190 research outputs found
Linux-Box: DVB and VoD streaming over local area networks
Aquest treball tracta sobre un projecte comú anomenat Linux-Box portat a terme per diferents persones al departament de Telecomunicacions (IET) de la Universitat de Pisa. Linux-Box és un sistema dotat amb targetes TDT (DVB-T) i de televisió per satèl·lit (DVB-S) que permet transmetre aquests senyals fins a un à mbit domèstic. Més endavant podria ser utilitzat en à mbits privats com les cases de clients o en institucions públiques com escoles, universitats, biblioteques i també seria possible en à mbits empresarials. El projecte està dividit en 4 apartats:
1. Ubuntu 6.06 LTS. Explica perquè s’utilitza Ubuntu en el projecte. A més
també s’explica de forma breu que és Linux i les distribucions més utilitzades.
2. Multimedia Network Protocols: s’expliquen els diferents protocols desde la capa de xarxa fins la capa d’aplicació que s’utilitzen en el projecte Linux-Box.
Aquests protocols sĂłn utilitzats tant en streaming, com en anunciaciĂł,
unicast/multicast, encapsulat de vĂdeo i codecs. Els diversos temes tractats aquĂ
es fan amb el propòsit de comparar i no només com a recerca teòrica. A la fi es
veuen els programes utilitzats en el projecte per analitzar el trĂ fic de la xarxa.
3. Linux-Box: s’explica el funcionament i els objectius globals del projecte. Es
dedica un sub-apartat a “VideoLan - VLC” part important a nivell de sofware. Més
endavant es parla de les caracterĂstiques de la Linux-Box de forma acurada:
streaming de VoD i senyals de TV i s’analitzen els problemes coneguts i les
seves solucions proposades. A la fi s’enumeren els llenguatges de programació
utilitzats al projecte i en quina part s’utilitzen. Observarem que és una aplicació
on diversos llenguatges de programaciĂł estan contĂnuament solapats.
4. Developed Part: es posa en prĂ ctica la teoria estudiada a la resta del treball.
EstĂ dividida en 4 seccions:
Desenvolupar una aplicaciĂł en codi C per convertir la llista de Canals
(tant terrestre com de satèl·lit) en format XML.
Una secciĂł dedicada al streaming de Canals de TV a la pĂ gina web principal.
Un anĂ lisis profund dels paquets creats per la Linux-Box i la seva activitat a la xarxa.
Finalment s’analitzen els diferents scripts i les seves configuracions.
Alguns són útils per a un futur desenvolupament i d’altres s’utilitzen en
seccions prèvies.
5. Conclusions: contĂ© les conclusions i lĂnies futures. El projecte compta amb
diverses opcions que encara poden ser implementades i estudiades. AquĂ
exposem les nostres interpretacions i possibles lĂnies futures d’estudi
Linux-Box: DVB and VoD streaming over local area networks
Aquest treball tracta sobre un projecte comú anomenat Linux-Box portat a terme per diferents persones al departament de Telecomunicacions (IET) de la Universitat de Pisa. Linux-Box és un sistema dotat amb targetes TDT (DVB-T) i de televisió per satèl·lit (DVB-S) que permet transmetre aquests senyals fins a un à mbit domèstic. Més endavant podria ser utilitzat en à mbits privats com les cases de clients o en institucions públiques com escoles, universitats, biblioteques i també seria possible en à mbits empresarials. El projecte està dividit en 4 apartats:
1. Ubuntu 6.06 LTS. Explica perquè s’utilitza Ubuntu en el projecte. A més
també s’explica de forma breu que és Linux i les distribucions més utilitzades.
2. Multimedia Network Protocols: s’expliquen els diferents protocols desde la capa de xarxa fins la capa d’aplicació que s’utilitzen en el projecte Linux-Box.
Aquests protocols sĂłn utilitzats tant en streaming, com en anunciaciĂł,
unicast/multicast, encapsulat de vĂdeo i codecs. Els diversos temes tractats aquĂ
es fan amb el propòsit de comparar i no només com a recerca teòrica. A la fi es
veuen els programes utilitzats en el projecte per analitzar el trĂ fic de la xarxa.
3. Linux-Box: s’explica el funcionament i els objectius globals del projecte. Es
dedica un sub-apartat a “VideoLan - VLC” part important a nivell de sofware. Més
endavant es parla de les caracterĂstiques de la Linux-Box de forma acurada:
streaming de VoD i senyals de TV i s’analitzen els problemes coneguts i les
seves solucions proposades. A la fi s’enumeren els llenguatges de programació
utilitzats al projecte i en quina part s’utilitzen. Observarem que és una aplicació
on diversos llenguatges de programaciĂł estan contĂnuament solapats.
4. Developed Part: es posa en prĂ ctica la teoria estudiada a la resta del treball.
EstĂ dividida en 4 seccions:
ď‚· Desenvolupar una aplicaciĂł en codi C per convertir la llista de Canals
(tant terrestre com de satèl·lit) en format XML.
ď‚· Una secciĂł dedicada al streaming de Canals de TV a la pĂ gina web principal.
ď‚· Un anĂ lisis profund dels paquets creats per la Linux-Box i la seva activitat a la xarxa.
 Finalment s’analitzen els diferents scripts i les seves configuracions.
Alguns són útils per a un futur desenvolupament i d’altres s’utilitzen en
seccions prèvies.
5. Conclusions: contĂ© les conclusions i lĂnies futures. El projecte compta amb
diverses opcions que encara poden ser implementades i estudiades. AquĂ
exposem les nostres interpretacions i possibles lĂnies futures d’estudi
TORKAMELEON. IMPROVING TOR’S CENSORSHIP RESISTANCE WITH K-ANONYMIZATION MEDIA MORPHING COVERT INPUT CHANNELS
Anonymity networks such as Tor and other related tools are powerful means of increas-
ing the anonymity and privacy of Internet users’ communications. Tor is currently the
most widely used solution by whistleblowers to disclose confidential information and
denounce censorship measures, including violations of civil rights, freedom of expres-
sion, or guarantees of free access to information. However, recent research studies have
shown that Tor is vulnerable to so-called powerful correlation attacks carried out by
global adversaries or collaborative Internet censorship parties. In the Tor ”arms race”
scenario, we can see that as new censorship, surveillance, and deep correlation tools have
been researched, new, improved solutions for preserving anonymity have also emerged.
In recent research proposals, unobservable encapsulation of IP packets in covert media
channels is one of the most promising defenses against such threat models. They leverage
WebRTC-based covert channels as a robust and practical approach against powerful traf-
fic correlation analysis. At the same time, these solutions are difficult to combat through
the traffic-blocking measures commonly used by censorship authorities.
In this dissertation, we propose TorKameleon, a censorship evasion solution de-
signed to protect Tor users with increased censorship resistance against powerful traffic
correlation attacks executed by global adversaries. The system is based on flexible K-
anonymization input circuits that can support TLS tunneling and WebRTC-based covert
channels before forwarding users’ original input traffic to the Tor network. Our goal
is to protect users from machine and deep learning correlation attacks between incom-
ing user traffic and observed traffic at different Tor network relays, such as middle and
egress relays. TorKameleon is the first system to implement a Tor pluggable transport
based on parameterizable TLS tunneling and WebRTC-based covert channels. We have
implemented the TorKameleon prototype and performed extensive validations to ob-
serve the correctness and experimental performance of the proposed solution in the Tor
environment. With these evaluations, we analyze the necessary tradeoffs between the
performance of the standard Tor network and the achieved effectiveness and performance
of TorKameleon, capable of preserving the required unobservability properties.Redes de anonimização como o Tor e soluções ou ferramentas semelhantes são meios
poderosos de aumentar a anonimidade e a privacidade das comunicações de utilizadores
da Internet . O Tor Ă© atualmente a rede de anonimato mais utilizada por delatores para
divulgar informações confidenciais e denunciar medidas de censura tais como violações
de direitos civis e da liberdade de expressĂŁo, ou falhas nas garantias de livre acesso Ă
informação. No entanto, estudos recentes mostram que o Tor é vulnerável a adversários
globais ou a entidades que colaboram entre si para garantir a censura online. Neste
cenário competitivo e de jogo do “gato e do rato”, Ă© possĂvel verificar que Ă medida que
novas soluções de censura e vigilância são investigadas, novos sistemas melhorados para
a preservação de anonimato são também apresentados e refinados. O encapsulamento de
pacotes IP em tĂşneis encapsulados em protocolos de media sĂŁo uma das mais promissoras
soluções contra os novos modelos de ataque à anonimidade. Estas soluções alavancam
canais encobertos em protocolos de media baseados em WebRTC para resistir a poderosos
ataques de correlação de tráfego e a medidas de bloqueios normalmente usadas pelos
censores.
Nesta dissertação propomos o TorKameleon, uma solução desenhada para protoger
os utilizadores da rede Tor contra os mais recentes ataques de correlação feitos por um
modelo de adversário global. O sistema é baseado em estratégias de anonimização e
reencaminhamento do tráfego do utilizador através de K nós, utilizando também encap-
sulamento do tráfego em canais encobertos em túneis TLS ou WebRTC. O nosso objetivo
é proteger os utilizadores da rede Tor de ataques de correlação implementados através
de modelos de aprendizagem automática feitos entre o tráfego do utilizador que entra
na rede Tor e esse mesmo tráfego noutro segmento da rede, como por exemplo nos nós
de saĂda da rede. O TorKameleon Ă© o primeiro sistema a implementar um Tor pluggable
transport parametrizável, baseado em túneis TLS ou em canais encobertos em protocolos
media. Implementamos um protótipo do sistema e realizamos uma extensa avalição expe-
rimental, inserindo a solução no ambiente da rede Tor. Com base nestas avaliações, anali-
zamos o tradeoff necessário entre a performance da rede Tor e a eficácia e a performance
obtida do TorKameleon, que garante as propriedades de preservação de anonimato
Test bed design for interactive video conference services
In the last decade, telecommunication industry has been widely developed in area
of the multimedia interactive services. Actually, there are still emerging new videoconference
and instant messaging applications.
For the provisioning of multimedia interactive services it is essential to provide
a required level of customer satisfaction, given by the end-user quality. The
video and audio compression improvement of the newest video coding standards
H.264/AVC and AAC allows for providing video and audio streaming for low bit
and frame rates while preserving the perceptual quality. This is especially suitable
for interactive multimedia applications in 3G wireless networks.
The aim of this thesis was to design the ”State of the Art” video conferencing
environment supporting H.264/AVC and AAC codecs. Moreover, this environment
provides opportunity to analyze end user quality at all layer of OSI model.
As a result of this design, we have an open source application, that offers a good
quality of image and sound at very low rates (90kbps, 9fps for video) at the same
time that reduces the reception delay that now exists in commercial applications
EVEREST IST - 2002 - 00185 : D23 : final report
Deliverable pĂşblic del projecte europeu EVERESTThis deliverable constitutes the final report of the project IST-2002-001858 EVEREST. After its successful completion, the project presents this document that firstly summarizes the context, goal and the approach objective of the project. Then it presents a concise summary of the major goals and results, as well as highlights the most valuable lessons derived form the project work. A list of deliverables and publications is included in the annex.Postprint (published version
Recommended from our members
Multimedia delivery in the future internet
The term “Networked Media” implies that all kinds of media including text, image, 3D graphics, audio
and video are produced, distributed, shared, managed and consumed on-line through various networks,
like the Internet, Fiber, WiFi, WiMAX, GPRS, 3G and so on, in a convergent manner [1]. This white
paper is the contribution of the Media Delivery Platform (MDP) cluster and aims to cover the Networked
challenges of the Networked Media in the transition to the Future of the Internet.
Internet has evolved and changed the way we work and live. End users of the Internet have been confronted
with a bewildering range of media, services and applications and of technological innovations concerning
media formats, wireless networks, terminal types and capabilities. And there is little evidence that the pace
of this innovation is slowing. Today, over one billion of users access the Internet on regular basis, more
than 100 million users have downloaded at least one (multi)media file and over 47 millions of them do so
regularly, searching in more than 160 Exabytes1 of content. In the near future these numbers are expected
to exponentially rise. It is expected that the Internet content will be increased by at least a factor of 6, rising
to more than 990 Exabytes before 2012, fuelled mainly by the users themselves. Moreover, it is envisaged
that in a near- to mid-term future, the Internet will provide the means to share and distribute (new)
multimedia content and services with superior quality and striking flexibility, in a trusted and personalized
way, improving citizens’ quality of life, working conditions, edutainment and safety.
In this evolving environment, new transport protocols, new multimedia encoding schemes, cross-layer inthe
network adaptation, machine-to-machine communication (including RFIDs), rich 3D content as well as
community networks and the use of peer-to-peer (P2P) overlays are expected to generate new models of
interaction and cooperation, and be able to support enhanced perceived quality-of-experience (PQoE) and
innovative applications “on the move”, like virtual collaboration environments, personalised services/
media, virtual sport groups, on-line gaming, edutainment. In this context, the interaction with content
combined with interactive/multimedia search capabilities across distributed repositories, opportunistic P2P
networks and the dynamic adaptation to the characteristics of diverse mobile terminals are expected to
contribute towards such a vision.
Based on work that has taken place in a number of EC co-funded projects, in Framework Program 6 (FP6)
and Framework Program 7 (FP7), a group of experts and technology visionaries have voluntarily
contributed in this white paper aiming to describe the status, the state-of-the art, the challenges and the way
ahead in the area of Content Aware media delivery platforms
QoE de streaming de vĂdeo em redes veiculares com multihoming
With the ever-increasing interest and availability of vehicular networks, it is important
to study the Quality-of-Experience provided by these networks, which
ultimately determines the general public perception and thus the overall user
adoption. The broad Internet access, the evolution of user equipment, such
as smartphones, tablets and personal computers, and the appearance of services
like Youtube and Netflix, is leading the user content consumption to be
more and more in the form of video streaming. Either motivated by safety or
commercial applications, video streaming in such highly mobile environments
offers multiple challenges.
This dissertation evaluates the QoE of a multihoming communication strategy,
supported simultaneously byWAVE and Wi-Fi, for increasing the reliability and
performance of video streams in these environments. Furthermore, it also investigates
how distinct network functionalities, such as multihoming load balance,
buffering, and network metrics such as throughput and latency affect the
overall QoE observed. The results obtained led to the proposal of a multihoming
load balance policy for video applications based on access technologies,
aiming to improve QoE. The overall results show that QoE improves by 7.5%
using the proposed approach.Com o aumento contĂnuo do interesse e disponibilidade de redes veiculares,
Ă© importante agora estudar a Qualidade de ExperiĂŞncia fornecida por estas
redes, que fundamentalmente determina a opinião e a percepção do público
geral sobre um dado serviço. O vasto acesso à Internet, a evolução dos equipamentos,
como os telemĂłveis atuais, tablets e computadores pessoais, e o
aparecimento de serviços como o YouTube e o Netflix, está a fazer com que
o conteĂşdo mais consumido seja cada vez mais em forma de streaming de
vĂdeo. Quer seja motivado por aplicações de segurança ou comerciais, o streaming
de vĂdeo em ambientes altamente mĂłveis levanta vários desafios.
Esta dissertação avalia a Qualidade de Experiência de técnicas de multihoming,
permitindo o uso de diferentes tecnologias de comunicação, como o
WAVE e o Wi-Fi, para aumentar a fiabilidade e desempenho de streams de
vĂdeo nestes ambientes. Para alĂ©m disso, investiga tambĂ©m como Ă© que diferentes
mecanismos de rede, como o balanceamento, multihoming e o buffering,
e métricas como a taxa de transferência e latência, afetam a QoE observada.
Os resultados obtidos levaram Ă proposta de uma polĂtica de divisĂŁo
de tráfego para aplicações de vĂdeo baseada em tecnologias de acesso
para situações de multihoming, visando uma melhoria da QoE do utilizador.
Utilizando o método proposto, os resultados mostram que a experiência do
utilizador tem uma melhoria de 7,5%.Mestrado em Engenharia de Computadores e Telemátic
Video QoS/QoE over IEEE802.11n/ac: A Contemporary Survey
The demand for video applications over wireless networks has tremendously increased, and IEEE 802.11 standards have provided higher support for video transmission. However, providing Quality of Service (QoS) and Quality of Experience (QoE) for video over WLAN is still a challenge due to the error sensitivity of compressed video and dynamic channels. This thesis presents a contemporary survey study on video QoS/QoE over WLAN issues and solutions. The objective of the study is to provide an overview of the issues by conducting a background study on the video codecs and their features and characteristics, followed by studying QoS and QoE support in IEEE 802.11 standards. Since IEEE 802.11n is the current standard that is mostly deployed worldwide and IEEE 802.11ac is the upcoming standard, this survey study aims to investigate the most recent video QoS/QoE solutions based on these two standards. The solutions are divided into two broad categories, academic solutions, and vendor solutions. Academic solutions are mostly based on three main layers, namely Application, Media Access Control (MAC) and Physical (PHY) which are further divided into two major categories, single-layer solutions, and cross-layer solutions. Single-layer solutions are those which focus on a single layer to enhance the video transmission performance over WLAN. Cross-layer solutions involve two or more layers to provide a single QoS solution for video over WLAN. This thesis has also presented and technically analyzed QoS solutions by three popular vendors. This thesis concludes that single-layer solutions are not directly related to video QoS/QoE, and cross-layer solutions are performing better than single-layer solutions, but they are much more complicated and not easy to be implemented. Most vendors rely on their network infrastructure to provide QoS for multimedia applications. They have their techniques and mechanisms, but the concept of providing QoS/QoE for video is almost the same because they are using the same standards and rely on Wi-Fi Multimedia (WMM) to provide QoS
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