Low bit rate audio-visual communication having improved face and lip

Abstract

Disclosed is a low bit rate audio and video communication system which employs an integrated encoding system that dynamically allocates available bits among the audio and video information and the manner in which the audio and video information will be perceived by a viewer. A dynamic bit allocation and encoding process will evaluate the current content of the audio and video information and allocate the available bits among the audio and video signals to be encoded based upon the perceptual significance of that information. A face location detection subroutine will detect and model the location of faces in each video frame, in order that the facial regions may be more accurately encoded than other portions of the video frame. A lip motion detection subroutine will detect the location and movement of the lips of a person present in a video scene, in order to determine when a person is speaking and to encode the lip and face regions more accurately. By way of example, the face region may be modelled as a first ellipse and the lip region may be modelled as a second smaller ellipse contained within the first ellipse.