Media Function

Fraunhofer FOKUS Open Source Media Function

Media Delivery in Managed IPTV Environments

Overview

The FAMElab at Fraunhofer FOKUS has developed a media server component to provide IPTV media function for NGN- and IMS-based IPTV. Conforming to the technical specifications of ETSI TS 182 027, the IPTV media function integrates two layers: a media control function for handling the SIP-based signaling that manages multimedia sessions and a media delivery function for handling media processing and distribution. The media function is fully controlled by its SIP interface, enabling seamless integration in NGN and IMS environments as well as an IPTV service delivery with session control. In addition to the supported services defined in the TISPAN specification—including Broadcast (BC), Video on Demand (VoD) and the connected protocols IGMP, RTSP and RP— the media function has been enriched with additional functionalities allowing smooth and easy integration of User Generated Content (UGC) and mobile devices in the IPTV content distribution system. It provides on-demand media adaptation to accommodate media streams with various network characteristics or end devices. The Fraunhofer FOKUS solution is based on an open SIP stack for signaling and an open source streaming engine for media delivery purposes. Fraunhofer FOKUS has merged these two functions into a single system that enables SIP-based communication for media streaming in next generation media environments. The media function is now available as open source.

Media Delivery in IMS networks

The first question that arises when speaking about media delivery in IMS networks is that there is already a well known entity available namely the Media Resource Function (MRF), which provides services for multimedia conferencing, playing announcements and text-to-speech conversion and acts in this context as a kind of media provisioning entity.
The MRF is subdivided into the Media Resource Control Function (MRCF) as a signaling plane node and the Media Resource Function Processor (MRFP) as a media plane node that implements all media-related functions. Various discussions with partners from the industry and academia showed that the already available approaches for the MRF and its underlying components may be reused for IPTV delivery. According to current TISPAN IPTV definitions the MRF definitions need to be modified or completely new entities need to be introduced. TISPAN defines these entities as the IPTV Media Functions (MF). The MF is in charge of controlling and delivering the media flows to the UE. Closely following the IMS naming guidelines the IPTV Media Function is split into the Media Control Function (MCF) and the Media Delivery Function (MDF).

Solution

Based on the assumptions above and according to TISPAN Draft TS 182 027, we have started to implement a solution that acts as an extended Media Function offering the playout of RTP and RTSP-based IPTV content controlled throughout a SIP interface in the direction of the Open IMS Core incorporating with the Service Control Function (SCF).
The solution is completely written in ANSI C and incorporates open source products for streaming and video handling as well as an open SIP stack for signaling and session handling. These projects have been merged in our project to allow a SIP-based communication for media streaming. The schematic illustration depicts the implemented structure of the a/v streaming functions and the different interfaces to it including the new SIP interface. The Session Manager controls multiple incoming user sessions and merges them in one live content if necessary.

Features

• Representation of TISPAN IPTV Media Functions definitions from Draft ETSI TS 182 027
• SIP-based session setup signaling and incorporation with IPTV Service Control Function
• responsible for Linear TV and IMS-based IPTV playout
• Support for RTP/RTSP based media delivery over unicast and multicast
• Forking and relaying capabilities for flexible in and output selection