Spatio-temporal error concealment techniques in scalable video coding: Master's Thesis

Modern technology has made it possible to transfer real-time video to various mobile terminals in wireless networks. The same video can be streamed to low bit rate mobile phones with low quality as well as high bit rate televisions with extremely high quality. Scalable video coding has enabled adaptive video transmission, where several types of sub-streams can be decoded from a single encoded stream with the desired spatial, temporal and quality characteristics that are suitable for the specific applications. However, the wireless transmission environment is very error-prone compared to the wired systems. A propagation channel can cause bit inversions and the network load can eventually lead to packet losses. Since the strict real-time requirements usually rule out the possibility of re-transmission, the transmission errors can result in a situation where parts of a video stream are missing, which in turn can lead to poor video quality. This means that error protection and concealment techniques are needed. This master’s thesis studies the spatio-temporal error concealment techniques in scalable video coding focusing on the error resilience in the scalable video extension of the H.264/AVC video coding standard. A new error concealment technique is developed in this work, which utilises the correctly received spatial enhancement layer information if the corresponding base layer is missing. The purpose of this research is to study whether this new technique is worth using rather than the traditional techniques that were also implemented in this work. Unlike the new method, the traditional methods discard the corresponding enhancement layer data in the case when the base layer is missing. In addition, an extensive simulation environment was set up in order to compare these different methods. The simulation results indicate that enhancement layer utilisation provides better results in the case of a missing base layer than the traditional error concealment methods. It can also be seen that the new error concealment technique is suitable for video sequences containing both plenty of motion and a relatively static background.