Dissertação apresentada para obtenção do grau de Mestre em Redes e Serviços de Comunicação, na Faculdade de Engenharia da Universidade do Porto, sob a orientação do Professor Doutor Raúl Filipe Teixeira Oliveira

Video games are an everyday experience for adolescents and have changed how adolescents interact with one another. Prior research has focused on positive and negative aspects of video game play in general, without distinguishing Voice Over Internet Protocol (VOIPing) as the mode of play. Grounded in entertainment theory, motivational theory, and psychological distress theory, this cross-sectional, correlational study examined the relationship between VOIPing and quality of life (Pediatric Quality of Life Inventory), Yee's motivation to play video games, and resilience (Child and Youth Resilience Measure). A series of linear regression and multivariate canonical correlation models analyzed self-report responses of 103 adolescents aged 13 to18. Results indicated that VOIPing was not statistically related to quality of life or resilience. However, VOIPing correlated positively with motivation to play video games, particularly with the subscales of socialization and relationships. Canonical analysis of motivation for gaming and quality of life indicated that adolescents with high scores on customization and escapism motivation for gaming subscales tended to also have high scores on each of the emotional, social, and school quality of life subscales. Canonical analysis of motivation for gaming and resilience indicated that adolescents with low scores on the escapism motivation for gaming subscale tended to also have high scores on the individual, relationships, and community resilience subscales. The positive aspects of VOIPing, particularly with increased motivation to play video games, can be effectively used in coaching adolescents in social skills and relationship building.

<p>Voice over IP technology (VoIP) has recently gained popularity among consumers. Many popular VoIP services exist only as software for PCs. The need of taking such services out of the PC, into a stand-alone device has been discovered, and this thesis work deals with the development of such a device. The thesis work is done for Häger Scandinavia AB, a Swedish telephone manufacturer. This thesis work covers the design of a complete prototype of a table-top VoIP telephone running an embedded Linux Operating system. Design areas include product development, hardware design and software design.The result is a working prototype with hardware and corresponding Linux device drivers. The prototype can host a Linux application adapted to it. Conclusions are that the first hardware version has worked well and that using an open-source operating system is very useful. Further work consists of implementing a complete telephony software application in the system, evaluation of system requirements and adapting the prototype for a commercial design.</p>

ITC/USA 2012 Conference Proceedings / The Forty-Eighth Annual International Telemetering Conference and Technical Exhibition / October 22-25, 2012 / Town and Country Resort & Convention Center, San Diego, California / The expected efficiency of network-based telemetry systems vs. the tried and true PCM-based approaches is a debated topic. This paper chooses to use a lighthearted voice to pull the two sides of the "war" to a table of negotiation based on metrics. Ultimately, focusing on metrics that truly define efficiency is the key to understanding the varying points of view. A table of these metrics along with the "why and when" criteria for their use is presented based on historic mathematical information theory, true flight test data requirements, and lab analysis. With these metrics, the negotiation and reasonable compromises in the war may become clear. In other words, this paper attempts to provide a methodology that can be used by the community to aid in choosing the appropriate (or good enough) technologies for current and future telemetry testing demands.

Issues around Quality of Service (QoS) and security for Voice over IP (VoIP) have been extensively investigated separately, due to the great attention this technology currently attracts. The specific problem this work addresses centres upon the selection of optimal parameters for QoS and security for VoIP streams integrating both network impairments and user perception metrics into a novel empirically-driven approach. Specifically, the simulation model seeks the optimal parameters in terms of variable VoIP payloads, iterative block ciphers, codecs and authentication mechanisms to be used, so that optimum tradeoff between a set of conflicting factors is achieved. The model employs the widely used Transmission Rating Factor, R, as the methodology to predict and measure the perceived QoS based on current transmission and network impairments. The R factor is then used to map perceived QoS to the corresponding Mean Opinion Score value, which gives the average estimation of perceived voice quality (Quality of Experience). Furthermore, a genetic algorithm (GA) has been developed that uses the output from the simulation model as an input into an offline optimisation routine that simultaneously maximises the VoIP call volumes and the Level of Encryption (LoE) per call basis, without degrading the perceived quality of service under a specific threshold as dictated by the R factor. The solutions reflect the optimum combination of parameters for each codec used and due to the small size of the search space the actual speed of GA has been validated against an exhaustive search algorithm. The results extracted from this study demonstrate that under strict and pre-defined parameters the default payload size supported by the codecs is not the optimal selection in terms of call volume maximisation and perceived QoS when encryption is applied.

Voice over IP technology (VoIP) has recently gained popularity among consumers. Many popular VoIP services exist only as software for PCs. The need of taking such services out of the PC, into a stand-alone device has been discovered, and this thesis work deals with the development of such a device. The thesis work is done for Häger Scandinavia AB, a Swedish telephone manufacturer. This thesis work covers the design of a complete prototype of a table-top VoIP telephone running an embedded Linux Operating system. Design areas include product development, hardware design and software design.The result is a working prototype with hardware and corresponding Linux device drivers. The prototype can host a Linux application adapted to it. Conclusions are that the first hardware version has worked well and that using an open-source operating system is very useful. Further work consists of implementing a complete telephony software application in the system, evaluation of system requirements and adapting the prototype for a commercial design.

The situation of audiovisual translation is in its infancy in Lithuania, thus, the work specifies methods of audiovisual translation and highlights characteristic features of audiovisual-type texts. The novelty of the work lies in the investigation of the voiced-over language of the feature film. With reference to this fact, the contrastive analysis of the source language and voiced-over target language of the feature film “Bridget Jones’s Diary“was chosen as the subject of the research. The aim of the work is the examination of language and authenticity transfer of the film through voice-over as the method of audiovisual translation from English into Lithuanian. / Vertimo tyrinėtojai žengia pirmuosius žingsnius audiovizualiojo vertimo tyrinėjimo srityje, nors įgarsintus, subtitruotus ar jau ir dubliuotus filmus žiūrime kasdien per televiziją ar kino teatre. Naujosios technologijos leidžia vos panorėjus mėgautis filmais, kurie atlieka ne tik pramoginę, bet ir kitos kultūros pažinimo funkciją. Didžioji dalis į Lietuvą atkeliaujančių filmų yra anglų kalba. Juos įprasta įgarsinti. Tačiau dėl įvairių priežasčių ne visada lietuviškame filmo variante išgirstame tai, kas buvo pasakyta originale. Šio darbo tikslas – išnagrinėti gerai žinomo vaidybinio filmo „Bridžitos Džouns dienoraštis“ kalbos ir autentikos perteikimą per įgarsintą filmo vertimą, siekiant nustatyti vertimo procese naudojamas vertimo procedūras. Mokslinio darbo teorinėje dalyje išsamiai pristatomi audiovizualaus vertimo metodai, apžvelgiami audiovizualaus teksto ypatumai, jame slypintys kodai bei paaiškinama domestikacijos samprata. Empirinėje darbo dalyje aprašoma tyrimo eiga ir analizuojami rezultatai. Filmo vertimo tyrimas atskleidė, jog dėl pačių kalbų (anglų ir lietuvių) skirtumų, tokių vertimo procedūrų kaip glaudinimas, eliminavimas ir trumpinimas naudojimas bei vertėjo(s) klaidos lėmė prasminius vertimo kalbos nuostolius. Nors vertėja(s) didžiajai teksto daliai rado atitinkamus ekvivalentus bei daugelyje atvejų pasitelkė parafrazę ir plėtimą, vertimo kalba perteikta glausčiau dėl aukščiau minėtų veiksnių bei filmo vertimo metodo ypatumų.

Learner engagement has been considered one of the keys that can lead learners to successful learning in a multimedia learning environment such as digital game-based learning. Regarding this point, game-based learning advocates (e.g., Gee, 2003; Prensky, 2001) have asserted that digital games have great potential to engage learners. Nonetheless, there have been only a small number of empirical research studies of players' engagement, and there is little consensus on which elements of digital games critically engage people in play (Garris, Ahlers, & Driskell, 2002). Furthermore, despite the possibility that sensory stimuli can be factors influencing digital game players' engagement, there have been very few attempts to examine empirically the relationship between engagement and sensory stimuli. This study examined the effects of game characters' voice-over in digital games on players' engagement, by using a short digital role-playing game modified from Neverwinter Nights 2. A randomized control-group post-test only design was used to collect data from 74 participants (22 female, 52 male); engagement was measured by a modification of the Game Engagement Questionnaire (Brockmyer et al., 2009). Data analysis revealed that the GEQ mean scores of the participants who played the game with voice-over was much higher than that of the participants who played without voice-over. The difference of the mean scores between the two groups was statistically significant (t = 2.45, df = 72 p = .02), and the effect size, Cohen's d, was .58 (moderately significant). The results of this study will guide educational practitioners to the identification of more effective ways of adopting, developing, and modifying digital games for educational purposes, as well as furthering the research and guiding the practice in instructional multimedia design and development.

This thesis reviews the usual properties and requirements for key agreement protocols. It then focuses on MIKEY, a work-in-progress protocol designed to conduct key agreements for secure multimedia exchanges. The protocol was implemented and incorporated in a SIP user agent - minisip. This implementation was used to measure the additional delay required for key exchange during call establishment. Finally, some schemes are proposed regarding the use of MIKEY in advanced VoIP scenarios, such as conferences and terminal mobility.

Voice over IP (VoIP) is a relatively new technology that enables voice calls over data networks.With VoIP it is possible to lower expenses, and increase functionality and flexibility. FromSwedish Armed Forces point of view, the security issue is of great importance, why the focus inthis report is on the security aspect of the two most common open-source VoIP-protocols H.323and SIP, some of the most common attacks, and counter-measures for those attacks.Because of the level of complexity with a network running H.323 or SIP, and the fact that it hasyet to stand the same level of trial as of traditional telephony, a VoIP-system includes manyknown security-issues, and probably at present many unknown security flaws. The conclusion is that it takes great knowledge and insight about a VoIP-network based onH.323 or SIP to make the network satisfyingly safe as it is today, and is therefore perhaps not asuitable solution for the Swedish Armed Forces today for their more sensitive communications. / Voice over IP (VoIP) är en datakommunkationsteknik som möjliggör röstsamtal överdatanätverk. Med VoIP är det möjligt att sänka kostnader, utöka funktionalitet och flexibilitet.Från Försvarsmaktens perspektiv är säkerhetsfrågan med VoIP av stor vikt, därför läggs speciellfokus för denna rapport på säkerhetsaspekten av de två största öppna VoIP-protokollen H.323och SIP, några av de vanligaste attackerna, och åtgärder mot dessa attacker. Eftersom uppbyggnaden av ett H.323- eller SIP-baserat nätverk är komplext och inte allsbeprövat i samma utsträckning som traditionell telefoni, innehåller det många kända säkerhetshåloch förmodligen för närvarande många okända säkerhetsbrister. Slutsatsen är att det krävs mycket stor kunskap och insikt hur ett VoIP-nätverk baserat på H.323eller SIP fungerar för att göra nätverket tillräckligt säkert i nuläget, vilket gör det till en tveksamttillfredställande lösning för Försvarsmakten idag för deras kommunikation av känsligare slag.