Analysis of FEC Codes for Partially Reliable Media Broadcasting Schemes

With many multimedia delivery schemes a client does not necessarily receive a given media content entirely (e.g. router congestions can lead some information to be lost). Mechanisms like error concealment and error resilient video coding allow the receiver to deal with partially received data and to play the content, with decreased quality though. Packet-level Forward Error Correction (FEC) can be used as a complementary technique to counter the effects of losses and reconstruct the missing packets. However if the number of packets received is too low for the FEC decoding process to finish, the received parity packets may turn out to be useless, and finally more source packets may be unavailable to the application than if FEC had not been used at all. This paper analyzes the adequacy of the LDGM Staircase, LDGM Triangle and RSE FEC codes to offer a partial reliability service for media content distribution over any kind of packet erasure channel, that is to say a service that enables a receiver to reconstruct parts of the content even if the FEC decoding process has not finished. We analyze this service in the context of a broadcasting system having no feedback channel and that offers media content distribution, like Digital Video/Audio Broadcasting.