Proxy-Based Reference Picture
Selection for Error Resilient
Conversational Video in Mobile
Networks
Wei Tu and Eckehard Steinbach, IEEE Transactions
on Circuits and Systems for Video Technology, VOL.
19, NO. 2, February 2009.
Reporter：陳志明
Outline
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Introduction
Related Works
Proxy-Based Reference Picture Select
Simulation Results
Conclusion
Introduction
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Conversational video requires very low delay.
Decoding of erroneous or incomplete video bit-stream
leads to severe quality degradations.
Numerous studies have been performed to improve the
error resiliency for video transmission over lossy
channels.
Scenarios :
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Uplink
Downlink
Both
Introduction (con.)
Related Works
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Error resilience schemes used for comparison
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Random intra-MB update(RIMU)
Feedback multidecoder distortion estimation(F-MDDE)
NEWPRED
RESCU
RIMU
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One way to stop temporal error propagation is the
periodic insertion of Intra-coded pictures or macroblocks
(MBs).
There is no feedback information available. However,
without accurate information about the channel statics,
the efficiency of RIMU is limited, if the packet loss rate
changes rapidly over a wide range.
F-MDDE
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A powerful yet computationally demanding method is
introduced to estimate the excepted reconstruction
distortion.
If K is not large enough, the estimation will be inaccurate
and affects the distortion estimation for later frames.
NEWPRED
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NEWPRED uses the feedback about lost packets or
correctly received packets to prevent the prediction from
those image areas that have been corrupted.
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A-NEWPRED
N-NEWPRED
NEWPRED(con.)
RESCU
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RESCU is to change the frame dependencies in a video
sequence such that a retransmission of lost information
can be used for error recovery.
Proxy-Based Reference Picture Select
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It have three scenarios.
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Downlink Error Recovery
Uplink Error Recovery
Combination Both
Downlink Error Recovery
Error propagation for FDRPS when frame is corrupted.
Uplink Error Recover
Adaptive RPS triggered by feedback from the base station to the sender
Combination Both
Error robust mobile video telephony using the proposed PRPS framework
Simulation Results
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H.264/AVC test software version JM 11.0
Test video :
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Video frame structure :
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The first 300 frame of the test video Foreman QCIF at 15fps
The first 300 frame of the test video Salesman QCIF at 15fps
I-P-P-P-I-…
Max RTT on the uplink and downlink are 200 ms(RTT = 3).
The end-to-end round-trip delay(including the wireless and
wireline networks ) is 400 ms(RTT = 6).
RIMU
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RD performance of RIMU for the Foreman sequence and
1% random packet loss in both uplink and downlink.
F-MDDE
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RD performance of MDDE and F-MDDE with for the
Foreman sequence and 1% random packet loss in both uplink
and downlink.
F-MDDE (con.)
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RD performance of F-MDDE for a RTT of 6 frames for
the Foreman and Salesman sequences.
NEWPRED
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RD performance of NEWPRED for the Foreman sequence
for different RTTs.
RESCU
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RD performance of RESCU for the Foreman sequence for
different RTTs.
Adaptive RPS
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Performance of the adaptive RPS schemes used for uplink
error recovery, Foreman, RTT of 3 frames.
Proxy-Based Reference Picture Select
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RD performance of PRPS as a function of the RTT on the
uplink and downlink for a 5% packet loss channel. The
mean burst length is 5 packets. The test sequence is
Foreman.
The comparison (Foreman sequence)
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Performance of PRPS and the comparison schemes for
the Foreman sequence.
The comparison (Salesman sequence)
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Performance of PRPS and the comparison schemes for
the Salesman sequence.
The comparison (Packet loss rate and PSNR)
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Mean reconstruction quality as a function of packet loss
rate for a mean packet burst loss length of 5 for the
Foreman sequence.
The comparison (uplink and downlink)
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5% burst packet loss either on the uplink or the downlink
for the Foreman sequence at 150 kbps including all
overheads.
we give the performance when either a wireless uplink or
a wireless downlink is involved in the end-to-end
transmission.
Conclusion
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Feedback information between the mobile user and colocated base stations significantly decreases the feedback
delay, and thus greatly improves the efficiency of error
recovery.
The prediction distance is adjusted to the RTT of the
downlink which gives us the opportunity to retransmit
lose packets and to use retransmitted packets to stop
error propagation.
Proxy-based RPS scheme is compatible with the
h.264/AVC standard syntax and is of very low complexity
at base stations.