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# Points for havman56

http://www.experts-exchange.com/jsp/qManageQuestion.jsp?ta=cplusprog&qid=20284244

Hi havman56,

Thank for helping . I have a other 500 points-question for you . I need source code calculate the latency of array of rtp packets .

Note :

1. The array of packets can  have some lost packets .

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thienpnguyen
• 6
1 Solution

Commented:
Thienpnguyen

nice to get a question pointed on me.

sure i will do for u with pleasure. i dont have any code as of now.i ned to write it!

but i have coded for RTP before 1 year. i will recollect it and i will do the needful for me.

apart from this serah the web

there is a library available for RTP from lucent website.
u can use it !it works fine...

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Author Commented:
Thank for reply as soon as posible .

When you have the source code, please post it at here . I will make some "dummy" questions to give points to you .

Sincerely,
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Commented:
sure

i will post it! when is finished writing RTP code
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Commented:
thienpnguyen

i am working on it!

may be after 2 days i will post here!
This is to inform u that i have not forgoted ur queery...
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Commented:
/*****************************************************************
Author          : Mangal Dass P
Date          : 23rd may 2000
Description : This gives the inter arrival jitter of RTP packets

Description     :  An estimate of the statistical variance of the RTP data packet
interarrival time, measured in timestamp units and expressed as
an unsigned integer. The interarrival jitter J is defined to be
the mean deviation (smoothed absolute value) of the difference D
in packet spacing at the receiver compared to the sender for a
pair of packets. As shown in the equation below, this is
equivalent to the difference in the "relative transit time" for
the two packets; the relative transit time is the difference
between a packet's RTP timestamp and the receiver's clock at the
time of arrival, measured in the same units.
Environment : MS VCcompiler

not tested needs more improvement. initial version without timing behaviour

Email          : micro_mangal@yahoo.com

****************************************************************************************/

#include "rtp.h"

RTP_PACKET  s[2],r[2];

int arrival=150;
main()
{

int transit;
int d;
int i;

/*
* Initialsiing the values of timestamp but the
* real time operation is not considered here purely
* aribitarly values in ms. the values may be wrong too.
*/

s[0].ts=100;
s[1].ts=150;
r[0].ts=125;
r[1].ts=175;
s[0].transit=0;
s[0].jitter=0;

/*
* assume there are 3 packets both in sender and reciver
*/
for(i=0;i<=2;i++)
{

/* arrival is  defined as the time at which packet
* reaches the destination.
* reciver Time stamp is defined as the time at which
* clock of reciver places the value at the packet
*/

transit = arrival - r[i].ts;

/*
* d is teh delay between transit delay and the initial time stamp of the sender
*/
d= transit- s[i].transit;

/*
*  for the next iteration ie fro next packet
*/
s[i+1].transit=transit;

/*
* jitter is calculated by using the formula here.
*/

s[i+1].jitter += (1./16.) * ((double)d - s[i].jitter);

arrival= arrival + d;

}

}

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Commented:
still not completed.. yet to be solved ...

typedef struct _RTP_PACKET
{

unsigned short int ts;               /* timestamp */
unsigned short int transit;
float jitter;
} RTP_PACKET;
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Commented:
i need ur input before proceeding...

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