Design and Implementation of H.264/MPEG4-AVC Scalable Extension Encoder on Multi-Core Processors
| Autor: | Shu-Sian Yang, 楊恕先 |
|---|---|
| Rok vydání: | 2007 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 95 Scalable Video Coding (SVC) is designed for multimedia systems which require video of various spatial and temporal resolutions to be transmitted or stored. In addition to the Fine Grain Scalability (FGS), SVC provides the capability of reconstructing reduced spatial and/or temporal resolution video by simply discarding unnecessary part of the bit-stream from the complete one. After the debut of the latest single layer video coding standard, H.264/MPEG4-AVC, the Joint Video Team of the ISO/IEC Moving Picture Experts Group and the ITU-T Video Coding Experts Group invests a great deal of effort in the Scalable Extension of H.264/MPEG4-AVC. Most components of H.264/MPEG4-AVC are adopted in current SVC design to allow the base layer of an SVC bit-stream can be decoded by any H.264/MPEG4-AVC conforming decoder. The tradeoff between scalability and coding efficiency is also well-compromised. The PSNR degradation is controlled within 1 dB in average. Although SVC provides good coding performance and scalabilities, the additional flexibility also brings high computation complexity which limits application scenarios. To accelerate the encoder, we exploit the characteristics of the layered coding structure of SVC. We propose a hybrid motion estimation algorithm which puts computation resources to the most needed parts. Besides, a data re-use design is adopted to further reduce the complexity. As compared to the original SVC reference software, our encoder achieves about 9X speed-up without inducing serious quality degradation and compression ratio drop. With the increasing popularity of multi-processor systems and the maturity of thread libraries, parallel video encoding becomes a promising way to significantly speed-up the encoding process. However, conventional video encoders including the SVC reference software is single-threaded and can not take advantage of the multiprocessor systems. We propose a picture decomposition method based on the hierarchical B-picture structure of SVC. The proposed method outperforms traditional macroblock decomposition by about 10.1% in speed while producing exactly the same result. In addition, an efficient parallel algorithm for H.264/MPEG4-AVC deblocking filter is proposed. The content adaptive in-loop deblocking filter is complicated since every 4×4 block has to be examined by series of conditional checks. About one-third of the computation time is consumed in this module in an optimized H.264/MPEG4-AVC decoder. The high data dependency among filtering operations restricts efficient parallel algorithms which can fully utilize the multi-processor systems. The proposed parallel algorithm based on an essential observation named “limited error propagation effect” outperforms traditional wave-front method by about 40% in speed. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
| Externí odkaz: |
|