A Cross-Resolution Leaky Prediction Scheme for In-Band Wavelet Video Coding With Spatial Scalability

In most existing in-band wavelet video coding schemes, over-complete wavelet transform is used for the motion-compensated temporal filtering (MCTF) of each spatial subband. It can overcome the shift-variance of critical sampling wavelet transform and improve the coding efficiency of the in-band scheme. However, a dilemma exists in the current implementations of in-band MCTF (IBMCTF), which is whether or not to exploit the spatial highpass subbands in motion compensation of the spatial lowpass subband. The absence of the spatial highpass subbands will result in significant quality loss in the reconstructed full-resolution video, whereas the presence of the spatial highpass subbands may bring serious mismatch error in the decoded low-resolution video since the corresponding highpass subbands may be unavailable at the decoder. In this paper, we first analyze the mismatch error propagation in decoding the low-resolution video. Based on our analysis, we then propose a frame-based cross-resolution leaky prediction scheme for IBMCTF. It can make a good tradeoff between alleviating the low-resolution mismatch and improving the full-resolution coding efficiency. Experimental results show that the proposed scheme can dramatically reduce the mismatch error by 0.3-2.5 dB for low resolution, while the performance loss is marginal for high resolution.