Transcoding And Its Applications In Scalable Video Coding

With the fast development of network and multimedia techniques,multimedia applications based on networks has been widely applied into everyday life.There are mainly three characteristics in the current multimedia application environment: heterogeneous networks,various receiving terminals and diversity of multimedia application categories.These features lead to difficulties as well as challenges within multimedia applications.Scalable video coding,which contains multiple sub-bitstreams for different temporal,spatial and quality scalabilities,differs greatly from traditional single-layer coding,and is adaptive to above environments.On the other hand,video transcoding,which has excellent coding performance and was also studied for years,can convert one signal to another according to various user requirements,thus is an ideal alternation.These two are the key techniques to solve above problems,and are the hot spots in research area of video processing and communication.They are considered as two promising techniques in theory and practice.Under the latest framework of Scalable Video Coding(SVC) extension of H.264/AVC,the dissertation analyzes its technical features and application scenarios, and studies related video transcoding techniques,for the purpose of solving various problems in video transcoding under different network environments,user experiences and coding formats.The main contents and novelties of the dissertation are as follows:1.Makes comprehensive technical comparisons between SVC and video transcoding.This dissertation studies SVC from theoretical analysis to practical simulations within broad categories of video contents,and makes comparisons between SVC and video transcoding in terms of encoder complexity,coding performance,decoder complexity,scalability scale,etc.With the above detailed comparisons and data analysis,the pros and cons of SVC are pointed out,which can be considered as theoretical analysis and data support for the potential application scenarios of SVC.2.Proposes a general spatial resolution transcoding framework to H.264/AVC video format,as well as algorithms.The dissertation studies the spatial resolution transcoding process from SVC to H.264/AVC,analyzes the commonness and differences between them,and proposes a general fast spatial resolution transcoding architecture from SVC to H.264/AVC format.It focuses on pixel-domain fast motion estimation,fast mode decision,and motion re-using techniques.Under this brand-new SVC-to-H.264/AVC spatial transcoding architecture,excellent transcoding performance is obtained while maintaining low complexity.3.Proposes a general method for comprehensive video transcoding from SVC to H.264/AVC video format,together with other techniques.With proposed spatial transcoding architecture mentioned above,the dissertation studies the transcoding process from SVC to H.264/AVC in terms of bitrate transcoding,and proposes a spatial-quality combined comprehensive transcoding framework and related algorithms.The new framework studies transcoding techniques on both open-loop and closed-loop transcoding fields.In addition, considering bitrate reduction,the dissertation proposes a bottom-up fast mode decision algorithm.These techniques can realize real-time spatial and quality video transcoding while maintaining acceptable performance loss,thus making a satisfactory tradeoff between transcoding performance and transcoding complexity.In conclusion,this dissertation investigates the latest SVC standard,and builds up new architectures combining SVC and transcoding for the purposes of spatial and quality transcoding.Some useful and encouraging results have been obtained.