Content based very low bit rate video coding using wavelet transform

In this paper we present a new hybrid compression scheme for videoconferencing and videotelephony applications at very low bit rates (i.e., 32 kbits/s). In these applications, human face is the most important region within a frame and should be coded with high fidelity. To preserve perceptually important information at low bit rates, such as face regions, skin-tone is used to detect and adaptively quantize these regions. Novel features of this coder are the use of overlapping block motion compensation in combination with discrete wavelet transform, followed by zerotree entropy coding with new scanning procedure of wavelet blocks such that the rest of the H.263 framework can be used. At the same total bit-rate, coarser quantization of the background enables the face region to be quantized finely and coded with higher quality. The simulation results demonstrates comparable objective and superior subjective performance when compared with H.263 video coding standard, while providing the advanced feature like scalability functionalities.