A Block-Based SNR Scalable Wavelet Video Codec with Sub-pixel Motion Vectors and R-D Optimization

We propose a block-based wavelet codec in which motion vector estimation and motion residual encoding are performed within a wavelet domain. By interpolation on dyadic wavelet transform, we show that motion vector estimation in the wavelet domain can achieve sub-pixel precision. To improve PSNR performance at low bit rates, we propose a bit-plane-based rate-distortion (R-D) optimization algorithm. This algorithm allocates an optimal number of bit-planes to each macroblock. Our codec is SNR scalable and our bit-stream syntax is fully compatible with that of H.263. Experiments show that our block-based wavelet codec outperforms a framebased wavelet codec. Also, compared with H.263 baseline results, our wavelet codec is competitive at low bit rates, and is superior at higher bit rates.