MediaPlayer™ vs. RealPlayer™ A Comparison of

Network TurbulenceMingzhe Li, Mark Claypool, Robert KinickiCS Department

Worcester Polytechnic InstituteWorcester, MA, USA

http://perform.wpi.edu/

November 2002 SIGCOMM Internet Measurement Workshop

Introduction• Streaming video often does not like TCP

– Wants smooth stream, so rate-based– Does not always want retransmissionsChooses UDP

• UDP flows may be unresponsive to congestionHandle with Active Queue Management (AQM)

• Typical AQMs model UDP flows as CBR (“firehose”)

• More realistic models of streaming UDP flows will make AQMs more effective

• We investigate size and distribution over time Turbulence

• Big 3: RealPlayer, MediaPlayer, QuickTime [Jup01]

November 2002 SIGCOMM Internet Measurement Workshop

Methodology

•Build automated video players (MediaTracker and RealTracker [WCZ01])– Use commercial cores– Software Development Kits (SDKs)– Record application stats: frame rate…

•Select hosts with both RealNetworks and Microsoft Media video servers

•Stream identical content to players on the same host

•Analyze results

November 2002 SIGCOMM Internet Measurement Workshop

Clip SelectionReal

MicrosoftType Bandwidth (Kbps) (Kbps)

1 Sports High 284 3233:46 Low 36 50

2 Commercial High 268 3070:39 Low 84 102

3 Sports High 284 3070:60 Low 37 38

4 Music T.V. High 181 3094:05 Low 26 50

5 News High 218 2501:47 Low 22 39

6 Movie Clip Very High 637 7312:27 High 271 347

Low 39 102

November 2002 SIGCOMM Internet Measurement Workshop

Experimental Setup

• Player Platform– Microsoft Windows 2000 PC– P4 1.8 GHz, 512M RAM, AGP 32MB video card– mindspeed.wpi.edu (Worcester, MA, USA)

• Network– LAN: PCI 10M NIC Win2k professional– Campus uplink: ~50 Mbps (Yipes in 15 Mbps)

• Software– Microsoft Media Player version 7.1– RealNetworks RealOne Player build 6.0.10.505– Ethereal version 0.8.20

November 2002 SIGCOMM Internet Measurement Workshop

1720

1725

1730

1735

1740

1745

1750

1755

1760

30 30.2 30.4 30.6 30.8 31Time (Seconds)

Rea

l P

acke

t N

umber

790

795

800

805

810

815

820

825

830

Med

ia

Pack

et N

umber

Real Play (217K)

Windows Media Player (250K)

IP Packet Arrivals

• RealPlayer – single packets• Media Player – groups of packets (3 in this example)

– 2 at about 1500 bytes (typical MTU)– 1 “left-over” less than MTU

November 2002 SIGCOMM Internet Measurement Workshop

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

0 200 400 600 800

Encoded Bandwidth (Kbits/s)

IP P

acke

ts w

/out

UD

P H

eader

Media Player IP Packet Fragmentation

November 2002 SIGCOMM Internet Measurement Workshop

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0 0.5 1 1.5 2

Normalized Packet size

Prob

abili

ty D

ensi

tyReal Player

Windows Media

Normalized UDP Packet Sizes

Media Player – More “Constant Packet Size”RealPlayer – Less “Constant Packet Size”

November 2002 SIGCOMM Internet Measurement Workshop

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0 0.5 1 1.5 2 2.5 3

Normalized I nterarrival Time I nterval

Cum

ulat

ive

Den

sity

Real PlayerWindow Media Player

UDP Packet Interarrival Times

Media Player – More “Constant Packet Rate”RealPlayer – Less “Constant Packet Rate”

November 2002 SIGCOMM Internet Measurement Workshop

0

100

200

300

400

500

600

700

0 50 100 150 200 250

Time (seconds)

Ban

dwid

th (

Kbit

s/se

c.)Real Player (284K)

Real Player (36K)

Windows Media Player (323K)

Windows Media Player (49K)

Playout Rate

RealPlayer buffers at a higher rate

November 2002 SIGCOMM Internet Measurement Workshop

Frame Rate

5

10

15

20

25

30

35

0 200 400 600 800

Average Bandwidth (Kbits/ sec.)

Fra

me

Rat

e (f

ps)

Real Player

Media Player

RealPlayer significantly higher at low bandwidth

November 2002 SIGCOMM Internet Measurement Workshop

Summary

•Microsoft Media Player typical CBR– Constant packet sizes and interarrivals

•RealNetworks RealPlayer less CBR– Range of packet sizes and interarrivals– Buffers at up to 3 times playout rate

•Media Player has significant IP frag.– 3-5 IP frags / UDP for broadband+ bwidth

•Results can be used for more realistic streaming simulations and emulations

•MediaTracker and RealTracker online:http://perform.wpi.edu/real-tracer/

November 2002 SIGCOMM Internet Measurement Workshop

Future Work

•Build simulated streaming application – In NS

•Server side control– Clip encoding, Content type– (We have server set-up, preliminary

results)

•Bandwidth under congestion– TCP-Friendly?– (We have results for RealPlayer)

•More players and protocols– QuickTime (QuickTracker)

MediaPlayer™ vs. RealPlayer™ A Comparison of

Network TurbulenceMingzhe Li, Mark Claypool, Robert KinickiCS Department

Worcester Polytechnic InstituteWorcester, MA, USA

http://perform.wpi.edu/