TABLE OF CONTENTS In late 1990s the Video Coding Experts Group (VCEG) of the ITU-Telecommunications standardisation sector set up two activities. The aim was to develop very low bit rate video coding at bit rates less than 64 kbit/s and more specifically at less than 24 kbit/s. One activity is looking at the video coding for very low bit rates, under the name of H.263+ [5]. Recently work of this activity has continued under the name of H.263++, indicating further improvements on H.263+ [6]. The other activity, which has more in common with MPEG-4, is work on advanced low bit rate video coding, under the name of H.26L [7].
The H.263+/H.263++ development effort is intended for short term standardisation of enhancements of the H.263 video coding algorithm for real-time telecommunication and related nonconversational services. The H.26L development effort is aimed at identifying new video coding technology beyond the capabilities of enhancements to H.263 by the H.263+/H.263++ coding algorithms.
These two subgroups also have a close cooperation in the development of their codecs, since the core codec is still H.263. They also work closely with the other bodies of ITU. For example, the collaboration between H.263+ and the mobile group has led to consideration for greater video error resilience capability. The back channel error resilience in H.263+ is especially designed to address the needs of mobile video and other such unreliable bit stream transport environments. The H.26L group work very closely with the MPEG-4 group, as this group has the...
