Low-complexity video error concealment for mobile applications using OBMA

Video transmission over wireless networks becomes a major part of multimedia studies especially after fourth-generation communication standard has been introduced. There is a growing need to improve video visual quality, while its computational complexity should remain low. One of the low-complexity Error Concealment (EC) methods for missing macroblock (MB) recovery is Boundary Matching Algorithm (BMA). Nevertheless, this method suffers from lack of accuracy. In this paper, we propose a novel modified BMA method by exploiting the correlation of the pixels on the edge of the missing MB. The performance of this method is explained in detail and extra experimental results are given to demonstrate its superiority over BMA method.

We use particle filtering for correcting the erroneous motion vectors (MVs), which are derived from the boundary matching algorithm (BMA) in packet video communications. Assuming a two-state Markov channel model for transmission, the error of the extracted MVs by BMA is shown to be modeled by the Gaussian mixture distribution. Formulating the problem in the state space, we deploy particle filtering for denoising the erroneous MVs. The main challenge of using particle filters is high computational complexity that is directly related to the number of particles. The proposed particle filtering scheme is efficient even if the number of particles is decreased. Experimental results are provided to show the efficiency of this filtering approach compared to a recent scheme based on Kalman filtering. The experiments show meaningful increase in the quality of the recovered video sequences in terms of PSNR up to 3 dB compared with the other error concealment techniques. Also, the computational complexity of the proposed scheme is discussed.

Error concealment at a decoder is an efficient method to reduce the degradation of visual quality caused by channel errors. In this paper, we propose a novel spatio-temporal error concealment algorithm based on the spatial-temporal fading (STF) scheme which has been recently introduced. Although STF achieves good performance for the error concealment, several drawbacks including blurring still remain in the concealed blocks. To alleviate these drawbacks, in the proposed method, hybrid approaches with adaptive weights are proposed. First, the boundary matching algorithm and the decoder motion vector estimation which are well-known temporal error concealment methods are adaptively combined to compensate for the defect of each other. Then, an edge preserved method is utilized to reduce the blurring effects caused by the bilinear interpolation for spatial error concealment. Finally, two concealed results obtained by the hybrid spatial and temporal error concealment are pixel-wisely blended with adaptive weights. Experimental results exhibit that the proposed method outperforms conventional methods including STF in terms of the PSNR performance as well as subjective visual quality, and the computational complexity of the proposed method is similar to that of STF.

Purpose – The purpose of this paper is to solve the pack loss problem of video transmitted over error‐prone channels. Pack loss generally affects the visual quality of reconstructed frames significantly. Consequently, a grey approach to error concealment (EC) is proposed.Design/methodology/approach – Note that missing information in error blocks can be found before and after the error frame. Thus, two adjacent error‐free frames are utilized to conceal error blocks caused by packet loss. This paper presents an EC approach based on grey polynomial interpolation (GPI) which is called the GTEC. In the GTEC, the following stages are involved. First, error blocks due to packed loss are detected. Then, optimal reference blocks in adjacent frames are found through boundary matching algorithm (BMA). Finally, estimated blocks are obtained by the GPI. By replacing error blocks with the estimated blocks, EC is completed in the GTEC.Findings – In the simulation, the proposed GTEC is compared with the EC scheme in H.26...

Capturing or acquiring video data from advanced gadgets, like cell phone cameras, smart phones, camcorders, etc., is very recent and up growing trend. With the advancement of the video camera as the integrated part of these multimedia devices generates necessity for video stabilization. Digital video stabilization or video frame alignment techniques are used to improve quality of input video by removing the undesired camera motions jitters; undesirable jiggles etc. Many video stabilization techniques are developed till now but only fast and low computational complexity approaches can be applied on the embedded devices. The paper presents the review of fast block matching local motion vector estimation and alignment algorithm. Effectiveness of the algorithm is shown by quantitative evaluation. The proposed work will also help to boost the performance of various error concealment, error resilience and video quality improvement techniques in H.264/HEVC video codec.

Occupation is recognized as a modifiable factor related to cognitive reserve in older adults. To examine the association between levels of complexity in lifelong occupations and cognitive performance in later life. A cross-sectional study of older adult users (aged 65 or more) of a private health care plan, resident in the north zone of Rio de Janeiro City, Brazil, and participating in the Rio de Janeiro section of the Study of Fragility in Brazilian Older Adults (FIBRA-RJ). Cognitive performance scores were obtained using the Mini-Mental State Examination. The level of complexity of their work was assessed in three domains: work with data, persons and things. Associations between the complexity of work in each domain and cognitive performance were evaluated using multivariate linear regression, adjusted for socio-demographic variables and duration of occupation. A total of 624 older adults (94% of the study group) performed lifelong work activities. Among those working with data, the high complexity group had cognitive performance scores 1.08 points higher (P < 0.05) than low complexity. In work with things, scores in the intermediate complexity group were 0.53 points higher (P < 0.05) than low complexity. There was no statistically significant difference in the cognitive performance between levels of complexity of work with people. Complexity in work with data and things was associated with better cognitive performance in later life, independent of age, schooling, income and duration of occupation.

Optimal resynchronization marker positioning method using a novel information measure

Concerning the video quality decline caused by damaged macroblocks in video transmission,this paper modified the boundary matching algorithm by adopting the interlaced weighted double error concealment scheme,inducted the motion vector estimation selectively,and used 8×8 subblocks correlation error concealment mode when the boundary matching error of the predictive block was higher than a given threshold.Experimental results show that the proposed algorithm could averagely raise the PSNR about 1 dB and correspondingly improve the decoded video quality effectively.

Consecutive corrupted MBs or slice errors are commonly seen in modern video transmission systems. Temporal error concealment is an effective approach to reduce the impact of errors. Conventional temporal error concealment techniques recover slice errors on a MB basis. We propose a new novel temporal scheme for slice error concealment based on a size-adaptive region basis. Size-adaptive region boundary matching can significantly reduce the misalignments or side mismatches that are commonly seen in MB-based approaches. Instead of using MSE or MAE as the matching criteria, We propose a matching criterion based on structural similarity (SSIM). Our proposed matching criterion can achieve better structural alignments and better visual perceptual quality. We also propose a method to detect motion vector outliers at the last stage of the error concealment scheme, which can further improve the visual quality of the concealed videos. Our proposed scheme conceals slice errors with good accuracy as well as low computation complexity, and it can be applied for real-time applications.

H.264 adopts new coding tools such as intra-prediction, variable block size, motion estimation with quarter-pixel-accuracy, loop filter, etc. The adoption of these tools enables an H.264-coded bitstream to have more information compared with previous standards. In this paper we proposed an effective spatial error concealment method with low complexity. Among the information included in an H.264-coded bitstream, we use prediction modes of intra-blocks for recovering a damaged block. This is because a prediction direction in each prediction mode is highly correlated to the edge direction. We first estimate the edge direction of a damaged block using prediction modes of intra-blocks adjacent to a damaged block and classify the area inside a damaged block into the edge and the flat area. And then our method recovers pixel values in the edge area using edge-directed interpolation, and recovers pixel values in the flat area using weighted interpolation. Simulation results show the proposed method yields better video quality than conventional approaches.

The quest to identify factors responsible for efficient and effective organisation behaviour has led to the growth of a body of literature known as leadership research, and a recurring theme of interest include that of leadership attributes. This study aims to make a contribution to this area of work by providing a profile on the cognitive disposition of "cognitive complexity" of a group of pre-service recreation managers. Garder (1986) made the distinction between "leader managers" and "routine managers" by asserting that the former possess qualities which allow them to exhibit what Bass (1985) calls "Transformational Leadership". For some years, leadership research has been trying to produce explanatory accounts for efficient and effective leadership behaviours and it appears that a more recent theory of its kind is the transformational leadership theory proposed by Bass (1985). Hater and Bass (1988) suggested that transformational leaders should exhibit superior performance ability in making judgement, decisions, and analysis. Kotter (1990) further added that the ability to "gather a broad range of data and look for patterns, relationships, and linkages that help explain things" (p. 104) is one important but basic element for becoming an exceptional leader. Given that these are the behavioural outcomes of "manager leaders", a question of interest would be to identify the cognitive dispositions responsible for these overt behaviours. Cognitive complexity, a cognitive disposition, has been defined as a person's "capacity to construe social behaviour in a multidimensional way" (Bieri, Atkins, Briar, Leaman, Miller, &amp; Tripodi, 1975, p. 185). This suggests that level of cognitive complexity may have a bearing on a person's ability to process multidimensional information such that a cognitively more complex person may have a more differentiated perception of a person, object, or situation than a cognitively less complex person. Within these premises, it could be argued that level of cognitive complexity, acting as a mediator in the input-output process of cognitive functions, may also influence an individual's cognitive outcomes. In fact, this contention finds support in previous studies such as those by Tripodi and Bieri (1964), Hale (1980) and Kishor (1990) which had identified a positive relationship between level of cognitive complexity and superior cognitive outcomes. In a more recent study, Spengler and Strohmer (1994) compared high and low scorers of a cognitive complexity test and found that individuals with lower cognitive complexity scores were more likely to form biased judgements. Given the influence of cognitive complexity in making judgements and appraisals and the administrative challenges faced by today's recreation managers, the need to preview the status of this cognitive disposition among future recreation leaders is tempting. For a practical and application viewpoint, information from this study might provide some insight into impending programme needs and directions for future foci. (Abstract taken from Introduction)

Recognition and understanding human activity is a challenging research topic for the last 30 years with significant advances, but with major open problems to be solved. Researchers have proposed a variety of advanced methodologies by approaching this interesting topic from a single direction. By saying a single direction we mean using either formal or statistical approaches. These approaches have their own limitations like the formal approaches cannot scale up beyond a certain level of complexity while the statistical ones don’t work well in low complexities [1]. Thus, a possible solution is the use of a synergistic approach based on the efficient combination of formal and statistical methods. In this chapter, the authors offer a formal-statistical AI tool for the recognition of complex human activities. The formal model is associated with three context-free languages at body, motion, and activity levels. The statistical model is an artificial network that learns the activity of the human body.

We present a low complexity approach for the estimation of the temporal and spatial activity parameters of videos which are captured by a front-facing camera of a vehicle based on context information of the vehicle. The estimated parameters are integrated into an objective video quality metric, which can be used to determine the perceptual quality of a compressed video stream. Our proposed video quality metric has very low computational complexity, which makes it suitable for live video streaming applications. It shows a high Pearson correlation of 0.98 with an average root-mean-square error of 6%, as verified by statistical analysis with data from subjective tests.

When Ss view less complex geometric shapes longer than they do more complex ones when the instruction is for the inverse effect occurs but Ss reverse this preference, in favor of the more complex shapes, when viewing for In an earlier viewing-time study Ss were exposed to the same randomly generated and distrib uted polygons twice (Kirkland, 1974). As that study was designed to examine sequential effects Ss received different instructions in each phase. The inverse effect occurred only when the instruction of preceded the instruction of Interest. The present study reports sequential effects obtained with rating scales and a group administration procedure. Two intact and independent mixed-sex groups of 15 Ss (M.A. and Diploma of Education srudents) in each were formed: 8 males in the Pleasure-to-Interest group and 6 males in the reverse instructional group. Five-page booklets were randomly distributed in each of two separate sessions. An identical cover-page contained general instructions and an example of the 7-point rating scales with two end anchors: 1 = least, 7 = most. In half these booklets the subsequent pair of pages were exchanged for the final pair to ensure balance within sessions. The first member of each pair instructed Ss to rate either for Interest or for Aesthetic Pleasure. The second member contained all the appropriately labelled rating scales. Between each experimental phase Ss were told the study was not related to memory testing. The stimuli and the order of stimuli between phases have been described previously. All slides were displayed for 4 sec. each. Dependent variables were S's mean ratings given to high and low complexity polygons under each instruction. Analyses were by 3-way analysis of variance. Separate analysis was run for each group where Ss were crossed with instruction and level of polygon complexity. Only the critical interaction of instruction by polygon complexity (demonstrating the inverse effecc) is relevant. This interaction was significant only for the Pleasure-to-Interest group (RJ, = 17.19, p < .01; with means for Pleasure; low complexity = 3.36 and high complexity = 3.83 and, for Interest; low complexity = 3.22 and high complexity = 5.56). These results support the suggestion that aesthetic pleasure may be considered as a subset of interest. It appears that instruction to view or rate Interest is more demanding of assimilatory cognitive processes than is either viewing or rating the same shapes for Aesthetic Pleasure (Berlyne, 1971). But once Interest demands have been made they will affect subsequent viewings or ratings.

Abordaje de la complejidad psicosocial en pacientes con cáncer