Error robustness improvement of video codecs with two-way decodable codes

Abstract

Owing to the variable rate nature of compressed video bit streams, a single error may cause loss of synchronisation which results in false decoding. Therefore, when the decoder detects an error, it usually skips all the bits until the next synchronisation word. In this case, the correct bits located between the corrupted bit and the synchronisation word cannot be decoded without using two-way decodable codes which permit reverse decoding of the bit stream. The authors explain the two-way decoding concept and use it to modify the ITU H.263 video coding algorithm in order to improve its robustness against channel errors.