A Mode Mapping and Optimized MV Conjunction Based H.264/SVC to H.264/AVC Transcoder with Medium-Grain Quality Scalability for Videoconferencing

作者：Sun Lei^*; Liu Zhenyu; Ikenaga Takeshi

来源：IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences, 2014, E97A(2): 501-509.

DOI：10.1587/transfun.E97.A.501

• SVC-to-AVC transcoding
• MGS scalability
• mode mapping
• MV conjunction
• videoconferencing

Scalable Video Coding (SVC) is an extension of H.264/AVC, aiming to provide the ability to adapt to heterogeneous networks or requirements. It offers great flexibility for bitstream adaptation in multi-point applications such as videoconferencing. However, transcoding between SVC and AVC is necessary due to the existence of legacy AVC-based systems. The straightforward re-encoding method requires great computational cost, and delay-sensitive applications like videoconferencing require much faster transcoding scheme. This paper proposes a 3-stage fast SVC-to-AVC transcoder with medium-grain quality scalability (MGS) for videoconferencing applications. Hierarchical-P structured SVC bitstream is transcoded into IPPP structured AVC bitstream with multiple reference frames. In the first stage, mode decision is accelerated by proposed SVC-to-AVC mode mapping scheme. In the second stage, INTER motion estimation is accelerated by an optimized motion vector (MV) conjunction method to predict the MV with a reduced search range. In the last stage, hadamard-based all zero block (AZB) detection is utilized for early termination. Simulation results show that proposed transcoder achieves very similar coding efficiency to the optimal result, but with averagely 89.6% computational time saving.

• 出版日期2014-2
• 单位清华大学