Network Syst. Div., Adv. Technol. Res. Center, Mount Prospect, IL.
IEEE Trans Image Process. 1997;6(11):1487-502. doi: 10.1109/83.641410.
We present a theory for the optimal bit allocation among quadtree (QT) segmentation, displacement vector field (DVF), and displaced frame difference (DFD). The theory is applicable to variable block size motion-compensated video coders (VBSMCVC), where the variable block sizes are encoded using the QT structure, the DVF is encoded by first-order differential pulse code modulation (DPCM), the DFD is encoded by a block-based scheme, and an additive distortion measure is employed. We derive an optimal scanning path for a QT that is based on a Hilbert curve. We consider the case of a lossless VBSMCVC first, for which we develop the optimal bit allocation algorithm using dynamic programming (DP). We then consider a lossy VBSMCVC, for which we use Lagrangian relaxation, and show how an iterative scheme, which employs the DP-based solution, can be used to find the optimal solution. We finally present a VBSMCVC, which is based on the proposed theory, which employs a DCT-based DFD encoding scheme. We compare the proposed coder with H.263. The results show that it outperforms H.263 significantly in the rate distortion sense, as well as in the subjective sense.
我们提出了一种用于四叉树（QT）分割、位移向量场（DVF）和位移帧差（DFD）之间最优比特分配的理论。该理论适用于可变块大小运动补偿视频编码器（VBSMCVC），其中使用 QT 结构对可变块大小进行编码，使用一阶差分脉冲编码调制（DPCM）对 DVF 进行编码，使用基于块的方案对 DFD 进行编码，并采用附加失真度量。我们基于 Hilbert 曲线推导出了一种 QT 的最优扫描路径。我们首先考虑无损 VBSMCVC 的情况，为此我们使用动态规划（DP）开发了最优比特分配算法。然后，我们考虑了一种有损 VBSMCVC，对于这种情况，我们使用拉格朗日松弛，并展示了如何使用基于 DP 的解决方案的迭代方案来找到最优解决方案。最后，我们提出了一种基于所提出的理论的 VBSMCVC，它采用基于 DCT 的 DFD 编码方案。我们将所提出的编码器与 H.263 进行了比较。结果表明，它在率失真意义上以及主观意义上都明显优于 H.263。
