4. H.263 Video Codec for Low Bitrate Communcationsvada.skku.ac.kr/ClassInfo/microsystem/multimedia/4h2… · · 2002-04-04H.263 Video Codec for Low Bitrate Communcations 1998

Chosun Univ. Multimedia ASIC Lab. 1

http://vlsi.chosun.ac.kr

4. H.263 Video Codec for Low Bitrate Communcations

1998. 02. 18.

/ß¿�� ÃOÔ³t�´�» MEDALMultimedia Engineering & Design ASIC Lab.

3 Ô Ã[email protected]




H.263 Overview

• ¬¤1 Y��(èD�� ¨ø�, ØÄ�)è �M�È¸È/è¸È ÀèHtÀ }¥e¹� ù9üÔ¨��¤

• ¬¤1 Y��tÀü ä��¸X ÀèH ¨�Ô�D ÀX �¤� H.324 �tÀ PM¼�, ¤õü8ðÕù9�¤ä G.723.1��.

• H.261è Ô¼à� 4Àü Ä�$Üø Í9� L¤Ì

• ¥e��: 5)ü(sub-QCIF, QCIF, CIF, 4CIF, 16CIF)



H.263 Overview

Coding control

Sourcecoder

Sourcedecoder

Video multiplexcoder

Video multiplexdecoder

Transmissionbuffer

Receivingbuffer

Codedbitstream

Videosignal

a) Video coder

b) Video decoder

External control



H.263 Overview

• 8 ]y ³ Ä� ÔI– Forced updating: Pátü ¥MB8 �0� 132, µ �,ä INTRA$Üø– Buffering: Hypothetical Reference Decoder¤ <P� ¼ ,è ¹h– Forward Error Corection: BCH(511,493)– Fast Update Request/Freeze Picture Request/Freeze Picture Release– Multipoint Operation: CPM(Continuous Presence Multipoint)– Negotiable Coding Options

* Unrestrcted Motion Vector modeá<ü �¡th MV lM; 5ä áttÀ átü edge Ô À de(� ,8 aT LÌ¥(.´� MVü 8¨ ùIü� �ø ü de(� � aT L ¥(

* Syntax-based Arithmatic Coding modeVLC TÄ$Üø� ¤X�; SNR�< �t¥eä ½à< $ÜøÌ� 6èt

* Advanced Prediction modeOverlapped Block Motion Compensation(OBMC); 4Àü MV� è\mä A¤üdp �� IeÀ¬Åè ¼-�. -, blocking effect ¨� ¤¥ ølè ÀÄ�

* PB-frames modePátä Bát ôát ü<ü �¨� $Üø�; e¤¥à�è\Ìü A¤j� ¨¬(ÌèA¤�X.



H.263 Overview

• Source FormatPicture Format

Aspact ratio8 4:3(H.261ü QCIF/CIFä ½�)Encoder: Sub-QCIF, QCIFµ ¥Xh ü< dtDecoder: Sub-QCIF, QCIF ¼�� ü� dt

Picture Format number of pixels forluminance (dx)

number of lines forluminance (dy)

number of pixels forchrominance (dx/2)

number of lines forchrominance (dy/2)

sub-QCIF 128 96 64 48

QCIF 176 144 88 72

CIF 352 288 176 144

4CIF 704 576 352 288

16CIF 1408 1152 704 576



H.263 Overview

• Source Format(conti)– Luminanceä Chrominanceü |° ¨ü

Luminance SampleChrominance SampleBlock Edge

– Sampled values : Black = 16, White = 235 Zero color difference = 128 Peak color difference = 16 and 240 coding input values: 1 ~ 254



H.263 Encoder

DCT : Descrite Cosine TransformIDCT : Inverse DCT Q : QuantizerIQ: Inverse Q VLC(C): Variable Length Coder for Transform CoefficientsVLC(M): VLC for Motion Vector MBTYPE: Macroblock Type and Pattern PRED: PredictionME1: Integer-Pel Motion Estimation and Intra/Inter Decision ME2: Half-Pel Motion Estimation M: Previous Reconstructed Frame MemoryCC: Coding Control

DCT Q VLC(C) BUF

M VLC(M)

IQ

IDCT

+_

++

Video Input

MUX

CC

PRED

ME2ME1

MBTYPE

CodedBitstream

Out

0

Intra/Inter

Video signalSide information



H.263 Decoder

Coded BitstreamInput IDCTIQVLD(C)

+Reconstructed

Video Out

MC M

+DMUXBUF

VLD(M)

MBTYPEIntra/Inter

0

VLD(C): Variable Length Decoder for Transform CoefficientsVLD(M): VLD for Motion VectorM: Previous Reconstructed Frame MemoryMC: Motion CompensationDMUX: Demultiplexer



H.263 �Óã cw{ +/

4 hÙ ��

• Picture• Group of Blocks• Macroblock• Block



H.263 �Óã cw{ �ô+/

...

GOB 0

GOB 1

GOB 7

GOB 8

9 GOBs/picturePicturesex) QCIF

144 lines/ picture

176 pixels/line

11 MBs/GOBMB MB MB MB MB

1

3

2

4

5 6

CB CR

Y 6 Blocks/MB

8x8 pels/block(zig-zag scan)



Picture Layer

PSPARE(0/8/16...)

PSC(22)

TR(8)

PTYPE(13)

PQUANT(5)

PSBI(2)

CPM(1)

TRB(3)

DBQUANT(2)

PEI(1)

GOBs(...)

ESTUF(...)

EOS(22)

PSTUF(...)

Picture Header

Picture Stuffing

PSC: Picture Start CodeTR: Temporal ReferencePTYPE: Picture TypePQUANT: Quantizer Informaton for PictureCPM: Continuous Presence MultipointPSBI: Picture Sub Bitstream IndicatorTRB: Temporal Reference for B-picture

DBQUANT: Quantization information for B-picturePEI: Extra Insertion InformationPSPARE: Spare InformationGOB: Group of BlockESTUF: Stuffing for EOSEOS: End of SequencePSTUF: Stuffing for PSC



GOB Layer

GSTUF(...)

GN(5)

GBSC(17)

GSBI(2)

GFID(2)

GQUANT(1)

MBs(...)

GOB Header

GSTUF: Stuffing for GBSCGBSC: Group of Block Start CodeGN: Group NumberGFID: GOB Sub Bitstream IndicatorGFID: GOB Frame IDGQUANT: Quantizer Information for GOBMB: Macro Block



Macro Block Layer

COD(1)

MCBPC MODB CBPB(6)

DQUANT(2)

CBPY MVD MVD2-4 MVDB BLOCKs

MB Header

COD: Coded Macroblock IndicationMCBPC: MB Type & Coded Block Pattern for ChrominanceMODB: MB mode for B-blocksCBPB: Coded Block Pattern for B-blocksCBPY: Coded Block Pattern for LuminanceDQUANT: Quantizer InformationMVD: Motion Vector DataMVD2-4: Motion Vector Data for Advanced Prediction modeMVDB: Motion Vector Data for B-macroblock



Block Layer

INTRADC(8)

TCOEFs

INTRADC DC Coefficient for INTRA blocksTCOEFF: Trnsform Coefficient

• 6 Blocks(4 luminance blocks, 2 color difference blocks)INTRADC8 MB type 3,4� MBü ¥ ¸�t �PTCOEFF8 MCBPC< CBPYt Ô �P

• PB-frameL�8 12 Blocks(6 P-blocks, 6 B-blocks)INTRADC8 MB type 3,4� MBü L� P-blockt �P, B-blockt8 jðTCOEFF8 MCBPC< CBPYt Ô P-blockt �P,

B-blockt8 CBPBt Ô �P�



?÷� èT� ï·SK

• de(¬Å L�Ä�• Macroblock Prediction• Transform• Quantization• VLC Encoding• Buffering• Buffer Regulation



��C Çà» g�ß�

• de(¬Å(ME)ä MBü Luminancet ¤�Àp ¼-Ì• Error Measure: SAD(Sum of Absolute Difference)• Integer Pixel ME

– Vectort ¤� ¸��Ô: 16 x 16, 8 x 8(at Advanced Prediction Mode)– Full search; tm¥�: ¼e/¼m +/- 15 pixelsðd

ÒÀÃ ÷ ø îñèæèíàë ïñäõèîôò ÷ ø ôï óî Í îñÍ

è é

Í Í

§ « ¨ « « ¡ ¡««

«

= − = ± == =∑° °

°´ °µ ·

ÒÀÃ ÒÀÃ°µ °µ

¯ ¯ °¯¯§ «¯¨ § «¯¨= −

– 16x16 Integer pixel MV(V0) : the lowest SAD16(x,y)– 4 8x8 integer pixel MVs(V1,V2,V3,V4): the lowest SAD8(x,y)– 16x16 ¬Å ð– Advanced Prediction ð8ÒÀÃ ÒÀÃ ÷ ø ÒÀÃ öçäñä ÒÀÃ ÒÀÃ ÷ ø

äñ ÷ ÷èíóìèí§ § « ¨« ¨« § « ¨= = ∑°µ ³ · ³ · ·

°

³

ÒÀÃ ÒÀÃ ÷ øäñèíó

§ « ¨=°µ

to favour the zero vector



Macroblock Prediction

• Prediction ModesMODE PREDICTION/DQUANT 0 INTER 1 INTER + Q 2 INTER4V 3 INTRA 4 INTRA + Q

• Chrominance Prediction, MV/2

+ Chrominance pixel position

1/4 pixel chrominance position

a=A

b=(A+B)//2

c=(A+B)//2

d=(A+B)//2

e=(A+C)//2

f=(A+B+C+D)//4

g=(A+B+C+D)//4

h=(A+B+C+D)//4

+ +A B

C D

a b c d

++

e f g h

i j k l

m n o p

i=(A+C)//2

j=(A+B+C+D)//4

k=(A+B+C+D)//4

l=(A+B+C+D)//4

m=(A+C)//2

n=(A+B+C+D)//4

o=(A+B+C+D)//4

p=(A+B+C+D)//4



Transform

• Forward 2-D DCT

Å ô õ â â å ÷ ø÷ ô ø õ

ô õ

ø÷

§ « ¨ § « ¨âîò§ ¨

âîò§ ¨= +

+

==

∑∑°

³

± °

°µ

± °

°µ¯

¶

¯

¶ π π

• Inverse 2-D DCT

å ÷ ø â â Å ô õ÷ ô ø õ

öèóç ô õ ÷ ø öçäñä âê

ê

ô õ

õô

ê

§ « ¨ § « ¨âîò§ ¨

âîò§ ¨

« « « « ««® «

«

= +

+

= ==≠

==∑∑°

³

± °

°µ

± °

°µ

¯ ° ¶° ± ¯

° ¯

¯

¶

¯

¶ π π

x,y: spatial coordinates in the pixel domain

u,v: coordinates in the transform domain



Transform

f(x,y)

Data domain Transform domain ==> 8x8 2-D DCT

followed

by...

8-point 1-D DCTalong columns

8-point 1-D DCTalong rows

• Separable 2-D DCT(column and row/row and column)

• Frequency distribution & Structural decomposition



Quantization

• INTRA DCQuant.:Dequant.:

• QunatizationINTRA AC:

INTER:

• Inverse Quantization

ËÄÕÄË Âëèïïèíæ ÂÎÄÅ=°

±´³

·®®

ËÄÕÄË Âëèïïèíæ òèæí ÂÎÄÅ ÷ ÂÎÄÅÐÏ

ÐÏ= −

−°±¶

°±¶

±±§ ¨ ®

ÑÄÂÎÍ ËÄÕÄË ÷= ·

( )( )

ÑÄÂ èå ËÄÕÄË

ÑÄÂ òèæí ËÄÕÄË ÷ ÐÏ ÷ ËÄÕÄË ÐÏ èå ËÄÕÄË ÐÏ èò îãã

ÑÄÂ òèæí ËÄÕÄË ÷ ÐÏ ÷ ËÄÕÄË ÐÏ èå ËÄÕÄË ÐÏ èò äõäí

ÑÄÂ Âëèïïèíæ ÑÄÂ

= =

= + ≠

= + − ≠

=−

¯ ¯

± ¯

± ° ¯

±¯³·

±¯³¶

«

§ ¨ « «

§ ¨ « «

( )ËÄÕÄË Âëèïïèíæ òèæí ÂÎÄÅ ÷ ÂÎÄÅ ÐÏ=−°±¶

°±¶

±§ ¨ ®

QP: Quantization Parameter(1~31)

Quantization stepsize: 2QP



VLC Encoding

• VLC Encoding of quantized transform coefficents– 8x8 blocks are scaned with “zig-zag” scanning– Lossless coding– 3-dimmential VLC(EVENT): combination of LAST,RUN, LEVEL

most commonly occuring combi. of (LAST,RUN,LEVEL): VLC remainning combination: ESCAPE(7bits)+LAST(1)+RUN(6)+LEVEL(8)

: FLC; 22 bits– Run-length Coding ¬¤¹: 0¶� �T ì,ü�.

¶: 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 3 1 2 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0

$ÜX: (0,5,1) (0,11,3) (0,0,1) (0,0,2) (1,2,1)

ø�enon-zero¶�jðè <dhnon-zero¶ �t

<Ì “0” Ó¼

$ÜXü À�ù�t Ô Huffman codingè ¼-ü�VLCð�¸è p�



Buffer Regulation

• Regulation of stepsize and frame rate– MB leveltÀ stepsize(=2QP) dø�X

ÐÏ ÐÏÁ

Á

Á

ÑÁ Á Á Á Á

ìá

ÌÁÁ

íäö è è è ìá= + +

= − = −− −°

° ±

° ° ±°±

°±∆ ∆ ∆ ∆« « «

3,��tü� $Üøü8}ì QP¤ døÌ

l�X QP¶à� �¬üÔ¨� DQUANT¶è d¹�

l�MBt dø�P QP¶

�¨átü m�QP¶

�¨áttÀ PM� è\¼

át� M�è\¼

¨P MB ,Ü

� átü MB¼

átt¤� ¨Pðd 0èÀ è\¼

è\Ì

ÐÏíäö

Ð Ïè −°

Áè −°

Á

ìá

ÌÁ

Ñ

Áè ìá«



Bufferring

• Hypothetical Reference Decoder(HRD)– $ÜÔtÀ8 HRDü 8�t �0 @É bitstreamè ÀX� �– � át¤ BPPmaxKb ¬ � ¼ jð– HRD¼�( : (B + BPPmaxKb*1024bits)

t

t

R (t)d t

B

b

n+1

n

n

n+ 1

d

n+1

t n n+1t

b

n+ 1 n

HRD bu ffe roccupancy(bit)

T im e(C IF in te rval)

N O T E – T im e (t – t ) is a n integer nu m ber o f C IF p ic tu re pe r iod s (1 /2 9 .97 , 2 /2 9 .97 , 3 /2 9 .9 7 , ...) .

Source format BPPmaxKb

sub-QCIF 64

QCIF 64

CIF 256

4CIF 512

16CIF 1024

ÁÑ= ³±¸

ìà÷

¸¶

ã á Ñ ó ãó Áí í

ó

ó

í

í

+ ≥ + −+∫°

°

§ ¨



Advanced Prediction mode

• Overlapped Block Motion Compensation(OBMC)• MB� 4 MVs¤ Ä ¼ ,ð• át ah ¼8 MV d¹ lM(UMV)• UMV¤ Ä�¼lè aTtp MV8¨ ùI• PB-framesL�ä �| ¥MÄð OBMCä Pátü ¬Åtp ¥M¼�, Bátt8 ¥MìÌ




• ��¸�� 4Àü de(EÔ– 1 or 4 MVs T¹ ---> MCBPCt d¹; 1MV aT 4MVs8 ½ä ¶– h� ¬ÅEÔ(V1/V2/V3) P¹ü�:

– Õ(ü MV:

= (sum of the 4 luminance vectors)/8ÌÕÃÂÇÑ

MV2 MV3

MV1 MV

MV2 MV3

MV1 MV

MV1

MV2 MV3

MV

MV2 MV3

MV1 MV




• Luminanceü OBMC(]� de(�e)

4 5 5 5 5 5 5 4

5 5 5 5 5 5 5 5

5 5 6 6 6 6 5 5

5 5 6 6 6 6 5 5

5 5 6 6 6 6 5 5

5 5 6 6 6 6 5 5

5 5 5 5 5 5 5 5

4 5 5 5 5 5 5 4

2 2 2 2 2 2 2 2

1 1 2 2 2 2 1 1

1 1 1 1 1 1 1 1

1 1 1 1 1 1 1 1

1 1 1 1 1 1 1 1

1 1 1 1 1 1 1 1

1 1 2 2 2 2 1 1

2 2 2 2 2 2 2 2

2 1 1 1 1 1 1 2

2 2 1 1 1 1 2 2

2 2 1 1 1 1 2 2

2 2 1 1 1 1 2 2

2 2 1 1 1 1 2 2

2 2 1 1 1 1 2 2

2 2 1 1 1 1 2 2

2 1 1 1 1 1 1 2

Ç è é¯§ « ¨

¨Pluma¸�ü MVä ¬Åè ¨� ¤µü

above/belowt ¨ü� luma¸�ü MVä ¬Åè¨� ¤µü

left/rightt ¨ü� luma¸�ü MVä ¬Åè¨� ¤µü

Ç è é°§ « ¨ Ç è é

±§ « ¨

previousblock

currentblock

above

left

right

below

Each pixel in 8x8 luma prediction block= (weighted sum of 3 prediction values)/8



Reference

• ITU-T DRAFT H.263, Video Coding for Low Bitrate Communication, 2May, 1996.

• Telenor Research(TR), VIDEO CODEC TEST MODEL, TMN5, 31Jan., 1995

• Digital Video Coding at Telenor R&D,http://www.fou.telenor.no/brukere/DVC/

• TMN H.263 Encoder/Decoder/Player v.2.0 C Sources & QCIF files,ftp://bonde.nta.no/pub/tmn/software,ftp://bonde.nta.no/pub/tmn/qcif_sources

Documents

4. H.263 Video Codec for Low Bitrate Communcationsvada.skku.ac.kr/ClassInfo/microsystem/multimedia/4h2… · · 2002-04-04H.263 Video Codec for Low Bitrate Communcations 1998