| With the fast development of network and multimedia techniques, multimedia has been required in a growing number of application environments and scenes. As state-of-the-art video coding standard, H.264/AVC defines a number of profiles for different applications, including the H.264/AVC Baseline Profile. In the H.264/AVC Baseline Profile, bi-predictive (B) slices are not supported, which results in a decreased coding efficiency compared with other profiles supporting B slices. However, many application standards, such as the mobile multimedia services specified by the Third Generation Partnership Project (3GPP), use only the H.264/AVC Baseline profile. Therefore, it is worth investigating the coding efficiency of the H.264/AVC Baseline Profile in the case that only I (intra) and P (inter) slices are supported.Based on the H.264/AVC standard and its extension Scalable Video Coding (SVC), the thesis analyzes the temporal hierarchical video coding structure and investigates the corresponding quantization techniques in hierarchical structure theoretically and practically, for the purpose of improving the coding efficiency. The main contents and novelties of this thesis are as follows:1. This thesis proposes a new hierarchical video coding structure for the H.264/AVC Baseline Profile.B slices and CABAC (Context-based Adaptive Binary Arithmetic Coding) entropy coding are not supported in the H.264/AVC Baseline Profile and these lead to a lower coding efficiency compared with other profiles. After the investigation of the mostly used Hierarchical B coding structure in other profiles of H.264/AVC and SVC, the thesis proposes a new Hierarchical P coding structure for the H.264/AVC Baseline Profile, which is similar to Hierarchical B coding structure, with its own properties. The proposed structure can greatly improve the coding efficiency of the H.264/AVC Baseline Profile.2. This thesis proposes a novel content-adaptive QP cascading mechanism for hierarchical coding structure.This thesis investigates some approaches of QP (Quantization Parameter) setting mechanisms in Hierarchical B coding structure and analyzes the advantages and disadvantages of them. Then a novel content-adaptive picture-level QP cascading mechanism is proposed. It should be noted that this mechanism is not only appropriate for Hierarchical P structure but also for Hierarchical B structure.Experimental results show that, compared with traditional"IPPP…"coding structure, the proposed Hierarchical P coding has a greatly better rate-distortion performance; Meanwhile, the proposed QP setting mechanism also shows a significant improvement of rate-distortion performance at the cost of slightly more computational complexity. |
