Low bit-rate video coding via mode-dependent adaptive regression for wireless visual communications
In this paper, a practical video coding scheme is developed to realize state-of-the-art video coding efficiency with lower encoder complexity at low bit-rate, while supporting standard compliance and error resilience. Such an architecture is particularly attractive for wireless visual communications. At the encoder, multiple descriptions of a video sequence are generated in the spatio-temporal domain by temporal multiplexing and spatial adaptive downsampling. The resulting side descriptions are interleaved with each other in temporal domain, and still with conventional square sample grids in spatial domain. As such, each side description can be compressed without any change to existing video coding standards. At the decoder, each side description is first decompressed, and then reconstructed to original resolution with the help of the other side description. In this procedure, the decoder recover the original video sequence in a constrained least squares regression process, using 2D or 3D piecewise autoregressive model according to different prediction modes. In this way, the spatial and temporal correlation is sufficiently explored to achieve superior quality. Experiment results demonstrate the proposed video coding scheme outperforms H.264 in rate-distortion performance at low bit-rates and achieves superior visual quality at medium bit-rates as well.