Improvement of error concealment technique for H.264 scalable video coding

Abstract

Today’s scalable video coding technology provides a solution to multimedia content delivery over heterogeneous network to various kinds of terminals. In this thesis, the main focus is on the application of spatial scalability, which enables the delivery of a single multimedia content to users with devices supporting low video resolution to high resolution. However, the ubiquitous delivery network still uses a packet-based approach which cannot necessarily offer a guaranteed Quality of Service (QoS). Some losses may still be corrupt the video bitstream. For a highly compressed H.264 video, a single frame loss may have a dramatic effect on the visual quality of the affected frame as well as its succeeding frames. Error concealment techniques are applied at the decoder side in order to estimate the lost information. Some works on error concealment for the H.264 video coding standard have been presented before, but their performance is found to be inadequate at times. In this thesis, we propose an improved error concealment scheme. We propose a motion estimation method which takes a weighted average of the motion vectors in a neighborhood of macroblocks from the previously decoded frame. Furthermore, the reconstructed frame is enhanced by filtering it with a hybrid median filter. The proposed algorithm was found to have an average gain up to 0.8 dB over the state of the art BL_Skip which was also reflected the better quality in the subjective evaluation. Further investigation also shows that the proposed algorithm is able to suppress the effects of error propagation on the frames succeeding the lost frame.