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<concept id="GUID-7D1E2DBD-004B-5047-BDA5-21CD55D0A95C" xml:lang="en"><title>Securing

RTP with SRTP</title><shortdesc>This topic explains how to use callbacks to secure RTP communications. </shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody>

<p>If you have registered preprocessing and postprocessing callbacks, the

RTP stack calls them when sending or receiving RTP data. Therefore, your application

can implement Secure RTP by adding encryption and authentication steps after

reception and before sending. </p>

<p>Your callback class must derive from MPrePostProcessingCallback and implement

its four methods. Call the <xref href="GUID-97FC8566-E4AD-3881-8669-134798A88779.dita"><apiname>SetPrePostProcessingRegisterCallback(</apiname></xref> method

to register your callbacks. After registration, the callback behaviour is

as follows: </p>

<ul>

<li id="GUID-EC65A889-9113-5095-9E15-42C91E76327B"><p>The RTP stack calls

the appropriate preprocessing callback, <xref href="GUID-97FC8566-E4AD-3881-8669-134798A88779.dita"><apiname>PreRtpProcessing()</apiname></xref> or <xref href="GUID-97FC8566-E4AD-3881-8669-134798A88779.dita"><apiname>PreRtcpProcessing()</apiname></xref>, after data is received

from the socket and before processing RTP headers. </p> </li>

<li id="GUID-B78CDB23-D742-5B70-9F61-0712873EE3B3"><p>The RTP stack calls

the appropriate postprocessing callback, <xref href="GUID-97FC8566-E4AD-3881-8669-134798A88779.dita"><apiname>PostRtpProcessing()</apiname></xref> or <xref href="GUID-97FC8566-E4AD-3881-8669-134798A88779.dita"><apiname>PostRtcpProcessing()</apiname></xref> , after completing an

RTP or RTCP packet and before sending it to the socket. </p> </li>

</ul>

</conbody><related-links>

<link href="GUID-993629CB-17B4-5E87-8DE1-06A4AC473FDD.dita"><linktext>RTP Overview</linktext>

</link>

</related-links></concept>