27968633
AVS-M: From Standards to Applications
AVS stands for the Audio Video coding Standard Workgroup of China, who develops audio/video coding standards as well as system and digital right management standards. AVS-M is the AVS video coding standard targeting for mobile multimedia applications. Besides the coding specification, AVS also developed the file format and Real-time Transport Protocol (RTP) payload format specifications to enable the application of AVS-M video in various services. This paper reviews the high-level coding tools and features of the AVS-M coding standard as well as the file format and payload format standards. In particular, sixteen AVS-M high-level coding tools and features, which cover most of the high-level topics during AVS-M standardization, are discussed in some detail. After that, the error resilience tools are briefly reviewed before the file format and RTP payload format discussions. The coding efficiency and error resiliency performances of AVS-M are provided finally. H.264/AVC has been extensively used as a comparison in many of the discussions and the simulation results.
14888347
Error Resilient Mode Decision in Scalable Video Coding
Error resilient macroblock mode decision has been extensively investigated in the literature for single-layer video coding, for which error resilient mode decision is also called as intra refresh. In this paper, we present a loss-aware rate-distortion optimized macroblock mode decision algorithm for scalable video coding, wherein more macroblock coding modes than intra and inter are involved. Thanks to the good performance, the proposed method has been adopted into the joint scalable video model by the joint video team.
14856574
Error Resilient Video Coding Using Unequally Protected Key Pictures
This paper proposes the use of unequally protected key pictures to prevent temporal error propagation in error-prone video communications. The key picture may either be an intra-coded picture or a picture using a long-term motion compensation reference picture through reference picture selection. The inter-coded key picture uses previous key pictures as motion compensation reference. Key pictures are better protected than other pictures using forward error correction in either source or transport coding. Simulation results show significantly improved error resiliency performance of the proposed technique compared to conventional methods.
15352869
Error Resilient Video Coding using Redundant Pictures
Coding of redundant pictures is supported in the latest international video coding standard H.264 (also known as MPEG-4 part 10 or AVC). This paper proposes a standard-compliant way to encode and decode redundant pictures for improved error resilience. The method is based on a combination of picture-level reference picture selection, reference picture list ordering, and a hierarchical allocation of redundant pictures, which can efficiently prevent temporal error propagation without relying on feedback information. Simulation results show that the method outperforms the optimal loss-aware rate-distortion optimized intra refresh method. The proposed algorithm has been adopted into the H.264 joint model.
2496902
Improved Error Concealment Using Scene Information
Signaling of scene information in coded bitstreams was proposed by the authors and adopted into the emerging video coding standard H.264 (also known as MPEG-4 part 10 or AVC) as a supplemental enhancement information (SEI) message. This paper proposes some improved error concealment methods for intra coded pictures and scene transition pictures using the signaled scene information. Simulation results show that the proposed methods outperform conventional techniques significantly.
36989079
Sub-picture: ROI coding and unequal error protection
Region-of-interest coding and unequal error protection are two important tools in video communication systems to improve the received visual quality. One common property of the two techniques is that unequal coding or transmission is applied to improve the quality of the most important parts of images. The proposed sub-picture coding technique facilitates both region-of-interest coding and unequal error protection by partitioning images to regions of interest and separating the corresponding coded data units from each other. Simulation results show that the overall subjective quality is considerably improved compared to the conventional coding schemes.
14266211
Efficient algorithms for minimum congestion hypergraph embedding in a cycle
The minimum congestion hypergraph embedding in a cycle (MCHEC) problem is to embed the hyperedges of a hypergraph as paths in a cycle with the same node set such that the maximum congestion (the maximum number of paths that use any single edge in the cycle) is minimized. The MCHEC problem has many applications, including optimizing communication congestions in computer networks and parallel computing. The problem is NP-hard. In this paper, we give a 1.8-approximation algorithm for the MCHEC problem. This improves the previous 2-approximation results. Our algorithm has the optimal time complexity O(mn) for a hypergraph with m hyperedges and n nodes. We also propose an algorithm which finds an embedding with the optimal congestion L* for the MCHEC problem in O(n(nL*)/sup L*/) time. This improves the previous O((mn)/sup L*+1/) time algorithm.
19029975
Design and Implementation of an Automatic RTPA Code Generator
Real-time process algebra (RTPA) is a mathematics-based notation system for the specification and refinement of realtime and safety-critical systems. This paper presents the work on designing and developing a set of tools that facilitate automatic generation of C++ code from RTPA specifications of system architectures and behaviors. A two-phrase strategy has been employed in the design of the toolkit. In the first phrase, an RTPA specification is lexically and syntactically analyzed and type-checked, which results in a set of abstract syntax trees. In the second phrase, C++ code is generated using the RTPA-to-C++ mapping strategies and patterns when walking down the abstract syntax trees. The RTPA-to-C++ mapping strategies specify both the traditional sequential part of RTPA mapping onto the standard C++ library and the real-time features of RTPA, such as interrupt, concurrency, duration, and event/time-driven dispatch, mapping onto the RTPA run-time library, which provides real-time support and is implemented using real-time kernel techniques. The toolkit implemented includes an RTPA lexer, an RTPA parser, an RTPA type-checker, and an RTPA code-generator. The experimental results show that RTPA specifications can be rigorously checked and corresponding C++ code can be automatically generated from RTPA specifications using the toolkit. The automatically generated code is executable and effective under the support of the standard C++ library and the specially developed RTPA run-time library
14022565
Semantic Structure Matching for Assessing Web-Service Similarity
The web-services stack of standards is designed to support the reuse and interoperation of software components on the web. A critical step in the process of developing applications based on web services is service discovery, i.e., the identification of existing web services that can potentially be used in the context of a new web application. UDDI, the standard API for publishing web-services specifications, provides a simple browsing-by-business-category mechanism for developers to review and select published services. To support programmatic service discovery, we have developed a suite of methods that utilizes both the semantics of the identifiers of WSDL descriptions and the structure of their operations, messages and data types to assess the similarity of two WSDL files. Given only a textual description of the desired service, a semantic information-retrieval method can be used to identify and order the most similar service-description files. This step assesses the similarity of the provided description of the desired service with the available services. If a (potentially partial) specification of the desired service behavior is also available, this set of likely candidates can be further refined by a semantic structure-matching step assessing the structural similarity of the desired vs. the retrieved services and the semantic similarity of their identifier. In this paper, we describe and experimentally evaluate our suite of service-similarity assessment methods.
1436962
Predicting query times
We outline the need for search engines to provide user feedback on the expected time for a query, describe a scheme for learning a model of query time by observing sample queries, and discuss the results obtained for a set of actual user queries on a document collection using the MG search engine.
21557809
Formal description of the cognitive process of problem solving
One of the fundamental human cognitive processes is problem solving. Most of the decisions we make relate to some kind of problems we try to solve no matter how trivial and critical the problem may be. The problem solving process entails performing in a new situation with information acquired and knowledge learned from past situations. As a higher level cognitive process, problem solving involves the correlation process effort to connect newly encounter problem object(s) with the object-attribute-relation (OAR) model representation of knowledge in the brain. The goal of problem solving is to search along various solution paths within the problem solver's knowledge base in the memory. When a problem object is identified, problem solving can be perceived as a search process in the memory space for finding a relationship between a set of problem-solving goals and a set of alternative paths. This paper presents a mathematical and cognitive model that describes problem solving as a cognitive process. The cognitive structures of the brain and the mechanisms of internal knowledge representation behind the cognitive process of problem solving are explained. The cognitive process is then formally and rigorously described using real-time process algebra (RTPA) base on the aforementioned models. Extended discussions are presented on applications of the cognitive process model of problem solving in software engineering and psychology.