Very low bit rate video coding using 3D subband approach
A video coder for very low bit rate applications is designed and simulated. It employs subband analysis technique to first split the video signal into four temporal subbands. Motion detection is performed to classify the co-sited macroblocks of the subbands into temporal activity (TA) macroblocks or no temporal activity (NTA) macroblocks. For the TA macroblocks, motion classification is carried out by further dividing the four temporal subbands into 16 spatiotemporal subbands. The base temporal subband (LL/sub t/) is coded using a H.261-like (European COST 211 ter SIM3) coder with the motion estimation replaced by a reduced-motion search algorithm. The higher temporal subbands (LH/sub t/, HL/sub t/, HH/sub t/) are vector-quantized. The NTA-macroblocks (except in the baseband) are not coded at all. Simulation results are presented at 9.6 kbits per second (kbps) at five frames per second (fps) for a typical videoconferencing sequence. Comparisons are made with results obtained by the SIM3 coder. >