Adaptive Pre-Interpolation Filter for Motion-Compensated Prediction

Transcription

1 Adaptve Pre-Interpolaton Flter for Moton-Compensated Predcton Je Dong and Kng Ng Ngan Department of Electronc Engneerng The Chnese Unverst of Hong Kong ISCAS011 Ma Ro de Janero Brazl

2 Motvaton To replace the ont use of adaptve nterpolaton flter AIF and adaptve loop flter ALF n KTA Raw Vdeo T Q Q -1 q c T -1 M Btstream I P LF DF 1 ALF m U X Adaptve Adaptve Pre-Interpolaton Flter Adaptve Loop Flter

3 Mnmze the energ of MCP error for each frame LMMSE 3 Adaptve Interpolaton Flter AIF x e x S d d x P h E dx d: Moton vector h: Interpolaton flter P: Reference frame S: Frame to be coded P 16 : Reference frame upsampled usng zero-nserton 0 n m h e ps pp n m R n m R h h: Optmzed nterpolaton flter R pp : Autocorrelaton of P 16 R ps : Moton-compensated cross-correlaton of P 16 and S

4 Adaptve Loop Flter ALF Mnmze reconstructon error for each frame LMMSE 4 e x S x R h E R: Reconstructed frame S: Frame to be coded h: Adaptve loop flter

5 Comparson of AIF and ALF Use of AIF s coeffcents Appled to the vsual data n the reference frame Reduce the MCP error most n terms of MSE Use of ALF s coeffcents Appled to the assocated vsual data n the same frame Restore the reconstructed frame most n terms of MSE 5

6 Pros and Cons AIF and ALF are mutuall complementar n three aspects 1. ALF has lower complext than AIF. AIF reduces the MCP error most whereas ALF reduces the reconstructon error most. 3. AIF has more coeffcents to code so trade-off has to be made between accurac and sze of overhead What f AIF and ALF are ontl used? Complext: Addtve Performance: Not addtve onl 1% further bt-rate reducton on average b addtonall usng ether AIF or ALF 6

7 Lmtaton of Optmal AIF 7 Mnmze the energ of MCP error for each frame LMMSE x opt e x S d d x P h E dx d: Moton vector P: Reference frame S: Frame to be coded P 16 : Reference frame upsampled usng zero-nserton h opt : optmal AIF whch conssts of 3x3 real-valued coeffcents Impossble to be used n practce

8 Adaptve Pre-Interpolaton Flter APIF Ideall desgn h I such that ~ h opt h 8

9 Adaptve Pre-Interpolaton Flter APIF Consder the deal case h opt h ~ h I h std H opt H I H std We can t desgn h I b h I H H 1 F opt std H std H opt 9

10 Optmzaton of APIF Coeffcents Mnmze the energ of MCP error for each frame ~ e E h P164x d x4 d S x dx d: Moton vector P: Reference frame S: Frame to be coded P 16 : Reference frame upsampled usng zero-nserton h ~ : nterpolaton flter composed of concatenatng h I and h std 0 h I e m n h I : APIF coeffcents R pp : Autocorrelaton of P 16 R ps : Moton-compensated cross-correlaton of P 16 and S 10

11 Codng APIF Coeffcents 7x7-tap wth pont smmetr 5 coeff. to code for each frame Temporal predcton Predcton error Unforml quantzed to 1 steps Coded usng order-4 Exp-Golomb Codes Coeffcents pont smmetr n APIF Order-4 Exp-Golomb Codes 11

12 Comparng APIF wth AIF and ALF Reduce the MCP error lke AIF Appl to nteger pxels onl Less complext than AIF No trade-off made between the accurac and the sze of overhead 1

13 Rate-Dstorton Performance Bt-rate reducton n IPPP-coded sequences % 13

14 Rate-Dstorton Performance Bt-rate reducton n IBBP-coded sequences % 14

15 Complext Analss Assume a straghtforward mplementaton Pxels to be nterpolated are classfed nto fve categores accordng to the order the pxels are generated Total number of operatons N Total =N Int +N HalfI +N HalfII +4N QuarI +8N QuarII Arthmetc operatons for nterpolatng one frame X: number of pxels n a frame K: tmes a reference frame s referred 15

16 Concluson Appled to the nteger pxels n the reference frames such that h mnmzes the MCP error. I h std Preserve the merts of AIF and ALF and overcome ther drawbacks. Outperform ether AIF or ALF Comparable performance of the ont use of AIF and ALF Low complext 16

17 THANK YOU! 17