Very low bit-rate video coding using wavelet-based techniques

In this paper, we propose a very low bit-rate video coding scheme based on a discrete wavelet transform (DWT), block-matching motion estimation (BME), and overlapped block motion compensation (OBMC). Our approach reveals that the coding process works more efficiently if the quantized wavelet coefficients are preprocessed by a mechanism exploiting the redundancies in the wavelet subband structure. Thus, we introduce a new framework of preceding techniques based on the concepts of partitioning, aggregation, and conditional coding (PACC). Our experimental results show that our PACC coder outperforms the VM (Version 5.1) of MPEG4 both for the coding of intraframes (1-2 dB PSNR) and residual frames (up to 1.5 dB PSNR) of typical MPEG4 test sequences. The subjective quality of reconstructed video is, in general, superior to that obtained from the VM implementation. In addition, when restricted to the intraframe mode, the proposed coding algorithm produces results which are among the best reported for still image compression.