針對可調視訊編碼粗略可調性之模式相依的位元與失真解析模型

Abstract

可調視訊編碼的層間預測和動作補償預測中執行動作預測的區塊其不同的分割模式會導致位元與失真上差異。然而現今只有少數模型可以解釋可調式視訊編碼位元與失真行為，更遑論有任何方法可以讓我們針對可調視訊編碼中不同的區塊分割模式分析其位元與失真關係。針對可調視訊編碼粗略可調性，本論文推導出了一個解析性及模式相依的位元與失真關係模型。考慮到加強層為可採用層間殘留預測的壓縮方式，我們對可調視訊編碼中基礎層與加強層各提供了一取決於區塊分割模式和影像特性的位元與失真模型。在我們所提出的位元與失真模型推演過程中採納了一個向前信道模型以及一個時間上穩態的過程假設，我們藉由一個動作預測軌跡詮釋重建區塊，並且將殘留變異數設計成一個統計量模型。實驗結果顯示，我們提出的模型可以很準確的估量出不同區塊分割模式，其真實壓縮出的基礎層及加強層的位元與失真曲線。並且最後針對不同區塊分割層間殘留預測的效能分析後，所提出的模型也呈現與真時壓縮相似的位元與失真趨勢。

In Scalable Video Coding (SVC), the inter-layer prediction and the variable motion estimation block partition modes for motion-compensated prediction (MCP) cause differences in rate and distortion behavior; however, there are just few models could explain the rate and distortion behavior of SVC, not to mention methods which focus on analyzing the rate and distortion of different partition mode pairs in SVC. In this thesis, we derive analytical mode-dependent rate and distortion models for Coarse-grain scalable video coding techniques. The rate and distortion models for base and enhancement layer both depend on the partition mode and sequence characteristics with consideration of the inter-layer residual prediction capability in enhancement layer. Adopting a forward channel model and an assumption of temporal-stationary process in the derivation of proposed models, we interpret the reconstructed block by a motion prediction trajectory and model the transformed residual variance into a mode-dependent statistic. Our experimental results show that the proposed model can estimate the actual-coded R-D curves of different partition modes in base layer and enhancement layer with high accuracy. In addition, similar tendencies between model and actual-coded curve are observed over the performances of different mode pair encoded with inter-layer residual prediction.