Source Description (SDES) items are normally transported in RTP control protocol (RTCP). In some cases it can be beneficial to speed up the delivery of these items. Mainly when a new source (SSRC) joins an RTP session and the receivers needs this source's identity, relation to other sources, or its synchronization context, all of which may be fully or partially identified using SDES items. To enable this optimization, this document specifies a new RTP header extension that can carry SDES items.