Tomáš Rebok

High-definition multimedia for multiparty low-latency interactive communication

We describe a high-quality collaborative environment that uses High-Definition (HD) video to achieve near realistic perception of a remote site. The capture part, consisting of a HD camera, Centaurus HD-SDI capture card, and UltraGrid software, produces a 1.5 Gbps UDP data stream of uncompressed HD video that is transferred over a 10GE network interface to the high-speed IP network. The HD video stream displaying uses either a software-based solution with color depth down-sampling and field de-interlacing, or another Centaurus card. Data distribution to individual participants of the videoconference is achieved using a user-controlled UDP packet reflector based on the Active Element idea. The viability of this system has been demonstrated at the iGrid 2005 conference for a three-way high quality videoconference among sites in the Czech Republic, Louisiana, and California.

Cloud-based testbed for simulation of cyber attacks

Cyber attacks have become ubiquitous and in order to face current threats it is important to understand them. Studying attacks in a real environment however, is not viable and therefore it is necessary to find other methods how to examine the nature of attacks. Gaining detailed knowledge about them facilitates designing of new detection methods as well as understanding their impact. In this paper we present a testbed framework to simulate attacks that enables to study a wide range of security scenarios. The framework provides a notion of real-world arrangements, yet it retains full control over all the activities performed within the simulated infrastructures. Utilizing the sandbox environment, it is possible to simulate various security attacks and evaluate their impacts on real infrastructures. The design of the framework benefits from IaaS clouds. Therefore its deployment does not require dedicated facilities and the testbed can be deployed over miscellaneous contemporary clouds. The viability of the testbed has been verified by a simulation of particular DDoS attack.

DiProNN: VM-Based Distributed Programmable Network Node Architecture

The programmable network approach allows processing of passing user data in a network, which is highly suitable especially for video streams processing. However, the programming of complex stream processing applications for programmable nodes is not effortless, since the applications usually do not provide sufficient flexibility (both programming flexibility and execution environment flexibility). In this paper we present the architecture of our DiProNN node—the VM-based Distributed Programmable Network Node, that is able to accept and run user-supplied programs and/or virtual machines and process them (in parallel if requested) over passing user data. The node is primarily meant to perform stream processing; to enhance DiProNN flexibility and make programming of streaming applications for a DiProNN node easier, we also propose a suitable modular programming model which takes advantage of DiProNN’s virtualization and makes its programming more comfortable.

DiProNN: Distributed Programmable Network Node Architecture

The programmable network approach allows processing of passing user data in a network, which is highly suitable especially for multimedia streams processing. However, programming of complex stream processing applications for programmable nodes is not effortless since they usually do not provide sufficient flexibility (both programming flexibility and execution environment flexibility). In this paper we present the programmable network node architecture named DiProNN that is able to accept and run user-supplied programs and/or virtual machines and process them over passing data. All the DiProNN programs are described using our modular programming model based on the workflow principles that takes advantages of DiProNN virtualization and makes programming of complex streaming applications easier. As a possible application we show a sketch implementation of simple MCU (Multipoint Control Unit) used for large videoconferences that profits from DiProNN properties.

Stereoscopic Video over IP Networks

Transfers of high-quality multimedia content pose new demands on capacity and services provided by the contemporary high-speed computer networks. Transfer of stereoscopic video is a specific example, as it needs synchronization between two separate data streams. We have set up a stereoscopic video capture system and studied synchronization of two separate digital video format streams sent over packet networks. We have adapted application tools to support the synchronization and used an active element working as a synchronizing UDP packet reflector to explicitly synchronize the streams if they are desynchronized in the network. We have experimentally studied the quality of achievable synchronization and the relationship between the amount of desynchronization and the additional latency overhead posed by buffering of the data on the synchronizing reflector. The results prove our assumption that even high-quality DV streams can be successfully synchronized using the simple packet reflector running on common IA32-based computer

Ruby benchmark tool using docker

The purpose of this paper is to introduce and describe a new Ruby benchmarking tool. We will describe the background of Ruby benchmarking and the advantages of the new tool. The paper documents the benchmarking process as well as methods used to obtain results and run tests. To illustrate the provided tool, results that were obtained by running a developed benchmarking tool on existing and available official ruby benchmarks are provided. These results document advantages in using various Ruby compilers or Ruby implementations.