mediaplayer vs. realplayer · real packet number 790 795 800 805 810 815 820 825 830 media packet...
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MediaPlayer™ vs. RealPlayer™
A Comparison of Network Turbulence
Mingzhe 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 retransmissions!Chooses UDP
• UDP flows may be unresponsive to congestion!Handle 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 Microsoft
Type Bandwidth (Kbps) (Kbps)1 Sports High 284 323
3:46 Low 36 50 2 Commercial High 268 307
0:39 Low 84 1023 Sports High 284 307
0:60 Low 37 384 Music T.V. High 181 309
4:05 Low 26 505 News High 218 250
1:47 Low 22 396 Movie Clip Very High 637 731
2:27 High 271 347Low 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
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30 30.2 30.4 30.6 30.8 31Time (Seconds)
Real
Pack
et N
umbe
r
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795
800
805
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815
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Med
ia
Pack
et N
umbe
r
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%
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90%
100%
0 200 400 600 800
Encoded Bandwidth (Kbits/s)
IP P
acke
ts w
/out
UDP
Hea
der
Media Player IP Packet Fragmentation
November 2002 SIGCOMM Internet Measurement Workshop
0
0.1
0.2
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0 0.5 1 1.5 2
Normalized Packet size
Prob
ability
Den
sity
Real Player
Windows Media
Normalized UDP Packet Sizes
Media Player – More “Constant Packet Size”RealPlayer – Less “Constant Packet Size”
November 2002 SIGCOMM Internet Measurement Workshop
00.10.20.30.40.50.60.70.80.9
1
0 0.5 1 1.5 2 2.5 3
Normalized Interarrival Time Interval
Cumulat
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
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700
0 50 100 150 200 250
Time (seconds)
Band
widt
h (K
bits
/sec
.)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
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0 200 400 600 800
Average Bandwidth (Kbits/sec.)
Fram
e Ra
te (fp
s)
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 Turbulence
Mingzhe Li, Mark Claypool, Robert KinickiCS Department
Worcester Polytechnic InstituteWorcester, MA, USA
http://perform.wpi.edu/