This paper introduces a rate-adaptive FireFort-LDGM (FF-LDGM) code for MMT adaptive Application Layer FEC (AL-FEC). The FF-LDGM code is an ISO/IEC MPEG international standard issued in Feb. 2015. It can handle a wade range of block lengths from a small number of packets to several thousands of packets. Especially, it is useful for real-time UHD video transmission. In this paper, we focus on recent advances in the rate adaptive FF-LDGM code. It provides a rate adaptive function that allows the coding rate to be adaptively changed to suit the network characteristic. We improve the error recovery performance of the rate-adaptive scheme by using selective interleaving. Simulation results demonstrate its superior adaptive performance.