An ASBVQ codec for VLBR video coding

A new adaptive subband vector quantisation (ASBVQ) codec for the encoding of video sequences at very low bit rates is presented. The block diagram of the complete system is shown. Overlapped block motion compensation (OBMC) is employed to generate a prediction of the current frame from the previously decoded frame. The OBMC method generates a prediction error signal which can be compressed more efficiently when a subband based coder is used. A 2D discrete wavelet transform is applied to decompose the prediction error frame into 7 subbands. An adaptive subband VQ scheme is employed to quantize the wavelet coefficients and distribute the available bit budget among the subband vector quantizers. For applications where constant bit rate is required this is provided by the adaptive VQ algorithm, eliminating the need for a buffer