Efficient Reverse-Play Algorithms for MPEG Video With VCR Support

Chang-Hong Fu, Yui-Lam Chan, and Wang-Chi Siu

CSVT 2006

Outline

Introduction MB-Based Reversed-Play Video

Streaming System Simulation Results Ideas of Backward Macroblocks

Introduction (1)

Environments

Stored videos

Limited storage:1. Displayed buffer2. Reference buffer

server

clients

Introduction (2)

Transmission of stored videos Download mode

Downloading the entire video before playback

Unacceptable delay time Streaming mode

Playing the video while downloading it Hardly supporting VCR functionality due

to the frame structure in MPEG standardsI P P P…

Introduction (3)

0..n-1

n-1

0..n-2

I …

0 1 2 n LL-1

P P P P I…

Current frame

Introduction (4) Bandwidth requirement for forward

play/reverse play

Total sent frames for playing a GOP reversely: (Average: )

L = 151.5 Mb/s30fps

151413

MB-Based Reversed-Play Video Streaming System (1) MB-based reversed-play algorithm

MBs are categorized into several classes

Transmission of some MBs can be avoided Some redundant MBs need not be decoded Increasing the complexity of the server to

reduce the client load and network load

n-2 n-1 n

Next to be displayed

1

2 3

3mv

mv

MB-Based Reversed-Play Video Streaming System (2) BMB (Backward-MB) and FMB

(Forward-MB) BMB: mvn

(k,j) = (0, 0) MBn-1(k,j) is a BMB

Percentage of BMBs

MBn(k,j) = MBn-1

(k,j) + en(k,j)

MBn-1(k,j) = MBn

(k,j) - en(k,j)

The server transmits VLC{Q[DCT(-en

(k,j))]} to the decoder

nth frame kth row and jth column

MB-Based Reversed-Play Video Streaming System (3)

Encoding of -en(k,j) at the server

DCT(-en(k,j)) = -DCT(en

(k,j)) Q[DCT(-en

(k,j))] = -Q[DCT(en(k,j))]

VLC{Q[DCT(-en(k,j))]} = ?

Sign FLC

10 2’s complement

MB-Based Reversed-Play Video Streaming System (4)

Non-MC FMB mvn-1

(k,l) = 0 MBn-1(k,l) is a non-MC FMB

MBn-1(k,l) = MC(mvn-2

(k,l)) + en-2(k,l) + en-1

(k,l)

Q[DCT(en-2

(k,l) + en-1(k,l))] = Q[DCT(en-2

(k,l))] + Q[DCT(en-1(k,l))]

The server transmits VLC{Q[DCT(en-2(k,l) + en-1

(k,l))]} to the decodere1 e2 e3 e4

MB-Based Reversed-Play Video Streaming System (5)

Simulation results (1)

MPEG-2 coder GOP size = 15 with only I-frames

and P-frames 30 fps with 200 frames CIF or SIF (Salesman, Table tennis,

and Football) and QCIF (Claire, Grandma, and Carphone) format

Simulation Results (2)

BMB

Non-MC FMB

(Sign Inversion)(DCT Addition)

Simulation Results (3)

Simulation Results (4)Salesman 1.5Mb/s

Carphone 128kb/s

nn-1n-2n-3n-4n-5

BMB

Simulation Results (5)

Ideas of BMBs

Error concealment of BMBs Encoding residual of BMBs