an improved unequal error protection technique for the wireless transmission of mpeg-4 video bo yan,...
DESCRIPTION
3 Introduction To make the compressed bitstream more robust to channel errors, the MPEG-4 video compression standard has incorporated several error resilience tools Among these techniques, the traditional unequal error protection (T-UEP) technique is the most popular, which can protect the different parts on a MPEG-4 video packet (VP) with different channel coding rates based on rate-compatible punctured convolutional (RCPC) codes However, this technique is not powerful enough for this application due to performance issuesTRANSCRIPT
An improved unequal error protection technique for the wireless transmission
of MPEG-4 Video
Bo Yan, Kam Wing NGThe Chinese University of Hong Kong
ICICS-PCM 2003
Presenter: Joungsik Kim
2
Contents
Introduction Related Techniques The Proposed I-UEP Technique Simulation Results Conclusion
3
Introduction To make the compressed bitstream more robust to channel e
rrors, the MPEG-4 video compression standard has incorporated several error resilience tools
Among these techniques, the traditional unequal error protection (T-UEP) technique is the most popular, which can protect the different parts on a MPEG-4 video p
acket (VP) with different channel coding rates based on rate-compatible punctured convolutional (RCPC) codes
However, this technique is not powerful enough for this application due to performance issues
4
Related Techniques
Error-resilient Coding in MPEG-4 Video packet resynchronization Data partitioning (DP) Reversible variable length codes Header extension code (HEC)
5
Video Packet Resynchronization
Using resynchronization marks to recover synchronization with the encoder
Maker k
Resync.maker
MBno QP HEC Combined motion and DCT data
Organization of the data within a Video Packet
6
Data partitioning
Data partitioning mode To avoid discarding all the video data in the VP Motion part / Texture part
Separated by a motion boundary maker (MBM)
Resync.maker
MBno QP HEC Motion data MBM DCT data
COD1 MCBPC1 MVx1 MVy1 COD2 COD3 MCBPC3 MVx3 MVy3
Bits Components with data partitioning in the MPEG-4 VP
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RCPC Codes
Convolutional code The current output block depends on
Information bits in the current input block and one or more previous input blocks
Input Stream k
n
EncodeV blocksCoded Stream
Structure of a General Convolutional Code
8
The relationship of the pth coded block to the input data block k-1 k-1
( ) (0) ( ) (1) ( 1)
j=0 j=0
k-1( 1) ( ( 1))
j=0
v-1 k-1( ) ( )
l=0 j=0
k-1 v-1( ) ( )
j=0 l=0
k-1(0)
j=0
, 0 1
[
p p pi ij j ij j
v p vij j
l p lij j
l p lij j
ij
C g d g d
g d
g d i n
g d
g g
(1) (2) 2
( 1) 1 ( )
( )
]
[ ( )]
ij ij
v v pij j
p
D g D
g D d
d G D
(n,k,v) code:
Puncturing Matrixes for Different Code Rate
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The T-UEP Technique T perform the T-UEP in the compressed video streams,
The “data partitioning tool” is exploited in the video packet For video packet, the information bits are divided into three pa
rtitions, each of which has a different sensitive channel errors
R1<R2<R2 To realize it, the Rate Compatible Punctured Convolutional (RCP
C) codes are used
VP Header DC DCT data AC DCT data
VP Header Motion data Texture data
I-VOP
P-VOP
R1 R2 R3
The Structure of T-UEP for I-VOP and P-VOP
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The Proposed I-UEP Technique
Focus on error protection in the motion data
Four different data types in the motion part COD: to indicate whether certain MB is coded or not MCBPC: variable field used to indicate the mode of the M
B MVx: the x component of the MV MVy: the y component of the MV
These four data types use different codebooks for variable-length decoding.
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1 0 0 0 1 0 0 0 1 1 0 0 1 1COD COD
0 0 0 0 1 0 0 0 1 1 0 0 1 1
MCBPC MVx MVy
COD MCBPC MVx MVy
Original:
After error:
error bit
The Changed Data Types by Bit Errors in the motion part
COD1 MCBPC1 MVx1 MVy1 COD2 COD3 MCBPC3 MVx3 MVy3 ……
COD1 MCBPC1 MVx1 MVy1COD2 COD3 MCBPC3 MVx3 MVy3 …………
Motion part
Motion partCode part
BeforeReorganizati
on
AfterReorganizati
on
Reorganize the Motion Part in the VP
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Thus the VP can be partitioned into four parts: VP header, COD part, Mode part and Texture part
R1<RCOD<RMode<R3
VP Header Motion data Texture data
R1 RMode R3
COD part
RCOD
The Structure of the I-UEP technique
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Simulation results
For T-UEP R1 = 1/3 R2 = 4/7 and R3 = 4/5
For I-UEP R1 = 1/3 RCOD = 1/2 RMode = 2/3 and R3 = 4/5
Foreman Sequence Simulation Result(a) T-UEP; (b) I-UEP
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Conclusion
The I-UEP proposed to strengthen the robustness of the transport of MPEG-4 video over wireless channels Reorganizes the components in the VP and
partitions it into four parts. Thus the COD bits can be more protected with
lower code rate than other bits in the motion part
After applying it, the decoded video quality can be improved significantly after transmission over noisy wireless channels