motion estimation and compensation for very low bitrate video coding

Conclusion
With the emergence on the market of low-cost cards allowing customers
to decode the ISO MPEG-1 and MPEG-2 standards, digital video coding
is becoming a very common functionality ofmultimedia personal
computers. For several years, video coding has moved towards verylow
bitrates (under 64kbits=s). A major result of this trend is the ITU
H.263 standard which also has the advantage that the software version
of its decoder performs in real-time on a PC. The future ISO MPEG-4
standard goes one step further as it o ers the possibility to the user to
somehowinteract with the contents of the pictured scene. Because of the
convergence of the target bitrates with the ever-increasing capabilities of
existing networks, some people already claim that these two standards
are putting an end to research in \pure" video coding.
Among the tools used to achieve compression of the video signal, motion
estimation is probably the one o ering the greatest compression ratio. A
lot of research has been devoted to it during the last two decades. It not
only resulted in great outcomes in video coding but also in other elds
where motion analysis plays a key role, like semantic interpretation or
target tracking. The exploitation of motion in a video coding scheme
typically involves three steps: estimation, transmission and compensation.
The video coding context and the state of the art in related motion
estimation techniques have respectively been presented in Chapter One
and Chapter Two. Some emphasis was put on the very-low bitrate
environment and on the most used motion estimation techniques (BMA
and warping techniques). In this sense, the present thesis contributes to
the investigation of the possibility to enhance the various steps of the
motion chain by somehow taking into account the spatial contents of the
image(s).
Chapter Three modi es the estimation performed by a classical BMA