一种自适应冗余字典和自适应正交DCT基的两级视频编码框架
A two-stage video coding framework with both self-adaptive redundant dictionary and adaptively orthonormalized DCT basis
摘要：
在这项工作中，我们提出了一个两阶段的视频编码框架，作为我们以前的一个阶段的框架在[1]中的扩展。两阶段框架由两个不同的字典组成。具体地说，第一阶段直接找到一个自适应字典组成的所有可能的帧间预测候选块的稀疏表示，通过解决一个L0范数最小化问题，使用改进的正交匹配追踪与嵌入式正交归一化（eOMP）算法，和第二阶段编码的残差使用DCT字典自适应正交归一化到第一阶段原子所跨越的子空间。第一级和第二级的转换基于两级的量化步长和阈值来确定。我们进一步提出了一个完整的上下文自适应熵编码器，有效地编码的位置和选定的第一级原子的系数。仿真结果表明，该编码器显着提高了RD性能比我们以前的一级编码器。更重要的是，仅使用固定块大小和帧间预测的两阶段编码器优于H. 264编码器（x264），并且在大速率范围上与HEVC参考编码器（HM）竞争。
英文摘要：
In this work, we propose a two-stage video coding framework, as an extension of our previous one-stage framework in [1]. The two-stage frameworks consists two different dictionaries. Specifically, the first stage directly finds the sparse representation of a block with a self-adaptive dictionary consisting of all possible inter-prediction candidates by solving an L0-norm minimization problem using an improved orthogonal matching pursuit with embedded orthonormalization (eOMP) algorithm, and the second stage codes the residual using DCT dictionary adaptively orthonormalized to the subspace spanned by the first stage atoms. The transition of the first stage and the second stage is determined based on both stages' quantization stepsizes and a threshold. We further propose a complete context adaptive entropy coder to efficiently code the locations and the coefficients of chosen first stage atoms. Simulation results show that the proposed coder significantly improves the RD performance over our previous one-stage coder. More importantly, the two-stage coder, using a fixed block size and inter-prediction only, outperforms the H.264 coder (x264) and is competitive with the HEVC reference coder (HM) over a large rate range.
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