Performance analysis of a high-performance real-time application with several AL-FEC schemes

Abstract

Abstract-Real-time streaming applications typically require minimizing packet loss and transmission delay so as to keep the best possible playback quality. From this point of view, IP datagram losses (e.g. caused by a congested router, or caused by a short term fading problem with wireless transmissions) have major negative impacts. Although Application Layer Forward Error Correction (AL-FEC) is a useful technique for protecting against packet loss, the playback quality is largely sensitive to the AL-FEC code/codec features and the way they are used. In this work, we consider three FEC schemes for the erasure channel: 2D parity check codes, Reed-Solomon over GF(2 8 ) codes, and LDPCStaircase codes, all of them being currently standardized within IETF. We have integrated these FEC schemes in the FECFRAME framework, a framework that is also being standardized at IETF, and whose goal is to integrate AL-FEC schemes in real-time protocol stacks in a simple and flexible way. Then we modified the Digital Video Transport System (DVTS) high-performance real-time video streaming application so that it can benefit from FECFRAME in order to recover from transmission impairments. We then carried out several performance evaluations in order to identify, for a given loss rate, the optimal configuration in which DVTS performs the best.

Inter-packet symbol approach to Reed-Solomon FEC codes for RTP-multimedia stream protection

“…2), producing n−k redundant packets. In [6], a performance analysis of several FEC schemes, including RS codes, for real time applications is presented. All FEC proposed schemes generate n − k redundant packets from each group of k data packets.…”

“…Therefore it is necessary to specify how the symbols are placed in the information strings. The protection scheme proposed in [6] [8] [9] suggests that each information string is divided into groups of m bits forming RS symbols (see Fig. 2).…”

“…[6]. In this paper, we focus on Reed-Solomon codes since they are particularly appealing for erasure channels and specifically for bursty packets losses, as the case of wireless networks.…”

“…Reed-Solomon codes belong to the class of Maximum Distance Separable (MDS) codes, that is, they offer the best recovery capability for a block code. Nevertheless, their application can be constrained by a remarkable computational complexity in the case that a large size of the Galois Fields is used [4] [6].…”

“…This scheme is based on the well known interleaving technique (e.g. in [5] and [6]) that allows an alternative bit structure that allocates each symbol of the Reed-Solomon code in several RTP-media packets. The novelty consists in applying this technique to Reed-Solomon erasure codes for RTP-media stream.…”