Distributed Video System realized on mobile device with efficient Feedback channel...
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Distributed Video System realized on mobile device with efficient Feedback channel分散式影像編碼在手機上的實現與有效率的回饋通道Chen, chun-yuan 陳群元Advisor: Prof. Wu, Ja-Ling 吳家麟 教授2012/6/28
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Outline
Motivation and introduction DVC architecture overview DVC architecture with mobile device Propose an efficient feedback channel Transcoding Experiment Result Conclusion Future work
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Motivation
Video communication is essential in Mobile device
Decrease the coding time and battery consuming on mobile.
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Introduction
For Mobile device video codec Conventional video coding (ex:MPEG-4 H.264)
Heavy weight encoder, light weight decoder. Distributed Video Coding
Light weight encoder, heavy weight decoder.
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Conventional video codec
Encoding Decoding
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DVC to H.264 Transcoder
Clouding server:DVC to H.264 transcoder
DVC encoderH.264 decoder
Feedback channel
Parity bits
Encoded sequence
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DVC codec baseline: DISPAC+DVC transcoder
1.Encoder2.Decoderno feedback channel !
Tse-Chung Su. Yun-Chung Shen. and Ja-Ling Wu. 2011. Real-time Decoding for LDPC Based Distributed Video Coding. National Taiwan University
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Time complexity analysis without feedback channel
DVC Decoding without Feedback channel Side-Information generation LDPCA
time ratio
SI generationLDPCA Decetc.
31%
Total decoding time: 17.10 sec
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Time complexity analysis with feedback channel
DVC Decoding Side-Information generation Send-Request at Feedback channel LDPCA
time ratio
SI generationLDPCA DecFeedback channeletc.
1%
95%Bottle neck!
Total decoding time: 330.51 sec
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Outline
Motivation and introduction DVC architecture Overview DVC architecture with mobile device Propose an efficient feedback channel Transcoding Experiment Result Conclusion Future work
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Distributed Video Codec
DCT
levelQuantizer
WZ Frames
𝑋𝑘
LDPCA Encoder
Buffer LDPCA Decoder
Key FramesConventional
IntraframeEncoder
Conventional Intraframe
Encoder
SI generation&refinement
DCT
SI ReconstructionBitplanes
Mode selection
CRCCRC
check
CRC-8
WZ bitstream
Feedback channel
Correlation Noise
Modeling
IDCT&Deblocking filter
Decoded WZ Frames
Decoded Key Frames
WZFrame
WZFrame
WZFrame
GOP size 4
KeyFrame
KeyFrame
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Outline
Motivation and introduction DVC architecture overview DVC architecture with mobile device Propose an efficient feedback channel Transcoding Experiment Result Conclusion Future work
Distributed Video Codec with mobile
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DCT
levelQuantizer
WZ Frames
𝑋𝑘
LDPCA Encoder
Buffer LDPCA Decoder
Key FramesConventional
IntraframeEncoder
Conventional Intraframe
Encoder
SI generation&refinement
DCT
SI Reconstruction
Bitplanes
Mode selection
CRCCRC
check
CRC-8
WZ bitstream
Feedback channel
Correlation Noise Modeling
IDCT&Deblocking filter
Decoded WZ Frames
Decoded Key Frames
Transcode Decoded Video sequenceWith specific form
Video deliver
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DVC Encoder Realization
Implement DVC encoder on Mobile Key frame encoding WZ frame encoding Efficient intra mode realization
Feedback channel transmission Network connection between mobile and server Determine payload of a packet with LDPCA
protocal
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Key frame encoding on Mobile
Previous ver. use JM9.5 Transcoder ref x.264 on PC
x.264 lib
Cross compilerKeyframe encoding
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DVC Encoder Realization
Implement DVC encoder on Mobile Key frame encoding WZ frame encoding Efficient intra mode realization
Feedback channel transmission Network connection between mobile and server Determine payload of a packet with LDPCA
protocal
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WZ coding with NDK
Native code
DVC encoder
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DVC Encoder Realization
Implement DVC encoder on Mobile Key frame encoding WZ frame encoding Efficient intra mode realization
Feedback channel transmission Network connection between mobile and server Determine payload of a packet with LDPCA
protocal
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Efficient intra block coding
Previous ver. Transcoder Use JM code. Intra block encoding consumes lots of time
in encoding.
Clouding server:DVC to H.264
transcoder
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DVC Encoder Realization
Implement DVC encoder on Mobile Key frame encoding WZ frame encoding Efficient intra mode realization
Feedback channel transmission Network connection between mobile and server Determine payload of a packet with LDPCA
protocal
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Network connection
Create network connection to connect remote server. TCP socket in C
Clouding server:DVC to H.264
transcoder
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DVC Encoder Realization
Implement DVC encoder on Mobile Key frame encoding WZ frame encoding Efficient intra mode realization
Feedback channel transmission Network connection between mobile and server Determine payload of a packet with LDPCA
protocal
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ACK at Feedback channel
TCP socket
…
syndromes
Send syndrome
Request
syndromessyndromes
syndromes
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Consuming time atFeedback channel
Packet header occupy large part of network bandwidth.
Network latency in communication at Feedback channel
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Outline
Motivation and introduction DVC architecture with mobile device DVC architecture overview Propose an efficient feedback channel Transcoding Experiment Result Conclusion Future work
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Efficient feedback channel
we propose two methods to decrease time consuming at feedback channel. Estimate the syndromes size per WZ frame Estimate the syndromes size per bitplane
Average number of requests per bitplane
1234567123456123456123451234512345123412341234123412312312312120
200
400
600
800
1000 bit rate
bit rate
DC AC1 AC2 AC3 AC4 AC5 AC6 AC7 AC8 AC9AC10AC11
AC12AC13
AC14
Bitplane Number
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Estimate the syndromes size per WZ frame
Estimate syndromes size by correspond WZ frame in previous GOP
Ex. GOP 4 Key
frameKey
frameWZ
frameWZ
frameWZ
frame
First GOP
Key frame
Key frame
WZ frame
WZ frame
WZ frame
Second GOP
formula
(ESbt)WZn=(Sbt)WZ(n-GOPsize)
WZn means the WZ frame’s index n-GOPsize means the correspond WZ frame in
the previous GOP. bt is the bitplane index. (ESbt)WZn means the estimated syndromes bit for
the bt’th bitplane of WZn frame. (Sbt)WZ(n-GOPsize) means the syndromes bit for the
bt’th bitplane of WZ(n-GOPsize) frame
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Efficient feedback channel
we propose two methods to decrease time consuming at feedback channel. Estimate the syndromes size per WZ frame Estimate the syndromes size per bitplane
Number of requests per bitplane per band
1234567123456123456123451234512345123412341234123412312312312120
200
400
600
800
1000 bit rate
bit rate
DC AC1 AC2 AC3 AC4 AC5 AC6 AC7 AC8 AC9AC10AC11
AC12AC13
AC14
Bitplane Number
Number of requests per bitplane per band
1234567123456123456123451234512345123412341234123412312312312120
200
400
600
800
1000 bit rate
bit rate
DC AC1 AC2 AC3 AC4 AC5 AC6 AC7 AC8 AC9AC10AC11
AC12AC13
AC14
Bitplane Number
Estimate by previous bands
1.formula 2.time ratio
Number of requests per bitplane per band
1234567123456123456123451234512345123412341234123412312312312120
200
400
600
800
1000
bit rateestimated bit rate
DC AC1 AC2 AC3 AC4 AC5 AC6 AC7 AC8 AC9AC10AC11
AC12AC13
AC14
Bitplane Number
formula
(ESacn bt)WZn= ( Sdc bt-1 )WZn
WZn means the n’th WZ frame. acn means the n’th AC band. bt means the bitplane index of this AC band. Which ESacn
bt mean the estimated syndrome size for the bt’th bitplane in n’th AC band.
dc means the DC band. Sdc bt-1 means the syndromes bits for bt-1’th
bitplane in DC band.
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Outline
Motivation and introduction DVC architecture overview DVC architecture with mobile device Propose an efficient feedback channel Transcoding Experiment Result Conclusion Future work
Transcode to mobile codec
Because DVC only encode luminance part in YUV, so we got only Y for output.
Our mobile device can only read mp4 and 3gp.
Y
U V
R G BFrame 1Frame 2Frame 3Frame4Frame 5Frame 6Frame 7Frame n.mp4
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Outline
Motivation and introduction DVC architecture overview DVC architecture with mobile device Propose an efficient feedback channel Transcoding Experiment Result Conclusion Future work
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Experiment Result
規格 實驗數據 :
時間 (&decode) 、 packet 數量 ( 傳幾次 )+
Test condition
12 CPU, 24 processor Intel(R) Xeon(R) CPU X5650 @ 2.67GHz
GPU: Tesla M2050 Mobile device: HTC sensation
Test sequences :
QCIF, 15Hz, all frames GOP Size 2, 4 and 8 Only luminance component is used
Test materials
Soccer Foreman Coastguard Hall Monitor
Motion: High Low
Speed up
Bitrate
RD curve
Foreman with LRSS,GOP8
RD curve
Hall monitor with LRSS,GOP8
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Outline
Motivation and introduction DVC architecture overview DVC architecture with mobile device Propose an efficient feedback channel Transcoding Experiment Result Conclusion Future work
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Conclusion
We combine DISPAC and transcoder, then port it’s encoder on mobile.
Implement and propose Feedback channel. Record video with mobile device’s camera. Transcode the decoded sequence to mobile
codec.
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Outline
Motivation and introduction DVC architecture overview DVC architecture with mobile device Propose an efficient feedback channel Transcoding Experiment Result Conclusion Future work
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Future Work
Take a more precise estimation of syndrome size.
Use motion information to estimate the syndrome size.
Build a reliable DVC codec which is loss tolerant.
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Thank You
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To do
Real time decoder Efficient intra coding Print MSG on Mobile
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DVC decoding time
Side Info Creation: 0.85 sec Overcomplete Transform: 2.35 sec Correlation Noise Modeling: 2.33 sec Conditional Bit Prob Compute: 0.60 sec Update Side Info: 7.14 sec Ldpca Decode: 123.34 sec Motion Learning: 1.79 sec Others: 1.80 sec
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Distributed Video Codec
DCT
levelQuantizer
WZ Frames
𝑋𝑘
LDPCA Encoder
Buffer LDPCA Decoder
Key FramesConventional
IntraframeEncoder
Conventional Intraframe
Encoder
SI generation&refinement
DCT
SI ReconstructionBitplanes
Mode selection
CRCCRC
check
CRC-8
WZ bitstream
Feedback channel
Correlation Noise
Modeling
IDCT&Deblocking filter
Decoded WZ Frames
Decoded Key Frames
Distributed Video Codec with mobile
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DCT
levelQuantizer
WZ Frames
𝑋𝑘
LDPCA Encoder
Buffer LDPCA Decoder
Key FramesConventional
IntraframeEncoder
Conventional Intraframe
Encoder
SI generation&refinement
DCT
SI Reconstruction
Bitplanes
Mode selection
CRCCRC
check
CRC-8
WZ bitstream
Feedback channel
Correlation Noise Modeling
IDCT&Deblocking filter
Decoded WZ Frames
Decoded Key Frames
Transcode Decoded Video sequenceWith specific form
Video deliver
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Video recodeWith mobile camera
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ACK at Feedback channel
…
Send syndrome
LDPCA Encoder
&CRC
LDPCA Decoder
&CRC
Syndromes for one bitplane
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ACK at Feedback channel
…
Request
LDPCA Encoder
&CRC
LDPCA Decoder
&CRC
Syndromes for one bitplane Decoding one bitplane
with received syndromesAnd chack CRC
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ACK at Feedback channel
…
Send syndrome
LDPCA Encoder
&CRC
LDPCA Decoder
&CRC
Syndromes for one bitplane
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Contribution
Realize DVC encoding part on Mobile device Implement Feedback channel Implement encoder’s component with x264 Propose an efficient Feedback channel Transcode the decoded sequence to mobile
codec
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Outline
Motivation and introduction DVC architecture with mobile device Propose an efficient feedback channel Transcoding Experiment Result Conclusion Future work