Multimedia resource function controller
The multimedia resource function controller (MRFC) and the multimedia resource function processor (MRFP) handle the bearer-related services. Recall that the bearer channel is the media pipeline in the IMS. The MRFC and the MRFP are deployed in logical pairs and provide bearer functions for sessions. The MRFC acts as an interpreter in the user plane while the MRFP performs the actual operations.
The MRFC controls such things as conferencing, announcements to a user, or bearer transcoding. As an aside, transcoding is the term that defines the conversion from one form of codec to another. For example, transcoding could be from Beta to VHS or from a PC display to a much smaller cell phone display. The MRFC receives the SIP signaling from the S-CSCF and uses the Media Gateway Control Protocol (MEGACO) instructions to control the MRFP. As is usually the case, the MRFC is able to send accounting information to the CCF and OCS.
The MRFP does all of the work on the user-plane and provides the resources that are requested by the MEGACO instructions, which were issued by the MRFC. Some of these functions are listed below.
- Mixing of the incoming media streams that multiple parties would have created as part of a conferencing service.
- Sourcing of the media stream that would be used as an announcement message for a user. The tone that sounds at the start of an instant message (IM) is an example of an announcement message that could come from the MRFP. The MRFP also sends along the stream if some processing is required.
- Processing of the media stream where some transcoding function would be required. Using the IM example again, the transcoding function may be required to change the IM from a PC form to a cell phone form, or perhaps from text to verbal presentation.