Source-Channel Prediction in Error Resilient Video Coding

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Hugo Owen
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1 Source-Chael Predcto Error Reslet Vdeo Codg Hua Yag ad Keeth Rose Sgal Compresso Laboratory ECE Departmet Uversty of Calfora, Sata Barbara

2 Outle Itroducto Source-chael predcto Smulato results Coclusos 7/8/03 ICME

3 Itroducto Exstet error reslet approaches o the predcto mechasm Slce codg lmt predcto wth certa o-overlappg spatal regos Vdeo redudacy codg Multple depedetly predcted threads Mult-frame moto compesato Multple referece frames for predcto Feature commo: assume the same uderlyg covetoal predcto framework Framework: separate source-chael codg Predcto: past ecoder recostructed frames Moto estmato crtero: mmum predcto error 7/8/03 ICME

4 Itroducto Va cosderg packet loss effects durg ecodg, jot source-chael codg usually acheves better error reslece tha that of separate codg. Our proposed approach Predcto s based o expected decoder recostructo of the prevous frames. Novelty Ulke all the other exstet error reslet predcto schemes ad all the other exstet source-chael codg schemes, our proposed method s actually a source-chael predcto scheme. 7/8/03 ICME

5 Itroducto 0 p 1 p 2 p 3 p packet loss rate of vdeo packet. 1-p 1 1-p 2 1-p 3 Ecoder recostructo,.e. best possble decoder recostructo: p 1 p 2 p 3 quatzato loss oly. 1-p 3 1-p 2 p 2 p 3 1-p 3 p 3 1-p 3 Other possble decoder recostructos: dfferet trasmsso loss patters. p 3 Expected decoder recostructo: quatzato loss & trasmsso loss. 7/8/03 ICME

6 Itroducto Expected decoder recostructo Ecoder s estmate of the decoder recostructo. Gve the packet loss rate, t ca be accurately computed wth the ROPE method. Recursve optmal per-pxel estmate (ROPE) Basc dea: ~ 2 ~ ~ d = E{( f f ) } = ( f ) 2 f E{ f } + E{( f ROPE accurately computes these ukow quattes a recursve maer for all the pxels of every frame. Accurate & Low complexty 2 Radom varable Frequetly used to estmate ed-to-ed dstorto varous RD optmzato scearos. Now we use these expectatos for source-chael predcto. ) 2 } ukow 7/8/03 ICME

7 Source-chael Predcto Covetoal predcto Source-chael predcto Predcto resdue f fˆ f res + j = 1 ~ { + f j } = E 1 = f f For pxel frame : f j fˆ 1 res f ~ j f 1 Orgal ad predcted values Ecoder ad decoder recostructo values of pxel j frame -1 to predct pxel frame. Predcto error to be quatzed 7/8/03 ICME

8 Source-chael Predcto Source-chael predcto + E f j 1 s the optmal predcto the sese of mmum MSE ed-to-ed dstorto. Pedg problem: moto estmato crtero? Crtero the covetoal scheme Plug : Crtero I m f MB m ~ { } 2 + ( f f ) = m ( f fˆ ) ~ { f } + j = E 1 MB ~ + ( f ) E{ f 1 } MB Costat value: Not the actual predctor of the decoder 7/8/03 ICME

9 Source-chael Predcto Pedg problem: moto estmato crtero? (cot.) ( ) Crtero II + m { f f 1 MB ~ 2 E } Radom varable: Actual predctor of the decoder Crtero II s superor tha Crtero I that t explctly accouts for the radomess of the decoder s actual predctor. 7/8/03 ICME

10 Source-chael Predcto Aother terpretato of Crtero II m = m MB = m D R = E MB ~ + ( f f ) ~ ~ + ( f E{ f }) + ( E{( f ) } E { f }) [(1 p) D + D ] ( f ) f MB R D D 2 D = MB E 1 ~ ( f f ) 1 Whle Crtero II cosders the properly weghted mpacts of both D R ad D D, cotrast, Crtero I oly cosders D R. I ths sese, Crtero II s more comprehesve. 2 7/8/03 ICME

11 Smulato Results Smulato codtos H.263+ vdeo codec System performace: average lumace PSNR 50 dfferet packet loss patters Testg scearos No INTRA Updatg Perodc INTRA Updatg For packet loss rate p, codg a MB INTRA mode oce for every 1/p frames. R-D optmzed INTRA Updatg For each MB, select ts codg mode as INTER or INTRA wth the R-D crtero. 7/8/03 ICME

12 PSNR(dB) Forema (300kbps) EP SCP_CI SCP_CII Frame No. (a) No INTRA updatg ( p = 10%) Forema (200kbps) Forema (200kbps) EP SCP_CI SCP_CII EP SCP_CI SCP_CII PSNR (db) PSNR (db) Packet Loss Rate (%) Packet Loss Rate (%) (b) Perodc INTRA updatg. (c) RD optmal INTRA updatg. 7/8/03 ICME

13 Smulato Results Observatos The proposed SCP_CII method cosstetly offers the best performace, whch proves our prevous aalyss. Whe INTRA updatg s more effectvely performed, smaller gas are acheved by SCP_CII over EP. Hece, the ga depeds o how much damage of packet loss s ot accouted for the covetoal scheme. Smlar results also hold for other testg sequeces, e.g., carphoe, mss_am, salesma, etc. 7/8/03 ICME

14 Demo Covetoal predcto based o ecoder recostructo (PSNR = 25.06dB) Source-chael predcto based o expected decoder recostructo (PSNR = 26.72dB) Forema, QCIF, 30f/s, 300kb/s, packet loss rate = 10%, perodc Itra update. 7/8/03 ICME

15 Coclusos Novelty: the proposal of further ehacemet of error reslece va fudametal modfcato of the covetoal predcto structure. Source-chael predcto based o expected decoder recostructo, whch uses ROPE to get accurate estmate of decoder quattes. I spte of the loss source codg ga due to the lower source predcto qualty, our scheme acheves better overall R-D tradeoff tha the covetoal scheme. We detfy the subtle pots selectg the moto estmato crtero, ad shows that t s advatageous to use the crtero of mmzg the expected predcto error. 7/8/03 ICME

16 Thaks! 7/8/03 ICME

Point Estimation: definition of estimators

Point Estimation: definition of estimators Pot Estmato: defto of estmators Pot estmator: ay fucto W (X,..., X ) of a data sample. The exercse of pot estmato s to use partcular fuctos of the data order to estmate certa ukow populato parameters.