Three-dimensional subband coding techniques for wireless video communications

We present a new 3D subband coding framework that achieves a good balance between high compression performance and channel error resilience. Various data transform methods for video decorrelation were examined and compared. The coding stage of the algorithm is based on a generalized adaptive quantization framework which is applied to the 3D transformed coefficients. It features a simple coding structure based on quadtree coding and lattice vector quantization. In typical applications, good performance at high compression ratios is obtained, often without entropy coding. Because temporal decorrelation is absorbed by the transform, traditional motion compensated prediction becomes unnecessary, resulting in a significant computational advantage over standard video coders. Error-resilience is achieved through classifying the compressed data streams into separated sub-streams with different error sensitivity levels. This enables a good adaptation to different channel models according to their noise statistics and error-protection protocols. Experimental results have shown that the subband video coder is able to achieve highly competitive performance relative to MPEG-2 in both noiseless and noisy environments. Lapped transforms are shown experimentally to outperform other transforms in the 3D subband environment. The subband coding framework provides a practical solution for video communications over wireless channels, where efficiency, error resilience and computational simplicity are vital in providing superior quality of service.