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Transform-domain Wyner-Ziv Codec for Video

Transform-domain Wyner-Ziv Codec for Video. 教師 : 楊士萱 老師 學生 : 李桐照 同學. OutLine. 1:Review of DSC 2:Wyner-Ziv Codec for Video 3:Turbo Coding 4:Future Work. Review of DSC. Distributed Source Coding. Compression of two or more correlated source

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Transform-domain Wyner-Ziv Codec for Video

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  1. Transform-domain Wyner-Ziv Codec for Video 教師 : 楊士萱 老師 學生 : 李桐照 同學

  2. OutLine 1:Review of DSC2:Wyner-Ziv Codec for Video3:Turbo Coding4:FutureWork

  3. Review of DSC Distributed Source Coding • Compression of two or more correlated source • The source do not communicate with each other • (hence distributed coding) • Decoding is done jointly • (say at the base station)

  4. Wyner-Ziv Codec for Video

  5. Wyner-Ziv Codec for Video K: coefficient number Xk: coefficient bands ex: X1=A1A2A3A4

  6. Wyner-Ziv Codec for Video 假設DCT值域:0~255 Ex: (DC值對應64) 0,3,…..255 64區間因此用6 bits即可表示DC值 EX: q1=Q(A1),Q(A2),Q(A3),Q(A4)

  7. Wyner-Ziv Codec for Video EX: q1=Q(A1),Q(A2),Q(A3),Q(A4) Q(A1)=111100 Q(A2)=110111 Q(A3)=110011 Q(A4)=111011

  8. Wyner-Ziv Codec for Video Turbo Coding 採用 Systematic code type Turbo Encoder -@ Message bits :1111 -@ Parity bits: Buffer store:-@ Message bits -@ Parity bits

  9. Wyner-Ziv Codec for Video Buffer store:-@ Message bits -@ Parity bits Normal:-@(Yk) Message bits -@ Parity bits Error Probability >10^-3 Request bits :-@ Message bits

  10. Wyner-Ziv Codec for Video

  11. Turbo Coding - Encoding

  12. Turbo Coding - Encoding Interleaver type: 1:Block Interleaver 2:Random Interleaver* 3:S-Random Interleaver* 4:Prime Interleaver* 5:Convolutional Interleaver*

  13. Turbo Coding - Encoding Message bits: 1234567890 Interleaver Read out Write in Read out bits:1357924680 DeInterleaver Write in Read out

  14. Turbo Coding - Encoding

  15. Turbo Coding - Encoding 若不經過Puncture時,則 Rate=1/3 若經過Puncture,則我們可以調整傳輸資料使 Rate=1/2 提升傳輸效率

  16. Turbo Coding - Encoding 1110011000 0101001001 0100011101 0110111101

  17. Turbo Coding - Decoding

  18. Turbo Coding - Decoding A Posteriori Probability (APP): Assume Tr=+1 or -1 P(Tr=i|x)=P(x|Tr=i)*P(Tr=i)/P(x) Log-Likelihood Ratio (LLR): L(Tr|x)=log[ P(Tr=+1|x)/P(Tr=-1|x)] =log[P(x|Tr=+1)*P(Tr=+1)/ P(x|Tr=-1)*P(Tr=-1)] = log[P(x|Tr=+1)/ P(x|Tr=-1)]+log[P(Tr=+1)/P(Tr=-1)] =L(x/Tr)+L(Tr)

  19. Message Passing Concept Turbo Coding - Decoding :Extrinsic Information Check Nodes: A,…F

  20. Turbo Coding - Decoding 所有英文字母的數目 =(左相鄰字母告知的數目+右相鄰字母告知的數目)+自己 Overall Information = Extrinsic Information + Intrinsic Information

  21. Turbo Coding - Decoding P channel :L(x/Tr) P a prioir :L(Tr) P extrinsic :as other SISO Decoder’s Pa prioir P a posteriori : Decision Message bits

  22. Turbo Coding - Decoding SISO decoder 1:MAP Rule 2:Log-MAP 3:Soft Output Viterbi Algorithm*

  23. Turbo Coding - Error Detection 傳統 Turbo Coding-Error Detection 方法1: CRC 對於Message長度太短,會浪費過多bits 在CRC上 方法2: 奇(偶)同位元 對於Message長度太短,比較不會浪費bits在其上

  24. Future Work 1:了解 Turbo Decoder 原理 2:寫出一個簡易型可以配合DSC系統的 Turbo Coding 3:將Turbo Coder換成LDPC

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