Enabling error-resilient internet broadcasting using motion compensated spatial partitioning and packet FEC for the dirac video codec

Video transmission over the wireless or wired network require protection from channel errors since compressed video bitstreams are very sensitive to transmission errors because of the use of predictive coding and variable length coding. In this paper, a simple, low complexity and patent free error-resilient coding is proposed. It is based upon the idea of using spatial partitioning on the motion compensated residual frame without employing the transform coefficient coding. The proposed scheme is intended for open source Dirac video codec in order to enable the codec to be used for Internet broadcasting. By partitioning the wavelet transform coefficients of the motion compensated residual frame into groups and independently processing each group using arithmetic coding and Forward Error Correction (FEC), robustness to transmission errors over the packet erasure wired network could be achieved. Using the Rate Compatibles Punctured Code (RCPC) and Turbo Code (TC) as the FEC, the proposed technique provides gracefully decreasing perceptual quality over packet loss rates up to 30%. The PSNR performance is much better when compared with the conventional data partitioning only methods. Simulation results show that the use of multiple partitioning of wavelet coefficient in Dirac can achieve up to 8 dB PSNR gain over its existing un-partitioned method

Semi-hierarchical based motion estimation algorithm for the dirac video encoder

Having fast and efficient motion estimation is crucial in today’s advance video compression technique since it determines the compression efficiency and the complexity of a video encoder. In this paper, a method which we call semi-hierarchical motion estimation is proposed for the Dirac video encoder. By considering the fully hierarchical motion estimation only for a certain type of inter frame encoding, complexity of the motion estimation can be greatly reduced while maintaining the desirable accuracy. The experimental results show that the proposed algorithm gives two to three times reduction in terms of the number of SAD calculation compared with existing motion estimation algorithm of Dirac for the same motion estimation accuracy, compression efficiency and PSNR performance. Moreover, depending upon the complexity of the test sequence, the proposed algorithm has the ability to increase or decrease the search range in order to maintain the accuracy of the motion estimation to a certain level

Error-resilient performance of Dirac video codec over packet-erasure channel

Video transmission over the wireless or wired network requires error-resilient mechanism since compressed video bitstreams are sensitive to transmission errors because of the use of predictive coding and variable length coding. This paper investigates the performance of a simple and low complexity error-resilient coding scheme which combines source and channel coding to protect compressed bitstream of wavelet-based Dirac video codec in the packet-erasure channel. By partitioning the wavelet transform coefficients of the motion-compensated residual frame into groups and independently processing each group using arithmetic and Forward Error Correction (FEC) coding, Dirac could achieves the robustness to transmission errors by giving the video quality which is gracefully decreasing over a range of packet loss rates up to 30% when compared with conventional FEC only methods. Simulation results also show that the proposed scheme using multiple partitions can achieve up to 10 dB PSNR gain over its existing un-partitioned format. This paper also investigates the error-resilient performance of the proposed scheme in comparison with H.264 over packet-erasure channel

Physiology of renal glucose handling via SGLT1, SGLT2 and GLUT2.

The concentration of glucose in plasma is held within narrow limits (4-10 mmol/l), primarily to ensure fuel supply to the brain. Kidneys play a role in glucose homeostasis in the body by ensuring that glucose is not lost in the urine. Three membrane proteins are responsible for glucose reabsorption from the glomerular filtrate in the proximal tubule: sodium-glucose cotransporters SGLT1 and SGLT2, in the apical membrane, and GLUT2, a uniporter in the basolateral membrane. 'Knockout' of these transporters in mice and men results in the excretion of filtered glucose in the urine. In humans, intravenous injection of the plant glucoside phlorizin also results in excretion of the full filtered glucose load. This outcome and the finding that, in an animal model, phlorizin reversed the symptoms of diabetes, has stimulated the development and successful introduction of SGLT2 inhibitors, gliflozins, in the treatment of type 2 diabetes mellitus. Here we summarise the current state of our knowledge about the physiology of renal glucose handling and provide background to the development of SGLT2 inhibitors for type 2 diabetes treatment

The mechanisms of pedestrian slip on flooring contaminated with solid particles

Statistics by the UK Health and Safety Executive (HSE) suggest that slips, trips and falls account for up to one in three major workplace accidents. The vast majority of these accidents are the result of contaminant (fluid or solid) within the shoe-floor contact. Though the lubrication mechanisms for liquid contaminants within the contact are well understood, the same cannot be said for particulate contaminants. This paper considers the key parameters controlling friction in a shoe-floor contact contaminated with various particles of different diameters and shape factors and floors with different roughness values (Rz). Experiments were conducted using a Stanley Pendulum Tester, which is the floor friction tester recommended by the HSE. Results suggest that the adhesive friction is significantly affected by particulate contaminants, while the hysteretic component is not. Three lubrication mechanisms identified as sliding, shearing and rolling have been observed depending on floor roughness, particle size and shape factor and have been plotted in a simple map to predict behaviour

An efficient rate control algorithm for a wavelet video codec

Rate control plays an essential role in video coding and transmission to provide the best video quality at the receiver's end given the constraint of certain network conditions. In this paper, a rate control algorithm using the Quality Factor (QF) optimization method is proposed for the wavelet-based video codec and implemented on an open source Dirac video encoder. A mathematical model which we call Rate-QF (R - QF) model is derived to generate the optimum QF for the current coding frame according to the target bitrate. The proposed algorithm is a complete one pass process and does not require complex mathematical calculation. The process of calculating the QF is quite simple and further calculation is not required for each coded frame. The experimental results show that the proposed algorithm can control the bitrate precisely (within 1% of target bitrate in average). Moreover, the variation of bitrate over each Group of Pictures (GOPs) is lower than that of H.264. This is an advantage in preventing the buffer overflow and underflow for real-time multimedia data streaming

An integrated authentication and authorization approach for the network of information architecture

Several projects propose an information centric approach to the network of the future. Such an approach makes efficient content distribution possible by making information retrieval host-independent and integration into the network storage for caching information. Requests for particular content can, thus, be satisfied by any host or server holding a copy. One well-established approach of information centric networks is the Network of Information (NetInf) architecture, developed as part of the EU FP7 project SAIL. The approach is based on the Publish/Subscribe model, where hosts can join a network, publish data, and subscribe to publications. The NetInf introduces two main stages namely, the Publication and Data Retrieval through which hosts publish and retrieve data. Also, a distributed Name Resolution System (NRS) has been introduced to map the data to its publishers. The NRS is vulnerable to masquerading and content poisoning attacks through invalid data registration. Therefore, the paper proposes a Registration stage to take place before the publication and data retrieval stage. This new stage will identify and authenticate hosts before being able to access the NetInf system. Furthermore, the Registration stage uses (cap)abilities-based access policy to mitigate the issue of unauthorized access to data objects. The proposed solutions have been formally verified using formal methods approac

A formally verified access control mechanism for information centric networks

Communications in Information-Centric Networking place more attention on WHAT data are being exchanged rather than WHO are exchanging them. A well-established approach of information centric networks is the Network of Information (NetInf) architecture, developed as part of the EU FP7 project SAIL. The security of NetInf has been fairly analysed in the literature. In particular, research efforts have been focusing on achieving data integrity and confidentially, source or publisher authenticity and authorization. This paper analyses some work in the literature to enforce authorized access to data in NetInf, highlights a potential security threat and proposes an enhancement to address the discovered threat. The new enhancement has been formally verified using formal method approach based on the Casper/FDR tool

Introducing a novel authentication protocol for secure services in heterogeneous environments using Casper/FDR

Next Generation Networks is a convergence of networks such as 2G/3G, WLAN as well as the recently implemented Long Term Evolution (LTE) networks. Future mobile devices will switch between these different networks to maintain the connectivity with end servers. However, to support these heterogeneous environments, there is a need to consider a new design of the network infrastructure, where currently closed systems such as 3G will have to operate in an open environment. Security is a key issue in this open environment; after authenticating the mobile terminal to access the network, there is a requirement for service-level mechanisms to protect the session between the mobile terminal and the remote service provider. Furthermore, since mobile terminals switch between networks of different characteristics in terms of coverage, Quality of Service and security, there is a need for re-assessing the security of the same session over the different networks to comply with the changes at the network level due to the mobility. Therefore, this paper introduces a Service-Level Authentication and Key Agreement protocol to secure the session between the mobile terminal and the end server. The proposed protocol considers user mobilities in an heterogeneous environment and reassesses the session's security level in case of handover. The proposed protocol has been verified using formal methods approach based on the well-established Casper/FDR compilers

Challenges and solutions for secure information centric networks: a case study of the NetInf architecture

A large number of emerging Internet applications require information dissemination across different organizational boundaries, heterogeneous platforms, and a large, dynamic population of publishers and subscribers. A new information-centric network architecture called Network of Information (NetInf) has been developed in the context of the FP7 EU-funded 4WARD project. This architecture can significantly improve large scale information distribution. Furthermore, it supports future mobile networks in situations with intermittent and heterogeneous connectivity and connects the digital with the physical world to enable better user experience. However, NetInf is still in an early stage of implementation and its security is yet to be evaluated. The security concern of NetInf is a major factor for its wide-scale adoption. Therefore, this paper uses the X.805 security standard to analyse the security of the NetInf architecture. The analysis highlights the main source of threats and potential security services to tackle them. The paper also defines a threat model in the form of possible attacks against the NetInf architecture