A dynamic video combiner for multipoint video conferencing using wavelet transform

A new architecture of video combiner for multipoint video conferencing is proposed. The proposed video combiner is wavelet-based which extracts the motion activities information from the video bitstreams produced by a wavelet-based video coder. Using the progressive properties of wavelet transform, the encoded bitstream become scalable. Hence, the video quality of inactive sub-sequences can be easily adjusted in the video combiner by discarding the fine detail information bitstreams. In other words, more bits can be reallocated to the active sub-sequences to achieve a good visual quality with smooth motion. In addition, the video coder is region-based so that different wavelet kernels can be used for the foreground and the background. This setting can on one hand reduce the computational complexity significantly. On the other hand, by considering the unequal importance of various regions, a high video quality in foreground can always be guaranteed and an acceptable quality in background can be maintained even under low bitrate environments. Since the video combiner only needs to rearrange the video quality level according to their motion activities, no re-encoding process is required. Therefore, a significant computational complexity saving can be achieved as compared to the conventional video combiner using a transcoding approach. The new video combiner is then used to realize a multipoint video conferencing and some results are presented to show the improvement in performance due to our proposed architecture.