No abstract

No abstract

The H.264/AVC standard defines an optional in-loop deblocking filter. The effect of this filter on subjective video quality is investigated. Filter settings preferred by users are recorded for a group of 82 users across a range of video sequences and coded bitrates. The results indicate two clear groupings of user preferences for low-and medium-activity sequences. There is no clear user preference when the sequence contains high motion and activity. The implications of these results for performance optimisation of H264/AVC CODECs are discussed.

No abstract

Many real systems are difficult to model and control due to incomplete knowledge of the system behavior and the availability of only short-term or unreliable data records. Hence, the uncertainty, which results from both the measurement and modeling process, should be taken into account when making predictions or designing systems.Although this type of analysis, from input to output, can provide useful information to the decision-maker, we present an approach in which the inverse problem (robust design) can also be solved especially when there are specifications or constraints for the outputs. That is, we move from output to input and determine the effect of such specification in the inputs.This paper proposes innovative approaches based on the use of Interval Arithmetic (IA) and Cellular Evolutionary Strategies (CES) as alternative techniques to perform sensitivity and uncertainty analysis and to obtain robust system design. The proposed approaches are powerful tools that the decision-maker should use to validate and design any kind of systems.Interval Arithmetic is an alternative technique to find the sensitive elements of a design, to calculate how system accuracy varies as parameters vary. IA is able to consider simultaneously the effects of uncertainty of all of the parameters on a system accuracy and to provide strict bounds (the minimum and maximum values) with only one evaluation. CES are a recent approach that combines the Evolution Strategy techniques with concepts from Cellular Automata in order to obtain, by an iterative process, the maximum size of each deviation (robust design), while IA is used as a checking technique that guarantees the feasibility of the design.The approach used is an indirect method based on optimization instead of a direct method based on mapping from the output into the input space. CES does not rely on mathematical prerequisites to be applied and can be used for linear and non-linear constraints. The proposed approach is illustrated by an example applied to a circuit system. Results are compared with those obtained using a general non-linear optimization package.