[ns] What is the file format of tracefile in [new Application/Traffic/Trace]?

[Prathap M]

Hi Ns-users,
                 I am doing project in video streaming in Wired-cum-wireless
network. I am having a trace file of "video.dat".  I had attached the
tracefile to traceobject[ instance of new Application/Traffice/Trace] , But
while executing

"
set video [new Application/Traffic/Trace]
$video attach-tracefile $trace-filename
$video start
"

ns is giving error as

"
bad file size in video.dat
segmentation fault
"

I dont know the reason of the error. If any one  knows the solution kindly
give me the solution . or if any one have  the sample piece of the code  it
will be a great help to me. Waiting for your replies....

Regards,
Prathap.M