Dynamic replacement of video coding elements

The long timescale between the development of new technologies for video coding and their adoption into standards results in a slow improvement in compression efficiency despite the scale of ongoing research into new compression techniques. Standards-based codecs have limited capabilities to adapt to changes in video content, delivery environments, or platforms. There is a growing recognition, for example, with the MPEG Reconfigurable Video Coding initiative, that increased codec flexibility is needed. However, we anticipate that even further developments are required to address these stumbling blocks to video coder advancement. To this end, we present a new approach to video coding which enables flexible and dynamic re-configuration of video coding functions. This adaptability is achieved by sending configuration information to the decoder during a communications session as part of the compressed video signal. The decoder responds to this information by reconfiguring itself to adapt the video decoding process as prompted by the encoder. In this paper we describe a particular example of how dynamic re-configuration may be implemented in a simple video coding scenario, namely, a video coder is reconfigured dynamically by sending descriptions of new transforms during coding. We evaluate five approaches to re-configuration and show that all demonstrate rate-distortion gains over baseline coders, despite the rate increase due to sending configuration information.