On Sun, Nov 24, 2019 at 07:35:47PM +0600, Sujit Roy wrote:

How can i change c= and o= in SDP using RTPProxy ?

You must have read over it in the documentation: https://www.kamailio.org/docs/modules/stable/modules/rtpproxy.html#rtpproxy....

Thus by using the c and/or o flags your question might be answered.

If you need a complete example searching for "kamailio rtpproxy example config" found this for me: https://github.com/sipwise/kamailio/blob/master/etc/kamailio.cfg (and many more).