Wavelet-based video coder via bit allocation

We present a video coder based on a bit allocation (BA) scheme for a coding approach where a wavelet-based video compression scheme is used to encode a group of frames (GOF). The proposed new BA method utilizes a Lagrangian multiplier technique to determine the optimal bit rate for each frame of a given GOF in a rate versus weighted distortion sense. The proposed baseline coder sequentially employs the application of the wavelet transform on each frame in the group. In the wavelet domain, an optimal-vector BA (rate-allocation strategy) is being used to distribute the bit budget among the frames. The manipulated frames in each group are quantized and coded using techniques from still-image compression. We describe and demonstrate the performance of the proposed algorithm in wavelet-based coding approaches. The first one, a combination of wavelet still compression and optimal BA (WCBA), is based on frame differences and exploits well the wavelet compression characteristics which keeps, for a given bit budget, the most important features. It does not utilize motion-compensation interpolation or a 3-D wavelet decomposition. In cases where "heavy" motion is detected, we extend WCBA into a combination of wavelet still compression, optimal BA, motion compensation with block matching, and error correction (WCBAM), which uses block matching for motion estimation, while the residual error of the compression is reduced by applying error correction in the wavelet domain to reduce temporal redundancies.