Many advanced video applications require manipulations of compressed video signals. Popular video manipulation functions include overlap (opaque or semi-transparent), translation, scaling, linear filtering, rotation, and pixel multiplication. In this paper, we propose algorithms to manipulate compressed video in the compressed domain. Specifically, we focus on compression algorithms using the Discrete Cosine Transform (DCT) with or without Motion Compensation (MC). Compression systems of such kind include JPEG, Motion JPEG, MPEG, and H.261. We derive a complete set of algorithms for all aforementioned manipulation functions in the transform domain, in which video signals are represented by quantized transform coefficients. Due to a much lower data rate and the elimination of decompression/compression conversion, the transform-domain approach has great potential in reducing the computational complexity. The actual computational speedup depends on the specific manipulation functions and ...

In this thesis, I investigate issues in the development of continuous media (CM) applications. CM applications process, transport, or store CM data such as digital audio and video. Introduction of video into applications will require support for sophisticated video effects such as image processing, composition and digital filtering. Traditional image processing and composition algorithms operate on uncompressed images, while video is typically stored and delivered in a compressed form. High computational cost, along with the complexity of video decompression, makes traditional algorithms too slow for interactive use on video data. This thesis describes and evaluates a new family of algorithms for computing video effects that run one to two orders of magnitude faster than their ...

An intermediate-level specification notation is presented for use with BSP-style programming. It is achieved by extending pre-post semantics to reveal state at points of global synchronisation. That enables us to integrate the pre-post, finite and reactive-process styles of specification in BSP, as shown by our treatment of the dining philosophers. The language is provided with a complete set of laws and has been formulated to benefit from a simple predicative semantics.

Current video compression formats optimize for either compression or editing. For example, motion-JPEG (MJPEG) provides excellent random access and moderate overall compression, while MPEG optimizes for compression at the expense of random access. Converting from one format to another, a process called transcoding, is often desirable over the life of a video segment. This paper shows how to transcode MPEG-1 video to motion-JPEG without fully decompressing the MPEG-1 source. The described technique for compressed domain transcoding differs from previous work because it uses a new approximation approach that is optimized for software implementations. This new approach is 1.5 to 3 times faster than spatial domain transcoders and offers an additional degree of freedom: higher transcoding speeds can be obtained at the price of lower picture quality. This speed/quality trade-off is useful in many real-time applications such as off-line editing and video gateways. 1. Introduction Motion-JPE...

This paper studies paralsg recursion. The trace speci#cationlpeci#c used in this paper incorporates sequential,j nondeterminism, reactiveness(inclvenessg,F'k traces), three forms of paral'VgJj (inclVgJjqMkEglglgl fair-interlkEglgl synchronous paralonousg and general recursion. In order to use Tarski's theorem to determine the #xpoints of recursions, we need to identify awelVjgJ,FIq partial order.Several orders are considered,incldered new order calrg the lexical order, which tends tosimulM, the execution of a recursion in asimilk manner as the EglVqgJ,E, order. A theorem of this paper shows that no appropriate order exists for the lhegIIIE Tarski's theoremalor is not enough to determine the #xpoints ofparalVI recursions. Instead of usingTarski's theoremdirectl, we reason about the #xpoints of terminatingand nonterminatingbehavioursseparateli Such reasoningis supported by the leg of a new compositioncalio partition. We propose a #xpoint techniquecalni the partitioned #xpoint, which is thelgqk #xpoint of the nonterminatingbehaviours after the terminatingbehaviours reach their greatest #xpoint. The surprisingresul is thataltg,M, a recursion may not beljV"EgJqVE' monotonic, it must have the partitioned #xpoint, which isequal to thelegj lgjIjI,gJqF' #xpoint. Since the partitioned #xpoint iswel de#ned in anycompl,q lmpl,q theresulq areappljFMgJ to various semanticmodeli Existing#xpoint techniquessimpl becomespecial cases of the partitioned #xpoint. Forexamplj an EglIIqgJq',EFglEFg recursion has itslsgj EglMMFIgJq #xpoint, which can be shown to be the same as the partitioned #xpoint. The new technique is moregeneral than thelegq EglEEkIgJq #xpoint in that the partitioned #xpoint can be determined even when a recursion is notEglVjjVgJq monotonic.Exampln of non-monotonic recur...

In this paper, we study the predicative semantics of different temporal logics and the relationships between them. We use a notation called generic composition to simplify the manipulation of predicates. The modalities of possibility and necessity become generic composition and its inverse of converse respectively. The relationships between different temporal logics are also characterised as such modalities. Formal reasoning is carried out at the level of predicative semantics and supported by the higher-level laws of generic composition and its inverse. Various temporal domains are unified under a notion called resource cumulation. Temporal logics based on these temporal domains can be readily defined, and their axioms identified. The formalism provides a framework in which human experience about system development can be formalised as refinement laws. The approach is demonstrated in the transformation from Duration Calculus to Temporal Logic of Actions. A number of common design patterns are studied. The refinement laws identified are then applied to the case study of water pump controlling.

Canonical trace model of Hoare and He supports a satisfactory theory of graph properties. We use it to define a technique for the general composition of properties that extends the parallel-by-merge of Unifying Theories of Programming, and apply that to unique decompositions.

This paper introduces techniques to organise predicate-semantic models in a hierarchical structure so that a new model can inherit the laws of more abstract ones. Generic composition is used to simplify the manipulation of predicates. Necessary restrictions are imposed on the definition of each model so that the inheritance relation can be established by checking a few conditions on the healthiness conditions and the commands.

Different temporal logics tend to emphasise different aspects of a hybrid system. In this paper, we study the predicative interpretation of Duration Calculus (DC) and Temporal Logic of Actions (TLA) and the link between them. A notation called generic composition is used to simplify the manipulation of predicates. The modalities of possibility and necessity become generic composition and its inverse of converse respectively. The transformation between different temporal logics is also characterised as such modalities. The formalism provides a framework in which human experience about hybrid system development can be formalised as refinement laws. A high-level durational specification can be decomposed to two durational specifications driven by an automaton. In such a stepwise design process, durational features are reduced while automaton features increase gradually. The application of the technique is demonstrated in the case study of the gas burner problem.

We apply Baxter algebras to the study of the umbral calculus. We give a characterization of the umbral calculus in terms of Baxter algebra. This characterization leads to a natural generalization of the umbral calculus that include the classical umbral calculus in a family of λ-umbral calculi parameterized by λ in the base ring. 1