Error Detection and Concealment of Zerotree Wavelet Video Coding

In the zerotree wavelet video coding system, there always exist direct correspondences between the coded symbols. Therefore, if one error occurs in the received bitstream, the rest of decoded data will lose their corresponding relationships and will not be able to reconstruct the original image. From this, we observe that the zerotree coding is very sensitive to transmission errors.
 

In this thesis, we discuss how to improve the performance of the zerotree coding by using the error detection and concealment techniques at the decoding end in error-prone environments. The proposed error detection technology can be categorized into three parts: 1) sequence number code error detection, 2) zerotree mapping error detection, 3) motion vector error detection.
 

The sequence number code error detection adds a sequence number code between an integer number of blocks. Accordingly, we can detect errors by examining the consecutiveness of these sequence number codes. As for the zerotree mapping error detection, it uses zerotree¡¦s coding structure to detect errors through the code correspondence. Furthermore, the motion vector error detection checks the valid range of motion vectors to identify errors. With the above mentioned error detection strategies and the additional error concealment, e.g., the temporal replacement in the wavelet domain, the reconstructed image quality is better than the default H.263 at the error rate above 3e-4.