An efficient and scalable low bit-rate video coding with virtual SPIHT

Abstract In this paper, we present a wavelet-based hybrid video coding system with spatial and quality scalability. The proposed video codec is based on 2-D wavelet transform, a modified form of set partitioning in hierarchical trees (SPIHT), called virtual SPIHT (VSPIHT) and temporal motion estimation/compensation. The quantisation and encoding of wavelet coefficients are performed by the colour VSPIHT (CVSPIHT) algorithm. The spatial scalability is achieved by re-organising the bit-stream into layers, one for each spatial resolution. The quality scalability is added through locking the motion compensation loop of the encoder and decoder at a fixed rate. This fixed loop rate is less than or equal to the target bit-rate. The scalability in the standard codec like H.263 is achieved by layered approach and each additional layer requires 20–25% extra overhead, whereas our scalable coder requires less than 1% overhead for spatial scalability and negligible overhead for quality scalability. The simulation results demonstrate that the proposed coder outperforms a layered H.263 codec in terms of both objective and subjective quality.