Error resilient video transcoding for robust inter-network communications using GPRS

A novel fully comprehensive mobile video communications system is proposed in this paper. This system exploits the useful rate management features of the video transcoders and combines them with error resilience for transmissions of coded video streams over general packet radio service (GPRS) mobileaccess networks. The error-resilient video transcoding operation takes place at a centralized point, referred to as a video proxy, which provides the necessary output transmission rates with the required amount of robustness. With the use of this proposed algorithm, error resilience can be added to an already compressed video stream at an intermediate stage at the edge of two or more different networks through two resilience schemes, namely the adaptive intra refresh (AIR) and feedback control signaling (FCS) methods. Both resilience tools impose an output rate increase which can also be prevented with the proposed novel technique in this paper. Thus, an error-resilient video transcoding scheme is presented to give robust video outputs at near target transmission rates that only require the same number of GPRS timeslots as the nonresilient schemes. Moreover, an ultimate robustness is also accomplished with the combination of the two resilience algorithms at the video proxy. Extensive computer simulations demonstrate the effectiveness of the proposed system

Multiple description video coding for stereoscopic 3D

In this paper, we propose an MDC schemes for stereoscopic 3D video. In the literature, MDC has previously been applied in 2D video but not so much in 3D video. The proposed algorithm enhances the error resilience of the 3D video using the combination of even and odd frame based MDC while retaining good temporal prediction efficiency for video over error-prone networks. Improvements are made to the original even and odd frame MDC scheme by adding a controllable amount of side information to improve frame interpolation at the decoder. The side information is also sent according to the video sequence motion for further improvement. The performance of the proposed algorithms is evaluated in error free and error prone environments especially for wireless channels. Simulation results show improved performance using the proposed MDC at high error rates compared to the single description coding (SDC) and the original even and odd frame MDC

An enhanced reconstruction algorithm for unidirectional Distributed Video Coding

Distributed Video Coding (DVC) is an emerging video coding technology that utilizes the distributed source coding principles to build very low cost video encoders, yet with remarkable error resilience. In the common DVC framework, the reconstruction function plays a vital role that has a direct impact on the output video quality. In this paper, a novel algorithm is proposed for the reconstruction function, particularly focusing on the unidirectional DVC architecture. The proposed technique exploits the variations of the bit error rate of the Wyner-Ziv decoded bit stream and the side information stream. The simulation results show that the proposed algorithm yields a significant improvement of the objective and subjective video quality at no additional bit rate cost

Low-delay random view access in multi-view coding using a bit-rate adaptive downsampling approach

In this paper, a new multi-view coding (MVC) scheme is proposed and evaluated. The scheme offers improved low-delay view random access capability and at the same time comparable compression performance with respect to the reference multi-view coding scheme currently used. The proposed scheme uses the concept of multiple-resolution view coding, exploiting the trade-off between quantization distortion and downsampling distortion at changing bit-rates, which in turn provides improved coding efficiency. Bi-predictive (B) coded views, used in the conventional MVC method, are replaced with predictive coded downscaled views, reducing the view dependency in a multi-view set and hence reducing the random view access delay, but preserving the compression performance at the same time. Results show that the proposed method reduces the view random access delay in a MVC system significantly, but has a similar objective and subjective performance with the conventional MVC method

Enhancing Wireless Video Transmissions in Virtual Collaboration Environments

This paper introduces the virtual collaboration environment and discusses the problems encountered in wireless video transmissions of the participating users. Different schemes are proposed and evaluated to address various problems encountered in the wireless access links of the virtual collaboration system for enhancing the perceived visual quality. The schemes include radio network resource optimization, optimal joint source and channel rate allocation and error resilience enhancement using SVC-MDC. These schemes have been shown to offer a strong potential to be incorporated in a virtual collaboration system for quality enhancement

The role of the dentate gyrus and adult neurogenesis in hippocampal-basal ganglia associated behaviour

The ability of the brain to continually generate new neurons throughout life is one of the most intensely researched areas of modern neuroscience. While great advancements in understanding the biochemical mechanisms of adult neurogenesis have been made, there remain significant obstacles and gaps in connecting neurogenesis with behavioural and cognitive processes such as learning and memory. The purpose of the thesis was to examine by review and laboratory experimentation the role of the dentate gyrus and of adult neurogenesis within the hippocampus in the performance of cognitive tasks dependent on the hippocampal formation and hippocampal-basal ganglia interactions. Advancement in understanding the role of neurogenesis in these processes may assist in improving treatments for common brain injury and cognitive diseases that affect this region of the brain. Mild chronic stress reduced the acquisition rate of a stimulus-response task (p=0.043), but facilitated the acquisition of a discrimination between a small and a large reward (p=0.027). In locomotor activity assays, chronic stress did not shift the dose-response to methamphetamine. Analysis of 2,5-bromodeoxyuridine incorporation showed that, overall, chronic mild stress did not effect survival of neuronal progenitors . However, learning of the tasks had a positive influence on cell survival in stressed animals (p=0.038). Microinjections of colchicine produced significant lesions of the dentate gyrus and surrounding CA1-CA3 and neocortex. Damage to these regions impaired hippocampal-dependent reference memory (p=0.054) while preserving hippocampal independent simple discrimination learning. In a delay discounting procedure, the lesions did not induce impulsive-like behaviour when delay associated with a large reward was introduced. The experiments uphold a current theory that learning acts as a buffer to mitigate the negative effects of stress on neurogenesis

Barriers to virtual collaboration

This paper reports on the implementation and use of a virtual collaboration system - a virtual collaborative desk (VCD) that has been introduced to a software design team in an organizational context. Virtual collaboration systems are complex and can be considered as social-technical systems, oftentimes encompassing several layers of both technical and social issues. If this multi-layered social-technical system is to work effectively and provide a dependable service, then all the layers must be well understood and structured accordingly. Otherwise, these layers can become barriers to virtual collaboration if they impede the collaborating users of a virtual team from attaining their goals. An amalgamation of principles from life-cycle and ethnomethodologically informed ethnography approaches in the evaluation of a virtual collaborative system is demonstrated in a case-study to enable researchers to understand what these issues are and how the different types of issues can prevent effective virtual collaboration

Generation of non-repetitive everyday impact sounds for interactive applications

The use of high quality sound effects is growing rapidly in multimedia, interactive and virtual reality applications. The common source of audio events in these applications is impact sounds. The sound effects in such environments can be pre-recorded or synthesized in real-time as a result of a physical event. However, one of the biggest problems when using pre-recorded sound effects is the monotonous repetition of these sounds which can be tedious to the listener. In this paper, we present a new algorithm which generates non-repetitive impact sound effects using parameters from the physical interaction. Our approach aims to use audio grains to create finely-controlled synthesized sounds which are based on recordings of impact sounds. The proposed algorithm can also be used in a large set of audio data analysis, representation, and compression applications. A subjective test was carried out to evaluate the perceptual quality of the synthesized sounds

Generation of non-repetitive everyday impact sounds for interactive applications

The use of high quality sound effects is growing rapidly in multimedia, interactive and virtual reality applications. The common source of audio events in these applications is impact sounds. The sound effects in such environments can be pre-recorded or synthesized in real-time as a result of a physical event. However, one of the biggest problems when using pre-recorded sound effects is the monotonous repetition of these sounds which can be tedious to the listener. In this paper, we present a new algorithm which generates non-repetitive impact sound effects using parameters from the physical interaction. Our approach aims to use audio grains to create finely-controlled synthesized sounds which are based on recordings of impact sounds. The proposed algorithm can also be used in a large set of audio data analysis, representation, and compression applications. A subjective test was carried out to evaluate the perceptual quality of the synthesized sounds