13476763
CPU/power-constrained mobile devices
Due to the limited processing capability, memory constraints, and the power budget of mobile clients, multimedia coders and/or decoders are often difficult to implement on wireless handheld PDAs. In this Universal Tuner project, we designed and implemented a wireless video streaming system that transcodes MPEG-1/2 videos or live TV broadcasting videos to the BW or indexed color Palm OS devices. In our system, the complexity of multimedia compression and decompression algorithms is adaptively partitioned between the encoder and decoder. A mobile client would selectively disable or reenable stages of the algorithm to adapt to the device's effective processing capability. Our variable-complexity strategy of selective disabling of modules supports graceful degradation of the complexity of multimedia coding and decoding into a mobile client's low-power mode, i.e. the clock frequency of its next-generation low power CPU has been scaled down to conserve power. We modified the structure of the standard motion-compensated DCT video codecs to implement a simplified the encoder on a PC server and the decoder on a complexity-constrained PDA viewing client.
26305379
A parallel decoding algorithm for IFS codes without transient behavior
Iterated function systems (IFSs) have received great attention in encoding and decoding fractal images. Barnsley (1988) has shown that IFSs for image compression can achieve a very high compression ratio for a single image. However, the major drawback of such a technique is the large computation load required to both encode and decode a fractal image. We provide a novel algorithm to decode IFS codes. The main features of this algorithm are that it is very suitable for parallel implementation and has no transient behavior. Also, from the decoding process of this method we can understand the encoding procedure explicitly. One example is illustrated to demonstrate the quality of its performance.
10271144
Robust image authentication method surviving JPEG lossy compression
Image authentication verifies the originality of an image by detecting malicious manipulations. This goal is different from that of image watermarking which embeds into the image a signature surviving most manipulations. Existing methods for image authentication treat all types of manipulation equally (i.e., as unacceptable). However, some applications demand techniques that can distinguish acceptable manipulations (e.g., compression) from malicious ones. In this paper, we describe an effective technique for image authentication which can prevent malicious manipulations but allow JPEG lossy compression. The authentication signature is based on the invariance of the relationship between DCT coefficients of the same position in separate blocks of an image. This relationship will be preserved when these coefficients are quantized in a JPEG compression process. Our proposed method can distinguish malicious manipulations from JPEG lossy compression regardless of how high the compression ratio is. We also show that, in different practical cases, the design of authenticator depends on the number of recompression times and on whether the image is decoded into integral values in the pixel domain during the recompression process. Theoretical and experimental results indicate that this technique is effective for image authentication.
8250531
Integrating Features, Models, and Semantics for TREC Video Retrieval
In this paper, we describe a system for automatic and interactive content-based retrieval of video that integrates features, models, and semantics. The novelty of the approach lies in the (I) semi-automatic construction of models of scenes, events, and objects from feature descriptors, and (2) integration of content-based and model-based querying in the search process. We describe several approaches for integration including iterative filtering, score aggregation, and relevance feedback searching. We describe our effort of applying the content-based retrieval system to the TREC video retrieval benchmark.
5783340
Zero-error information hiding capacity of digital images
We derive a theoretical capacity for digital image watermarking with zero transmission errors. We present three different discrete memoryless channel model to represent the watermarking process. Given the magnitude bound of noise set by applications and the acceptable watermark magnitude determined by the just-noticeable distortion, we estimate the zero-error capacity by applying Shannon's (1948) adjacency-reducing mapping technique. The capacity we estimate here corresponds to a deterministic guarantee of zero error, different from the traditional theorem approaching zero error asymptotically.
47470200
Multipurpose virtual-reality-based motion simulator
Public security has become an important issue everywhere. In particular, the safe manipulation and control of various machines and vehicles has gained special attention such that the authorities keep emphasizing the strict training and censoring of human operators. Currently, such training and censoring processes usually rely on the actual machines, equipment, or vehicles in the real sites. This not only has high demands in space, time and cost, but also causes another phase of public security problem. In connection with this, the world-wide trend is to tackle the above dilemma by using virtual reality (VR). However, the current VR research or products are more mature in the software display part of VR. How to combine a 3D VR display with a motion platform to achieve the aforementioned training and censoring purposes is an important research issue. The paper focuses on this research issue, and the goal is to develop a multipurpose virtual-reality-based motion simulation system to meet the requirements of public security in training and censoring of human operators.
9988109
An Adaptive Distance Learning System Based on Media Streaming
This paper presents the design and development of an adaptive real-time multimedia distance learning system:EasyLearning®, which supports both online learning and courseware on demand through the Internet. By combining the innovative ideas and best features of scalable video coding, screen share algorithm, session control signaling, and TCP-friendly multicast protocol, EasyLearning® is capable of achieving good Quality of Service (QoS) of video and audio, efficiency, and reliability of media delivery. According to the experimental comparison between EasyLearning® and Microsoft media service based system (MMS), Easylearning® provides better performance.
20511547
Recurrent learning algorithms for designing optimal controllers of continuous systems
Proposes a recurrent learning algorithm for designing the controllers of continuous dynamical systems in optimal control problems. The controllers are in the form of unfolded recurrent neural nets embedded with physical laws from classical control techniques. The learning algorithm is characterized by a double forward-recurrent-loops structure for solving both temporal recurrent and structure recurrent problems. The first problem results from the nature of general optimal control problems, where the objective functions are often related to (evaluated at) some specific time steps or system states only, causing missing learning signals at some steps or states. The second problem is due to the high-order discretization of continuous systems by the Runge-Kutta method that we perform to increase accuracy. This discretization transforms the system into several identical interconnected subnetworks, like a recurrent neural net expanded in the time axis. Two recurrent learning algorithms with different convergence properties are derived; first- and second-order learning algorithms. Their computations are local and performed efficiently as net signal propagation. We also propose two new nonlinear control structures for the 2D guidance problem and the optimal PI control problem. Under the training of the recurrent learning algorithms, these controllers can be easily tuned to be suboptimal for given objective functions. Extensive computer simulations show the controllers' optimization and generalization abilities.
14723095
Optimal Priority Packetization with Multi-layer UEP for Video Streaming over Wireless Network
Most of current packetization schemes consider only bit error or packet erasure, both of which are common in wireless networks. This paper addresses these two problems together, and proposes an optimal packetization scheme for video streaming over wireless network, which is independent of video coding method. To combat the packet erasure, priority packetization combined with multi-layer unequal error protection (UEP) is applied on video frames. Multi-layer UEP contains low-complexity duplication of high-priority packet in application layer and different retransmission limit in media access control layer. Content-aware rate-distortion optimization is also introduced in order to countermine the distortion caused by bit errors. Simulations show that our scheme gains 2.17 dB or more compared with the conventional scheme.
12795062
Mutually independent hamiltonian paths in star networks
Two hamiltonian paths P1 = 〈u1, u2, . . . , un(G)〉 and P2 = 〈v1, v2, . . . , vn(G)〉 of G from u to v are independent if u = u1 = v1, v = vn(G) = un(G), and vi = ui for every 1 < i < n(G). A set of hamiltonian paths, {P1, P2, . . . , Pk }, of G from u to v are mutually independent if any two different hamiltonian paths are independent from u to v . A bipartite graph G is hamiltonian laceable if there exists a hamiltonian path joining any two nodes from different partite sets. A bipartite graph is k -mutually independent hamiltonian laceable if there exists k -mutually independent hamiltonian paths between any two nodes from distinct partite sets. The mutually independent hamiltonian laceability of a bipartite graph G, IHPL(G), is the maximum integer k such that G is k -mutually independent hamiltonian laceable. Let Sn denote the n-dimensional star graph. We prove that IHPL(S2) = 1, IHPL(S3) = 0, and IHPL(Sn) = n − 2 if n ≥ 4. © 2005 Wiley Periodicals, Inc. NETWORKS, Vol. 46(2), 110–117 2005