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Analysis of FEC Function for Real-Time
DV Streaming
Kazuhisa Matsuzono, Hitoshi Asaeda, Kazunori Sugiura, Osamu Nakamura, and Jun Murai
Keio University
Graduate School of Media and Governance
Introduction• Due to the widespread dissemination of high speed DSL
and FTTH, the demands of transmitting high quality audio and video data have been increased.– DVTS (Digital Video Transmission System) is used in
various research communities.• International symposium, network collaboration game, etc.
HD Camera HD Camera
studio studio
Digital Video Streaming
• Simply equipment• International symposium, network collaboration game,
and so on..• High quality and low delay and low cost
– Resolution: 720×480,1280×720, 1440×1080• average consumption bandwidth
– About 30Mbps
SenderReceiver
buffer buffer
Internet
The problem of quality reduction
• According to network condition, pktloss happens– Physical bandwidth or available bandwidth
• Σ(DVTS traffic + other traffic ) > available bandwidth– Congestion– Quality reducing
SenderReceiver
Internet
DV/RTP packet
bursty
Real-Time Streaming• Play quality vs Timeliness (interaction)
– Packet reachable Dead Line is restricted• No utilizing the large amount of buffer
– Congestion reducing play quality• Adjusting sender’s transport method to changing n
etwork condition is very difficult– Rate control– FEC
SenderReceiver
buffer buffer
Motivation
• Providing seamless and high interactive streaming on End-to-End model – taking into account high quality streaming, timeliness and high
bandwidth-delay network
• Supportive packet loss avoidance mechanism for real-time streaming application with minimal quality loss– use the network resource effectively
• Providing best possible video quality
– help reducing quality losses• Hopefully collaborate within other packet @ Internet
Video frame data Internet
sender
FEC dataChanging each rate
The relation between quality and FEC
Video quality
FEC rate
Max
Situation B
Situation A
need Rate Control!!
Optimal Point
Quality is good?
Related Work
InternetInternet Receiver
MPEGsource
MPEGsender
Change of FEC encoding rate Video Frame of pattern 1
Video Frame of pattern 2
FEC data
Change of MPEG quality
• Rate Control– TFRC (TCP Friendly Rate Control)
• DCCP (Datagram Congestion Control Protocol)
• QAFEC (quality adjusted FEC)
Design and Implementation of FEC function for DVTS
• Static FEC using Reed-Solomon CodeRTP Header PAD
DV dataFEC data
Receive buffer FEC group ID = X
DV part FEC part discard
Play buffer
FEC group ID = X+1 FEC group ID = X+2
Packet loss
Waiting for FEC data
Waiting for DV data and FEC data
Experiments
• Test bed network
Sender ReceiverDummynet
DV streaming
Sender and Receiver Dummynet
CPU Intel Pentium M 1GHz Intel Xeon 3.60GHz
Memory 512MB 3GB
OS Linux Kernel 2.6.17 FreeBSD 5.4 Release
NIC RealTech 100Base-TX Intel 1000Base-T
• Hardware in our experiment
Experimental Analysis
• Costs of encoding and decoding FEC redundancy
0% 1.0msec. 10.2msec. 11.2msec.
30% 11.8msec. 21.9msec. 33.7msec.
60% 27.1msec. 61.4msec. 88.5msec.
90% 39.7msec. 62.9msec. 102.6msec
.
FEC rate encoding decoding total
DV Frame Rate 100%
DV Frame Rate 50%
Conclusion
• Analyzing FEC function with DV streaming– It is very effective to provide the best possible
streaming quality• Using the appropriate decided frame rate and FEC
encoding rate
– The further disruption of video and audio could occurs
• deciding non-proper FEC encoding rate and frame rate toward the current bandwidth condition
Future Work
• Verify and define the algorithm– Adaptive rate control and FEC for DVTS
• Rate Control– Applied only when the network congestion is highly observed
• FEC– Protect the quality to provide best possible streaming quality
– Bandwidth estimation with packet error torelance
• Probe the best combination between FEC rate and frame rate according to the current network condition
– Packet loss rate, non-recovery rate, and the amount of receiver buffer
– Evaluate our proposed mechanism on a heterogeneous communication enviroment
Thank you !!