Word-level Symbolic Trajectory Evaluation

Symbolic trajectory evaluation (STE) is a model checking technique that has been successfully used to verify industrial designs. Existing implementations of STE, however, reason at the level of bits, allowing signals to take values in {0, 1, X}. This limits the amount of abstraction that can be achieved, and presents inherent limitations to scaling. The main contribution of this paper is to show how much more abstract lattices can be derived automatically from RTL descriptions, and how a model checker for the general theory of STE instantiated with such abstract lattices can be implemented in practice. This gives us the first practical word-level STE engine, called STEWord. Experiments on a set of designs similar to those used in industry show that STEWord scales better than word-level BMC and also bit-level STE.Comment: 19 pages, 3 figures, 2 tables, full version of paper in International Conference on Computer-Aided Verification (CAV) 201

Digital Image Coding For Robust Multimedia Transmission

This paper presents an alternative to the above techniques for providing robust digital image transmission --- reconstruction of lost information from correctly received information. As such, reconstruction for robust transmission requires no special FEC or protocol features. Image data is highly correlated, and when the properties of the human visual system are considered, lost visual data can be reconstructed from received data such that the reconstructed data is reasonably correct (high PSNR) and visually pleasing. These two criteria are not the same --- it is possible to have a higher PSNR with a visually less pleasing result, and a lower PSNR with a better looking result. Providing reconstruction capability as well as compression places requirements on coding of the image data, where coding is defined to include both the actual source coding and the This document was created with FrameMaker 4.0.2 packetization of the compressed data. This paper describes coding of digital images that considers not only compression but also ease and quality of reconstruction to allow for robust transmission. Block-based transform coding techniques are considered so that direct extensions to JPEG-like and MPEG-like coding are possible. First, the trade-offs among decoder computation, transmission bandwidth, and visual quality are described, leading to two approaches to providing robust image transmission. Next, packetization requirements for reconstruction are considered. An approach to block-based reconstruction is described, and three specific solutions are given as examples, requiring different combinations of transmission bandwidth and decoder computation and all providing good visual quality. The reconstruction techniques presented are non-iterative and computationally efficie..

Fast Motion Estimation and Intermode Selection for H.264

<p/> <p>H.264/AVC provides various useful features such as improved coding efficiency and error robustness. These features enable mobile devices to adopt H.264 standard to achieve effective video communications. However, the encoder complexity is greatly increased mainly due to motion estimation (ME) and mode decision. In this paper, we propose a new scheme to jointly optimize intermode selection and ME using the multiresolution analysis. Experimental results show that the proposed method is over 3 times faster than other existing methods while maintaining the coding efficiency.</p