digital Communication System Source Physical Channel Demodulator Modulator Channel Decoder Channel Encoder Source Encoder Source Decoder User )} ( { n x )} ( { n y 2
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March 29, 2011 What is Compression? • Represent a source in digital form with as few bits as possible while still providing an acceptable reproduction of the original 3
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March 29, 2011 Synonyms for Data Compression • Signal Compression • Signal Coding • Source Coding • Source Coding with a Fidelity Criterion • Lossy (Noisy) Source Coding • Lossless (Noiseless) Source Coding • Data Compaction 4
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March 29, 2011 More Synonyms • Redundancy Removal • Bandwidth Compression 5
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March 29, 2011 Components of a Compression Problem • Source • Rate • Distortion Measure • And Complexity 6
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March 29, 2011 Rate, Bits, and Bandwidth • Required network bandwidth set by transmitted bit rate • Bit Rate in bits/sec = bits/sample x samples/ sec • Sampling rate determined by source bandwidth 7
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March 29, 2011 Major Steps in Data Compression 8
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March 29, 2011 Speech and Audio Coding Bandwidths Ø Narrowband Speech — 200 to 3400 Hz Ø Wideband Speech — 50 to 7000 Hz Ø Wideband Audio — 20 to 20,000 Hz – Number of channels – Stereo – Five channel surround 9
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March 29, 2011 10
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Networks and Network Services POTS 28.8-56 Kbits/s ISDN 64-128 Kbits/s ADSL 1.544-8.448 Mbits/s (downstream) 16-640 Kbits/s (upstream) VDSL 12.96-55.2 Mbits/s CATV 20-40 Mbits/s OC-N/STS-N N x 51.84 Mbits/s Ethernet 10 Mbits/s Fast Ethernet 100 Mbits/s Gigabit Ethernet 1,000 Mbits/s FDDI 100 Mbits/s 802.11(wireless) 1, 2, 5.5, 11, and 22 Mbits/s in 2.4 GHz band 802.11 a(wireless) 6-54 Mbits/s in 5GHz band 11
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ECE242Spring2011Presentation1-2 - ECE 242 Signal...

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