EFFECTS OF LOCALITY, CONTENT AND JAVA RUNTIME ON VIDEO PERFORMANCE Vikram Chhabra, Akshay Kothare, Mark Claypool Computer Science Department Worcester Polytechnic Institute Worcester, Massachusetts, USA

Introduction Increased bandwidth has enabled video streaming to the desktop. Java’s “Write once, run anywhere” - preferred choice for multimedia applications.

Java Runtime Java Source Bytecode JVM Native OS JIT Compiler C++ Source

Java Performance Java lags the speed of C / C++. Need to explore factors influencing the performance of Java.

Performance of Multimedia Frame Rate : Numbers of frames displayed per second. Jitter : Variance in time taken for a frame to travel from server to client.

Previous Work Most performance evaluations have been for traditional media. Our previous work suggests: –Local access of media –Processing power of the native hardware mostly influence the performance of Java.

Our Approach Setup a controlled environment Serve movie to Java client Observe frame arrival time Calculate frame rate & jitter Derive conclusions

Experimental Setup C++ ServerJava Client TCP/IP No frame loss Hard Disk

Parameters to be tested Network distance Movie content JIT compilation

Parameter One : Network Distance Four Setups: 1.Local Playback 2.Dedicated Client/Server 3.Normal Setup 4.Different Switch Fixed Parameters : Operating System : Linux 6.3 kernel version Server : Pentium MMX 233 MHz PC with 64MB of RAM. Client : Pentium II 300 MHz PC with 128MB of RAM. Network : Ethernet broadband coaxial cable at 10Mbps. Movie : A space scene, encoded as 120 “ I ” frames

Parameter Two : Movie Content Ten “ perceptually different ” movies –fixed resolution of 200 x 200 pixels –120 frames each, 4 seconds each –“I” and “IBBPBBPBBPBB” group of pictures format. I Frame : Fully Encoded B or P Frames : Relatively Encoded Fixed Parameters : Client : WinNT 4.0 service pack 6 (Pentium MMX 233 MHz, 64MB RAM) Server : SuSE Linux 6.4 Kernel version (Intel PIII 500Mhz PC, 128 MB RAM) Network : 100 Mbps Ethernet

The Movies

Parameter Three : JIT Compilation JIT “on” vs. “off” “Java” vs. “C” Fixed Parameters : Operating System : Linux 6.3 kernel version Client : Pentium II 300 MHz PC with 128MB of RAM. Movie : A space scene, encoded as 120 “ I ” frames

RESULTS

Network Distance – Frame Rate “ Local media access faster than different network setups ”

Network Distance – Jitter “ Local media access shows lesser jitter than network access ”

Movie Content – Frame Rate “ Movie content affects the frame rate ”

Movie Content – Jitter “ Movie content affects jitter ”

JIT Compilation – Frame Rate “ JIT enhances performance, Java still lags power of C ”

JIT Compilation – Jitter “ JIT reduces jitter ”

Conclusions Local media access faster than network –5% higher frame rate, 25% lesser jitter Not much difference over different networks Movie content has significant implications –Blue movie 3 times faster and shows 40% lesser jitter than Mixbag

Conclusions (contd.) JIT gives performance boost –100 % increase in frame rate –25% decrease in jitter Java still lags C –Java (JIT on) frame rate 10 times less than C

Future Work Trying different protocols –UDP, RMI, CORBA instead of TCP. Finding relationship between decrease in frame rate with perceptually different movie content. Trying different JVMs and/or JITs.