User perceived codec and duplex aware playout algorithms and LMOS-DMOS measurement for real time streams

In the network devices for real time streaming, e.g. VoIP phone, video phone and online game, the playout algorithm controls the playout delay to eliminate the jitter and to minimize the overflow packet loss. Conventional algorithms did this based on network delay only; they did not consider the user perceived quality, and aware the codec and communication duplex mode. Therefore, we present two novel approaches: codec aware adaptive playout (CAAP) and duplex aware adaptive playout (DAAP), they intend to optimize the user perceived quality based on codec and communication duplex mode respectively. Because of their different characteristics, CAAP and DAAP can work either alone or together; and their improvements are accumulative. The out-performance of CAAP and DAAP are superior the prior algorithm in our substantial but conservative evaluation. Since no objective mechanisms for measuring the speech quality of two-way communication exist; a new LMOS-DMOS measurement mechanism is also proposed. Although VoIP is an exemplary embodiment in this paper, we formally model our algorithms into a generalized user perceived QoS control as well.