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 !!