A method for seamless codec changeover during active video calls

Seamless access to video services in Next Generation Mobile Networks (NGMNs) introduces new challenges in the video quality provisioning. Terminal mobility and network handover affect the Quality of Service (QoS) and the perception of the mobile users. To improve the Quality of Experience (QoE) in NGMNs, cross-layer adaptation of the video streaming is required. A technique to replace the applied video codec during ongoing real-time video transmissions, such as video call, is described in this paper. The presented solution enables to seamlessly switch between the video codecs independently from the applied coding schemes, allows to maintain ongoing sessions, and helps to reduce the changeover-related artifacts to a large degree. The proposed algorithm has been implemented and evaluated in a NGMN testbed. The technique enabled to significantly improve user perception during wireless transmission affected by packet loss, and performed best as compared to network handover and video bit rate reduction that are considered as alternative quality adaptation measures. This proves the relevance of the presented codec changeover solution for video quality provisioning in mobile networks.