Automatic real-time transcription of multimedia conference

Cílem práce je řešení pro přepis multimediální konference založené na protokolu WebRTC v reálném čase za pomoci kombinace existujících technologií a řešení v oblasti konferencí, přenosu médií a rozpoznávání řeči. Aplikace je naprogramována v Javě. Pro signalizaci se používá protokol WebSocket a pro přenos audio dat protokol RTP. Součástí řešení je modulární transkripční back-end využívající rozhraní Google Cloud Speech-to-text API a řešení pro rozpoznávání řeči vyvinuté v Laboratoři počítačového zpracování řeči (SpeechLab) na Technické univerzitě v Liberci. Přepisy jsou zobrazeny v prohlížečích účastníků v reálném čase a zároveň jsou zapisovány do souboru. Práce obsahuje příklady přepisovaných konverzací.This work focuses on performing real-time transcription of a multimedia conference based on WebRTC protocol by combining existing technologies and solutions in conferencing, media transmission and speech recognition in one application. The result application is written in Java. It uses WebSocket to communicate with a conferencing application, RTP for receiving audio data and suggests modular transcription back-ends with Google Cloud Speech-to-text API and speech recognition engine developed by the Laboratory of Computer Speech Processing (SpeechLab) in Technical University of Liberec already successfully integrated. Transcripts are stored in files and also can be displayed in browsers in real-time. Examples of transcribed conversations are provided

Integrated Home Server

Since the advent of the microprocessor in the 1970s, the market for consumer electronics has exploded with new devices changing the way we live and do business. Today, mobile phones, cameras, PCs, iPads, mp3 players, network media players, security systems, automation and IT systems, all have common functionality and there is an increasing need for unification of access to all these devices around a common server based architecture to unlock the benefits of smart integration and to simplify access for the end user. IHS project is designed to provide to its business and home owners a unified network for all IT and electronic systems within a home or an office. This system integrates security, surveillance, access and attendance, home automation, audio and video players, File Server, Email Server, SMS Server (Texting), HTTP Proxy Server, DHCP Server, a caching DNS Server, Web Server and an internet gateway with an automatic virus scanner. In fact, it is a comprehensive system that completely governs a place wherever it is installed and provides integrated remotely accessible infrastructure for a Home or Business. Access to all home and business systems is available from any computer on the LAN, the internet and mobile phone. IHS is built around the Gateman Lifestyle Server which uses the robust Enterprise Linux Kernel CEntOS 5 and is written in Java. It can be accessed from Windows, MAC, Linux machines and i-phones as well as from any device that has a Java script enabled web browser. The device driver architecture allows additional electronic hardware to be incorporated making it relevant and extendable well into the future

Expressions and embeddings of deliberative democracy in mutual benefit digital goods

Since democracy is so desirable and digital technologies are so flexible and widespread it is worth asking what sort of digital technologies can, through use, enhance democratic practice. This question is addressed in three stages. First, the notion of Mutual Benefit Digital Goods (MBDGs) is developed as a tool for discerning the digital goods that hold a potential for nurturing democratic virtues. MBDGs are those digital goods that allow a user to make such goods one’s own and to put something of oneself into them. This can be achieved either directly, by working at creating a derivative of a digital good, or by engaging a community of production for digital goods. The second stage is the identification of a theory of democracy that is adequate for discussing democracy in relation to cyberspace. Deliberative democracy, particularly as presented by Dryzek, is put forward as the most appropriate conception of democracy to be used. This conception makes it possible to overcome the difficulties posed by the notions of citizens and borders as presented in other conceptions of democracy. In relation to cyberspace, such notions are particularly problematic. In the last stage, MBDGs and deliberative democracy are brought together by means of the theory of technological mediation and Feenberg's theory of technological subversion. The theory of mediation holds that the use of technologies modulates our moral landscape. Because of mediation, subversion of digital technologies is always self-expressive to some extent. Therefore it exhibits the same grounding characteristics as deliberative democracy: mutual respect, reciprocity, provisionality and equality. Since MBDGs are most open to subversion, they are also the digital technologies with the most potential for fostering democracy. This claim is corroborated by looking at iconic MBDGs (Free/ Libre/ Open Source Software and Wikipedia) and revealing how the virtues necessary for deliberation are manifest in some of the activities surrounding these digital goods. The ideas presented, if accepted, have practical implications for institutions desirous of enhancing democratic practice. Such institutions ought to evaluate their choices on digital technologies also on grounds of democratic potential, reduce obstacles to alternative appropriation of digital goods through regulation, and foster MBDGs

Audio/Video Transmission over IEEE 802.11e Networks: Retry Limit Adaptation and Distortion Estimation

The objective of this thesis focuses on the audio and video transmission over wireless networks adopting the family of the IEEE 802.11x standards. In particular, this thesis discusses about the resolution of four issues: the adaptive retransmission, the comparison of video quality indexes for retry limit adaptation purposes, the estimation of the distortion and the joint adaptation of the maximum number of retransmissions of voice and video flows

Customer premise service study for 30/20 GHz satellite system

Satellite systems in which the space segment operates in the 30/20 GHz frequency band are defined and compared as to their potential for providing various types of communications services to customer premises and the economic and technical feasibility of doing so. Technical tasks performed include: market postulation, definition of the ground segment, definition of the space segment, definition of the integrated satellite system, service costs for satellite systems, sensitivity analysis, and critical technology. Based on an analysis of market data, a sufficiently large market for services is projected so as to make the system economically viable. A large market, and hence a high capacity satellite system, is found to be necessary to minimize service costs, i.e., economy of scale is found to hold. The wide bandwidth expected to be available in the 30/20 GHz band, along with frequency reuse which further increases the effective system bandwidth, makes possible the high capacity system. Extensive ground networking is required in most systems to both connect users into the system and to interconnect Earth stations to provide spatial diversity. Earth station spatial diversity is found to be a cost effective means of compensating the large fading encountered in the 30/20 GHz operating band

Diseño centrado en calidad para la difusión Peer-to-Peer de video en vivo

El uso de redes Peer-to-Peer (P2P) es una forma escalable para ofrecer servicios de video sobre Internet. Este documento hace foco en la definición, desarrollo y evaluación de una arquitectura P2P para distribuir video en vivo. El diseño global de la red es guiado por la calidad de experiencia (Quality of Experience - QoE), cuyo principal componente en este caso es la calidad del video percibida por los usuarios finales, en lugar del tradicional diseño basado en la calidad de servicio (Quality of Service - QoE) de la mayoría de los sistemas. Para medir la calidad percibida del video, en tiempo real y automáticamente, extendimos la recientemente propuesta metodología Pseudo-Subjective Quality Assessment (PSQA). Dos grandes líneas de investigación son desarrolladas. Primero, proponemos una técnica de distribución de video desde múltiples fuentes con las características de poder ser optimizada para maximizar la calidad percibida en contextos de muchas fallas y de poseer muy baja señalización (a diferencia de los sistemas existentes). Desarrollamos una metodología, basada en PSQA, que nos permite un control fino sobre la forma en que la señal de video es dividida en partes y la cantidad de redundancia agregada, como una función de la dinámica de los usuarios de la red. De esta forma es posible mejorar la robustez del sistema tanto como sea deseado, contemplando el límite de capacidad en la comunicación. En segundo lugar, presentamos un mecanismo estructurado para controlar la topología de la red. La selección de que usuarios servirán a que otros es importante para la robustez de la red, especialmente cuando los usuarios son heterogéneos en sus capacidades y en sus tiempos de conexión.Nuestro diseño maximiza la calidad global esperada (evaluada usando PSQA), seleccionado una topología que mejora la robustez del sistema. Además estudiamos como extender la red con dos servicios complementarios: el video bajo demanda (Video on Demand - VoD) y el servicio MyTV. El desafío en estos servicios es como realizar búsquedas eficientes sobre la librería de videos, dado al alto dinamismo del contenido. Presentamos una estrategia de "caching" para las búsquedas en estos servicios, que maximiza el número total de respuestas correctas a las consultas, considerando una dinámica particular en los contenidos y restricciones de ancho de banda. Nuestro diseño global considera escenarios reales, donde los casos de prueba y los parámetros de configuración surgen de datos reales de un servicio de referencia en producción. Nuestro prototipo es completamente funcional, de uso gratuito, y basado en tecnologías bien probadas de código abierto

Interdomain User Authentication and Privacy

This thesis looks at the issue of interdomain user authentication, i.e. user authentication in systems that extend over more than one administrative domain. It is divided into three parts. After a brief overview of related literature, the first part provides a taxonomy of current approaches to the problem. The taxonomy is first used to identify the relative strengths and weaknesses of each approach, and then employed as the basis for putting into context four concrete and novel schemes that are subsequently proposed in this part of the thesis. Three of these schemes build on existing technology; the first on 2nd and 3rd-generation cellular (mobile) telephony, the second on credit/debit smartcards, and the third on Trusted Computing. The fourth scheme is, in certain ways, different from the others. Most notably, unlike the other three schemes, it does not require the user to possess tamper-resistant hardware, and it is suitable for use from an untrusted access device. An implementation of the latter scheme (which works as a web proxy) is also described in this part of the thesis. As the need to preserve one’s privacy continues to gain importance in the digital world, it is important to enhance user authentication schemes with properties that enable users to remain anonymous (yet authenticated). In the second part of the thesis, anonymous credential systems are identified as a tool that can be used to achieve this goal. A formal model that captures relevant security and privacy notions for such systems is proposed. From this model, it is evident that there exist certain inherent limits to the privacy that such systems can offer. These are examined in more detail, and a scheme is proposed that mitigates the exposure to certain attacks that exploit these limits in order to compromise user privacy. The second part of the thesis also shows how to use an anonymous credential system in order to facilitate what we call ‘privacy-aware single sign-on’ in an open environment. The scheme enables the user to authenticate himself to service providers under separate identifier, where these identifiers cannot be linked to each other, even if all service providers collude. It is demonstrated that the anonymity enhancement scheme proposed earlier is particularly suited in this special application of anonymous credential systems. Finally, the third part of the thesis concludes with some open research questions

Techniques for the Analysis of Modern Web Page Traffic using Anonymized TCP/IP Headers

Analysis of traces of network traffic is a methodology that has been widely adopted for studying the Web for several decades. However, due to recent privacy legislation and increasing adoption of traffic encryption, often only anonymized TCP/IP headers are accessible in traffic traces. For traffic traces to remain useful for analysis, techniques must be developed to glean insight using this limited header information. This dissertation evaluates approaches for classifying individual web page downloads — referred to as web page classification — when only anonymized TCP/IP headers are available. The context in which web page classification is defined and evaluated in this dissertation is different from prior traffic classification methods in three ways. First, the impact of diversity in client platforms (browsers, operating systems, device type, and vantage point) on network traffic is explicitly considered. Second, the challenge of overlapping traffic from multiple web pages is explicitly considered and demultiplexing approaches are evaluated (web page segmentation). And lastly, unlike prior work on traffic classification, four orthogonal labeling schemes are considered (genre-based, device-based, navigation-based, and video streaming-based) — these are of value in several web-related applications, including privacy analysis, user behavior modeling, traffic forecasting, and potentially behavioral ad-targeting. We conduct evaluations using large collections of both synthetically generated data, as well as browsing data from real users. Our analysis shows that the client platform choice has a statistically significant impact on web traffic. It also shows that change point detection methods, a new class of segmentation approach, outperform existing idle time-based methods. Overall, this work establishes that web page classification performance can be improved by: (i) incorporating client platform differences in the feature selection and training methodology, and (ii) utilizing better performing web page segmentation approaches. This research increases the overall awareness on the challenges associated with the analysis of modern web traffic. It shows and advocates for considering real-world factors, such as client platform diversity and overlapping traffic from multiple streams, when developing and evaluating traffic analysis techniques.Doctor of Philosoph