/mcpVideo Calls The typical video call includes two or three Real-Time Protocol (RTP) streams in each direction (that is, four or six streams). The call can include the following stream types: • Video (H.261, H.263, H.263+, H.264-SVC, X-H.264UC, H.264-AVC, H.265, AV1 and VT Camera wideband video codecs) • Far-End Camera Control (FECC) - Optional • Binary Floor Control Protocols (BFCP) Call control for video calls operates the same way as the call control that governs all other calls. For more information, see the Configure Media Resources chapter in the System Configuration Guide. You can also see, Configure Conference Bridges chapter in the System Configuration Guide for details on how Unified Communications Manager can allocate a video conference bridge automatically. Note Real-Time Transport Control Protocol Pass-Through in MTP Topologies An IOS Media Terminate Point (MTP) before 15.2(2)T, cannot pass-through Real-Time Transport Control Protocol (RTCP) packets and therefore cannot exchange Real-Time Protocol (RTP) feedback data to enhance the RTP transmission. The primary function of RTCP is to provide feedback on media distribution by periodically sending statistics to participants in a streaming multimedia session. RTCP gathers statistics for a media connection and information such as transmitted octet and packet counts, lost packet counts, jitter, and round-trip delay time. An application may use this information to control the quality of service parameters, perhaps by limiting flow or using a different codec. IOS MTP Version 15.2(2)T and later supports RTCP pass-through capability so that the endpoint in a call with an MTP present can still provide feedback and status on an RTP transmission. RTCP pass-through capability applies to media channels. The RTCP pass-through feature is not limited to a specific call signaling protocol. For example, it can be SIP-SIP, SIP-nonSIP, or nonSIP-nonSIP. For Unified CM to allocate an RTCP pass-through capable MTP specifically, the call needs to fulfill the following conditions: • An MTP is requested for a feature that requires the MTP to be in media pass-through mode. For example, TRP, DTMF translation, IP address V4/V6 translation, and so on. RTCP pass-through is only applicable when the media is in pass-through mode. • The RTCP pass-through MTP needs to be included in the Media Resource Group Lists (MRGL) of the endpoint that sponsors the MTP. MTP can be inserted by RSVP, TRP, DTMF mismatch reasons. • When the call is capable of establishing video channels, Unified CM attempts to search for an RTCP pass-through capable MTP. For example, Unified CM picks an RTCP pass-through capable MTP from other non-capable ones in the MRGL. If an RTCP pass-through capable MTP is not available, then Unified CM stills allocate an MTP for the call. • When the call is capable of establishing an audio channel only, Unified CM does not intentionally request an RTCPpass-through capable MTP for the non-video calls. However, if the MRGL only contains RTCPpass-through capable MTP(s), then Unified CM inserts one of those into the audio call. Feature Configuration Guide for Cisco Unified Communications Manager, Release 15 and SUs 860 SIP Interoperability Video Calls