Systematic Lossy Error Protection based on H.264/AVC Redundant Slices

Systematic Lossy Error Protection based on H.264/AVC Redundant Slices

Shantanu Rane and BernShantanu Rane and Bernd Girodd Girod

Information Systems Information Systems LaboratoryLaboratorySStanford Universitytanford University

S. Rane and B. Girod – SLEP based on H.264/AVC redundant slices – VCIP 2006 2

Error-Resilient Video TransmissionError-Resilient Video Transmission

Channel Error Probability

Vid

eo

Qua

lity

FEC cliff effect

Layered video coding with Priority Encoding Transmission (PET)

Systematic Lossy Error Protection(SLEP) using Wyner-Ziv coding [Rane, Girod, ICIP 2004-05]

Construct Wyner-Ziv codec using H.264/AVC redundant slices

S. Rane and B. Girod – SLEP based on H.264/AVC redundant slices – VCIP 2006 3

Systematic lossy source/channel coding

SLEP implementation based on H.264/AVC redundant slices

Simulation results

OutlineOutline

S. Rane and B. Girod – SLEP based on H.264/AVC redundant slices – VCIP 2006 4

[Shamai, Verdú, Zamir, 1998]

Enhancing analog image transmission using digital side information

[Pradhan, Ramchandran, 2001] Error-resilient distributed video compression schemes

[Sehgal, Ahuja, 2003-04], [Xu, Xiong, 2004] Systematic lossy source-channel coding of video waveforms

[Aaron, Rane, Girod, 2003-04-05]

Encoder Digital Channel

Decoder

Analog Channel

Wyner-ZivEncoder

Sideinfo

Wyner-ZivDecoder

Digital Channel

Systematic Lossy Source/Channel CodingSystematic Lossy Source/Channel Coding

S. Rane and B. Girod – SLEP based on H.264/AVC redundant slices – VCIP 2006 5

“Analog Channel”

S S’

S*

Video EncoderVideo Decoder with Error Concealment

Err

or-P

rone

cha

nnel

Wyner-Ziv Decoder

Coarse Quantizer

Wyner-Ziv Encoder

ReconstructionSlepian-

Wolf Encoder

Slepian-Wolf

Decoder

Side information

SLEP for Video TransmissionSLEP for Video Transmission

Analogous to systematic source/channel coding Error corrected up to a distortion introduced by coarse WZ quantizer,

hence lossy protection [Rane, Aaron, Girod, ICIP 2003]

S. Rane and B. Girod – SLEP based on H.264/AVC redundant slices – VCIP 2006 6

Encode Redundant Pic

(Requantize)

Entropy Decoding

SLEP using H.264/AVC Redundant SlicesSLEP using H.264/AVC Redundant Slices

WYNER-ZIV ENCODER WYNER-ZIV DECODER

Err

or-p

rone

Cha

nnel

Decode Redundant Slice

Motion vecs +Coding modes

RSDecoder

Side info

Motion vecs +Coding modes

QP

Recovered motion vectorsfor erroneously received

primary slices

EncodePrimary Pic

Q-1 T-1

MC

H.264/AVC DECODER

+Entropy Decoding

OutputVideo

H.264/AVC ENCODERInputVideo

Encode Redundant Pic

(Requantize)

RSDecoder

Parity slicesQP

S. Rane and B. Girod – SLEP based on H.264/AVC redundant slices – VCIP 2006 7

Reed-Solomon Coding Across Video SlicesReed-Solomon Coding Across Video Slices

1 byte in slice

filler byte

parity byte

RS code across slices

Transmit only parity symbols

XX X X X X X X X X X X X Xkn

Erasure Decoding

S. Rane and B. Girod – SLEP based on H.264/AVC redundant slices – VCIP 2006 8

Experimental SetupExperimental Setup

Systematic Transmission H.264/AVC primary coded bitstream WZ Codec Redundant slices + Reed-Solomon Slepian-Wolf codec Same slice boundaries for primary and redundant slices GOP structure : I-B-P-B-P-… Unequal WZ protection for B and P frames Previous frame concealment

S. Rane and B. Girod – SLEP based on H.264/AVC redundant slices – VCIP 2006 9

2 4 6 8 1031

32

33

34

35

36

% of slices lost

PS

NR

(dB

)

encoder, QP 28, 408 kbps

Resilience using Redundant SlicesResilience using Redundant Slices

0

100

200

300

400

500

600

700

800

900

28 32 36 40 44 48

QP of redundant description

Tot

al b

it-ra

te (

kbps

)

Redundant descriptionPrimary description

Video Quality Total Encoding Rate

QP 48

QP 44

QP 40

QP 36

QP 32

S. Rane and B. Girod – SLEP based on H.264/AVC redundant slices – VCIP 2006 10

SLEP based on Redundant Slices (SLEP based on Redundant Slices (ForemanForeman))

Transmit WZ coded version of Transmit WZ coded version of the video signalthe video signal WZ bit-rate ~ 10% of bit-rate of WZ bit-rate ~ 10% of bit-rate of the primary descriptionthe primary description Coarser redundant description Coarser redundant description has stronger error-resilience but has stronger error-resilience but greater quantization mismatchgreater quantization mismatch

Primary (systematic) description @ 408 kbps

with QP 28.0

100

200

300

400

500

600

700

800

900

28 28 32 32 36 36 40 40 44 44 48 48

Transmitted WZ bit-rate

Full redundant bit-rate

Transmitted systematic bit-rate

QP of redundant description

To

tal t

ran

smitt

ed b

it-ra

te (

kbp

s)

S. Rane and B. Girod – SLEP based on H.264/AVC redundant slices – VCIP 2006 11

SLEP based on Redundant Slices (SLEP based on Redundant Slices (ForemanForeman))

Video quality for various redundant descriptionsSymbol error probability = 5 x 10-4

20 40 60 80 100

24

26

28

30

32

34

36

Frame number

PS

NR

(d

B)

Encoder reconstruction @ 408 kbps

Error concealment only

FEC

QP36

QP48

QP40

Systematic bit-rate 408 kbps, WZ bit-rate ~ 40 kbpsSymbol error probability = 5 x 10-4

Error-freeError-free35.7 dB35.7 dB

Error concealment onlyError concealment only40 kbps FEC40 kbps FECSLEP with redundant QP = 36SLEP with redundant QP = 36SLEP with redundant QP = 40SLEP with redundant QP = 40SLEP with redundant QP = 48SLEP with redundant QP = 4820.9 dB20.9 dB25.5 dB25.5 dB30.9 dB30.9 dB34.2 dB34.2 dB32.9 dB32.9 dB

S. Rane and B. Girod – SLEP based on H.264/AVC redundant slices – VCIP 2006 13

SummarySummary

SLEP based on H.264/AVC redundant slices support Trade-off between error resilience and quantization mismatch

introduced by redundant description Graceful degradation of received video quality compared to FEC

Recent work– H.264/AVC rate control to modulate QP of redundant

description– SLEP on region-of-interest using Flexible Macroblock

Ordering (FMO)