@article{2021_04_azevedo,
author={Azevedo, Roberto Gerson de Albuquerque and Birkbeck, Neil, and
Janatra, Ivan and Adsumilli, Balu and Frossard, Pascal},
title={Multi-feature 360 Video Quality Estimation},
year={2021},
journal={IEEE Open Journal of Circuits and Systems},
note={Accepted for publication},
}

@incollection{2021_00_azevedo,
author={Azevedo, Roberto Gerson de Albuquerque and Khasanova, Renata and
Frossard, Pascal},
title={Omnidirectional Imaging and Deep Learning},
year={2021},
booktitle={Omnidirectional vision},
note={To appear},
}

%%% 2020 %%%

@Misc{2020_10_azevedo,
title="Towards efficient compression of interactive omnidirectional visual
content",
author="Roberto G. de A. Azevedo",
howpublished="\url{https://mmc.committees.comsoc.org/communications-review/}",
year={2020},
month={Oct},
note="IEEE COMSOC MMTC Communications - Review",
publisher="IEEE COMSOC",
}

@article{2020_08_azevedo,
author={Azevedo, Roberto Gerson de Albuquerque and Birkbeck, Neil, and De
Simone, Francesca and Janatra, Ivan and Adsumilli, Balu and Frossard,
Pascal},
journal={IEEE Transactions on Circuits and Systems for Video Technology},
title={Visual Distortions in 360° Videos},
year={2020},
volume={30},
number={8},
pages={2524-2537},
abstract={Omnidirectional (or 360°) images and videos are emergent signals
being used in many areas, such as robotics and virtual/augmented reality. In
particular, for virtual reality applications, they allow an immersive
experience in which the user can interactively navigate through a scene with
three degrees of freedom, wearing a head-mounted display. Current approaches
for capturing, processing, delivering, and displaying 360° content, however,
present many open technical challenges and introduce several types of
distortions in the visual signal. Some of the distortions are specific to the
nature of 360° images and often differ from those encountered in classical
visual communication frameworks. This paper provides a first comprehensive
review of the most common visual distortions that alter 360° signals going
through the different processing elements of the visual communication
pipeline. While their impact on viewers’ visual perception and the
immersive experience at large is still unknown—thus, it is an open research
topic—this review serves the purpose of proposing a taxonomy of the visual
distortions that can be encountered in 360° signals. Their underlying causes
in the end-to-end 360° content distribution pipeline are identified. This
taxonomy is essential as a basis for comparing different processing
techniques, such as visual enhancement, encoding, and streaming strategies,
and allowing the effective design of new algorithms and applications. It is
also a useful resource for the design of psycho-visual studies aiming to
characterize human perception of 360° content in interactive and immersive
applications.},
keywords={Visualization;Videos;Distortion;Cameras;Pipelines;Encoding;Signal
processing algorithms;Omnidirectional video;360-degree video;visual
distortions;artifacts;compression},
doi={10.1109/TCSVT.2019.2927344},
issn={1558-2205},
month={Aug},
}

Omnidirectional (or 360°) images and videos are emergent signals being used in many areas, such as robotics and virtual/augmented reality. In particular, for virtual reality applications, they allow an immersive experience in which the user can interactively navigate through a scene with three degrees of freedom, wearing a head-mounted display. Current approaches for capturing, processing, delivering, and displaying 360° content, however, present many open technical challenges and introduce several types of distortions in the visual signal. Some of the distortions are specific to the nature of 360° images and often differ from those encountered in classical visual communication frameworks. This paper provides a first comprehensive review of the most common visual distortions that alter 360° signals going through the different processing elements of the visual communication pipeline. While their impact on viewers’ visual perception and the immersive experience at large is still unknown—thus, it is an open research topic—this review serves the purpose of proposing a taxonomy of the visual distortions that can be encountered in 360° signals. Their underlying causes in the end-to-end 360° content distribution pipeline are identified. This taxonomy is essential as a basis for comparing different processing techniques, such as visual enhancement, encoding, and streaming strategies, and allowing the effective design of new algorithms and applications. It is also a useful resource for the design of psycho-visual studies aiming to characterize human perception of 360° content in interactive and immersive applications.

@inproceedings{2020_07_mendes,
author={Mendes, Paulo and Guedes, Álan and Moraes, Daniel and De Albuquerque
Azevedo, Roberto Gerson and Colcher, Sérgio},
title={An Authoring Model for Interactive 360 videos},
date={2020-03-28},
year={2020},
month={03},
version=1,
langid={english},
langidopts={variant=american},
eprinttype={arxiv},
eprint={},
abstract={The recent availability of consumer-level head-mounted displays and
omnidirectional cameras has been driving an explosion of 360 video content.
Transforming the original recorded 360 video content in meaningful
interactive applications that support viewers in tasks such as learning,
entertainment, and training tasks, however, is not trivial and requires new
tools. Based on real-world scenarios for 360 interactive videos, in this
paper, we gather a set of requirements and propose an authoring model to
support authors in the process of reasoning and creating 360-degree
interactive video presentations. As a case study, we implement different
interactive 360 applications showing the expressiveness and completeness of
the model in the scope of the target scenarios.},
booktitle={Proceedings of ICME 2020 Workshop: Tools for Creating XR Media
Experiences},
address={London, UK},
note={Accepted for publication},
}

The recent availability of consumer-level head-mounted displays and omnidirectional cameras has been driving an explosion of 360 video content. Transforming the original recorded 360 video content in meaningful interactive applications that support viewers in tasks such as learning, entertainment, and training tasks, however, is not trivial and requires new tools. Based on real-world scenarios for 360 interactive videos, in this paper, we gather a set of requirements and propose an authoring model to support authors in the process of reasoning and creating 360-degree interactive video presentations. As a case study, we implement different interactive 360 applications showing the expressiveness and completeness of the model in the scope of the target scenarios.

@inproceedings{2020_07_azevedo,
author={de Albuquerque Azevedo, Roberto Gerson and Birkbeck, Neil and
Janatra, Ivan and Adsumilli, Balu and Frossard, Pascal},
booktitle={2020 IEEE International Conference on Multimedia and Expo (ICME)},
title={A Viewport-Driven Multi-Metric Fusion Approach for 360-Degree Video
Quality Assessment},
year={2020},
volume={},
number={},
pages={1-6},
abstract={We propose a new viewport-based multi-metric fusion (MMF) approach
for visual quality assessment of 360-degree (omnidirectional) videos. Our
method is based on computing multiple spatio-temporal objective quality
metrics (features) on viewports extracted from 360-degree videos, and
learning a model that combines these features into a metric, which closely
matches subjective quality scores. The main motivations for the proposed
method are that: 1) quality metrics computed on viewports better captures the
user experience than metrics computed on the projection domain; 2) no
individual objective image quality metric always performs best for all types
of visual distortions, while a learned combination of them is able to adapt
to different conditions and produce better results overall. Experimental
results, based on the largest available 360-degree videos quality dataset,
demonstrate that the proposed metric outperforms state-of-the-art 360-degree
and 2D video quality metrics.},
keywords={Measurement;Quality assessment;Visualization;Video
recording;Feature extraction;Two dimensional displays;Distortion;visual
quality assessment;omnidirectional video;360-degree video;multi-metric
fusion},
doi={10.1109/ICME46284.2020.9102936},
issn={1945-788X},
month={July},
}

We propose a new viewport-based multi-metric fusion (MMF) approach for visual quality assessment of 360-degree (omnidirectional) videos. Our method is based on computing multiple spatio-temporal objective quality metrics (features) on viewports extracted from 360-degree videos, and learning a model that combines these features into a metric, which closely matches subjective quality scores. The main motivations for the proposed method are that: 1) quality metrics computed on viewports better captures the user experience than metrics computed on the projection domain; 2) no individual objective image quality metric always performs best for all types of visual distortions, while a learned combination of them is able to adapt to different conditions and produce better results overall. Experimental results, based on the largest available 360-degree videos quality dataset, demonstrate that the proposed metric outperforms state-of-the-art 360-degree and 2D video quality metrics.

@inproceedings{2020_01_azevedo,
title={Subjective and Viewport-based Objective Quality Assessment of
360-degree Videos},
author={Azevedo, Roberto Gerson de Albuquerque and Birkbeck, Neil and
Janatra, Ivan and Adsumilli, Balu and Frossard, Pascal},
pages={6},
year={2020},
month={January},
abstract={Visual distortions in processed 360-degree visual content and
consumed through head-mounted displays (HMDs) are perceived very differently
when compared to traditional 2D content. To better understand how
compression-related artifacts affect the overall perceived quality of
360-degree videos, this paper presents a subjective quality assessment study
and analyzes the performance of objective metrics to correlate with the
gathered subjective scores. In contrast to previous related work, the
proposed study focuses on the equiangular cubemap projection and includes
specific visual distortions (blur, blockiness, H.264 compression, and cubemap
seams) on both monoscopic and stereoscopic sequences. The objective metrics
performance analysis is based on metrics computed in both the projection
domain and the viewports, which is closer to what the user sees. The results
show that overall objective metrics computed on viewports are more correlated
with the subjective scores in our dataset than the same metrics computed in
the projection domain. Moreover, the proposed dataset and objective metrics
analysis serve as a benchmark for the development of new perception-optimized
quality as- sessment algorithms for 360-degree videos, which is still a
largely open research problem.},
url={http://infoscience.epfl.ch/record/271755},
booktitle={Proceedings of Image Quality and System Performance XVII,
Electronic Imaging 2020},
address={Burlingame, California, USA},
}

%%% 2019 %%%

Visual distortions in processed 360-degree visual content and consumed through head-mounted displays (HMDs) are perceived very differently when compared to traditional 2D content. To better understand how compression-related artifacts affect the overall perceived quality of 360-degree videos, this paper presents a subjective quality assessment study and analyzes the performance of objective metrics to correlate with the gathered subjective scores. In contrast to previous related work, the proposed study focuses on the equiangular cubemap projection and includes specific visual distortions (blur, blockiness, H.264 compression, and cubemap seams) on both monoscopic and stereoscopic sequences. The objective metrics performance analysis is based on metrics computed in both the projection domain and the viewports, which is closer to what the user sees. The results show that overall objective metrics computed on viewports are more correlated with the subjective scores in our dataset than the same metrics computed in the projection domain. Moreover, the proposed dataset and objective metrics analysis serve as a benchmark for the development of new perception-optimized quality as- sessment algorithms for 360-degree videos, which is still a largely open research problem.

@inproceedings{2019_12_moreno,
author={M. F. {Moreno} and G. {Lima} and R. {Santos} and R. {Azevedo} and M.
{Endler}},
booktitle={2019 IEEE International Symposium on Multimedia (ISM)},
title={Bridging the Gap between Semantics and Multimedia Processing},
year={2019},
volume={},
number={},
pages={315-3153},
abstract={In this paper, we give an overview of the semantic gap problem in
multimedia and discuss how machine learning and symbolic AI can be combined
to narrow this gap. We describe the gap in terms of a classical architecture
for multimedia processing and discuss a structured approach to bridge it.
This approach combines machine learning (for mapping signals to objects) and
symbolic AI (for linking objects to meanings). Our main goal is to raise
awareness and discuss the challenges involved in this structured approach to
multimedia understanding, especially in the view of the latest developments
in machine learning and symbolic AI.},
}

In this paper, we give an overview of the semantic gap problem in multimedia and discuss how machine learning and symbolic AI can be combined to narrow this gap. We describe the gap in terms of a classical architecture for multimedia processing and discuss a structured approach to bridge it. This approach combines machine learning (for mapping signals to objects) and symbolic AI (for linking objects to meanings). Our main goal is to raise awareness and discuss the challenges involved in this structured approach to multimedia understanding, especially in the view of the latest developments in machine learning and symbolic AI.

@inproceedings{2019_11_silva,
author={Alfredo Silva and Welton de Souza and Daniel Moraes and Roberto
Azevedo and Carlos Soares Neto},
title={Improving the Authoring of Web-based Interactive E-books with
FableJS},
booktitle={Anais da VII Escola Regional de Computação do Ceará, Maranhão
e Piauí},
location={São Luís},
year={2019},
keywords={},
issn={0000-0000},
pages={182--189},
publisher={SBC},
address={Porto Alegre, RS, Brasil},
url={https://sol.sbc.org.br/index.php/ercemapi/article/view/8861},
}

@inproceedings{2019_10_lima,
author={Lima, Thacyla and Azevedo, Roberto Gerson de Albuquerque and Soares
Neto, Carlos de Salles},
title="Improving the reuse support in learning objects authoring tools: a
case study with Cacuriá",
booktitle="WebMedia 2019",
address="Rio de Janeiro-RJ",
days="29-1",
month="oct",
year="2019",
abstract="Reuse as a way of improving educational resources and facilitating
and accelerating the authoring process has been an important theme since the
earliest research efforts on Learning Objects (LOs). This work presents the
evolution of the Cacuriá authoring tool based on a previous work on the
identification of reuse requirements and it analyzes the impact of the
implementation of these good practices through a study with the target tool
audience. Cacuriá enables the creation of interactive educational multimedia
content for the Web and digital TV. The new version of the tool focuses
mainly on the inclusion of three new features that favor reuse: Layouts,
Widgets, and Application Templates. Through these new resources, the author
can build his OA reusing resources created by other authors and has the
possibility to reuse good practices, for example, through previously
validated pedagogical practices. The added functionalities were evaluated in
an experiment with 11 teachers/tutors. The results of this qualitative sample
indicate that the participants of the experiment believe that the new
functionalities improved the creation of reusable OAs both in the creative
aspect and in the reduction of the total development time.",
keywords="Authoring and annotation of content; Document Engineering and Web
Engineering; Interfaces, new interactions, usability, accessibility and user
experience; Testing and validation of systems and applications",
}

Reuse as a way of improving educational resources and facilitating and accelerating the authoring process has been an important theme since the earliest research efforts on Learning Objects (LOs). This work presents the evolution of the Cacuriá authoring tool based on a previous work on the identification of reuse requirements and it analyzes the impact of the implementation of these good practices through a study with the target tool audience. Cacuriá enables the creation of interactive educational multimedia content for the Web and digital TV. The new version of the tool focuses mainly on the inclusion of three new features that favor reuse: Layouts, Widgets, and Application Templates. Through these new resources, the author can build his OA reusing resources created by other authors and has the possibility to reuse good practices, for example, through previously validated pedagogical practices. The added functionalities were evaluated in an experiment with 11 teachers/tutors. The results of this qualitative sample indicate that the participants of the experiment believe that the new functionalities improved the creation of reusable OAs both in the creative aspect and in the reduction of the total development time.

@inproceedings{2019_09b_guedes,
title={Subjective Evaluation of 360-degree Sensory Experiences},
author={Guedes, Álan Lívio Vasconcelos and Azevedo, Roberto Gerson de
Albuquerque and Frossard, Pascal and Barbosa, Simone D.J. and Colcher,
Sérgio},
year={2019},
month={9},
pages={6},
booktitle={IEEE 21st International Workshop on Multimedia Signal Processing},
series={MMSP'19},
address={Kuala Lumpur, Malaysia},
abstract={Traditionally, most multimedia content has been developed to
stimulate two of the human senses, i.e., sight and hearing. Due to recent
technological advancements, however, innovative services have been developed
that provide more realistic, immersive, and engaging experiences to the
audience. Omnidirectional (i.e., 360-degree) video, for instance, is becoming
increasingly popular. It allows the viewer to navigate the full 360-degree
view of a scene from a specific point. In particular, when consumed through
head-mounted displays, 360-degree videos provide increased immersion and
sense of presence. The use of multi-sensory effects ---e.g., wind, vibration,
and scent--- has also been explored by recent work, which allows an improved
experience by stimulating other users' senses through sensory effects that go
beyond the audiovisual content. Understanding how these additional
multi-sensory effects affect the users' perceived quality of experience~(QoE)
in 360-degree, however, is still an open research problem at large. As a step
to better understand the QoE of immersive sensory experiences, this paper
presents a test-bed and discusses a user-focused study on a scenario in which
the user is immersed in the 360-degree video content and is stimulated
through additional sensory effects. Quantitative results indicated that the
sensorial effects can considerably increase the sense of presence of
360-degree videos. Qualitative results provided us with a better view of the
limitations of current technologies and interesting insights such as the
users' sense of surprise.},
}

Traditionally, most multimedia content has been developed to stimulate two of the human senses, i.e., sight and hearing. Due to recent technological advancements, however, innovative services have been developed that provide more realistic, immersive, and engaging experiences to the audience. Omnidirectional (i.e., 360-degree) video, for instance, is becoming increasingly popular. It allows the viewer to navigate the full 360-degree view of a scene from a specific point. In particular, when consumed through head-mounted displays, 360-degree videos provide increased immersion and sense of presence. The use of multi-sensory effects —e.g., wind, vibration, and scent— has also been explored by recent work, which allows an improved experience by stimulating other users' senses through sensory effects that go beyond the audiovisual content. Understanding how these additional multi-sensory effects affect the users' perceived quality of experience (QoE) in 360-degree, however, is still an open research problem at large. As a step to better understand the QoE of immersive sensory experiences, this paper presents a test-bed and discusses a user-focused study on a scenario in which the user is immersed in the 360-degree video content and is stimulated through additional sensory effects. Quantitative results indicated that the sensorial effects can considerably increase the sense of presence of 360-degree videos. Qualitative results provided us with a better view of the limitations of current technologies and interesting insights such as the users' sense of surprise.

@inproceedings{2019_09_guedes,
title={Modeling Multimodal-Multiuser Interactions in Declarative Multimedia
Languages},
author={Guedes, Álan Lívio Vasconcelos and Azevedo, Roberto Gerson de
Albuquerque and Colcher, Sérgio and Barbosa, Simone D.J.},
year={2019},
month={9},
pages={9},
note={Accepted for publication},
booktitle={Proceedings of the 19th ACM Symposium on Document Engineering},
series={DocEng'19},
address={Berlin, Germany},
abstract={Recent advances in hardware and software technologies have given
rise to a new class of human-computer interfaces that both explores multiple
modalities and allows for multiple collaborating users. When compared to the
development of traditional single-user WIMP~(windows, icons, menus,
pointer)-based applications, however, applications supporting the seamless
integration of multimodal-multiuser interactions bring new specification and
runtime requirements. In this paper, with the aim of assisting the
specification of multimedia applications that integrate multimodal-multiuser
interactions, we: (1)~propose the MMAM~(Multimodal-Multiuser Authoring
Model); (2)~present three different instantiations of it (in NCL, HTML, and a
block-based syntax); and (3)~evaluate the proposed model through a user
study. MMAM enables programmers to design and ponder different solutions for
applications with multimodal-multiuser requirements. Its instantiations allow
integrating the solution in real execution environments, such as the Web and
Digital TV, and served as proofs of concept about the feasibility of our
model and enabled us to perform the user study. The user study focused on
capturing evidence of both the user understanding and the user acceptance of
the proposed model. We asked developers to perform tasks using MMAM and then
answer a TAM~(Technology Acceptance Model)-based questionnaire focused on
both the model and its instantiations. As results, the study indicates that
the participants easily understood the model~(most of them performed the
required tasks with minor or no errors) and found it both useful and easy to
use. 94.47\% of the participants gave positive answers to the block-based
representation TAM questions, whereas 75.17\% of them gave positive answers
to the instantiations-related questions.},
}

Recent advances in hardware and software technologies have given rise to a new class of human-computer interfaces that both explores multiple modalities and allows for multiple collaborating users. When compared to the development of traditional single-user WIMP (windows, icons, menus, pointer)-based applications, however, applications supporting the seamless integration of multimodal-multiuser interactions bring new specification and runtime requirements. In this paper, with the aim of assisting the specification of multimedia applications that integrate multimodal-multiuser interactions, we: (1) propose the MMAM (Multimodal-Multiuser Authoring Model); (2) present three different instantiations of it (in NCL, HTML, and a block-based syntax); and (3) evaluate the proposed model through a user study. MMAM enables programmers to design and ponder different solutions for applications with multimodal-multiuser requirements. Its instantiations allow integrating the solution in real execution environments, such as the Web and Digital TV, and served as proofs of concept about the feasibility of our model and enabled us to perform the user study. The user study focused on capturing evidence of both the user understanding and the user acceptance of the proposed model. We asked developers to perform tasks using MMAM and then answer a TAM (Technology Acceptance Model)-based questionnaire focused on both the model and its instantiations. As results, the study indicates that the participants easily understood the model (most of them performed the required tasks with minor or no errors) and found it both useful and easy to use. 94.47% of the participants gave positive answers to the block-based representation TAM questions, whereas 75.17% of them gave positive answers to the instantiations-related questions.

@inproceedings{2019_09_desimone,
title={Graph-based detection of seams in 360-degree images},
author={de Simone*, Francesca and Azevedo*, Roberto Gerson de Albuquerque and
Sohyeong, Kim and Frossard, Pascal},
month={Sept},
year={2019},
doi={10.1109/ICIP.2019.8803578},
issn={2381-8549},
pages={3776-3780},
note={*Equal contributions.},
booktitle={2019 IEEE International Conference on Image Processing (ICIP)},
series={ICIP'19},
address={Taipei, Taiwan},
keywords={Omnidirectional image; cube map projection; compression; visual
distortion; quality metric},
abstract={In this paper, we propose an algorithm to detect a specific kind of
distortions, referred to as seams, which commonly occur when a 360-degree
image is represented in planar domain, e.g, via the Cube Map (CM) projection,
and undergoes lossy compression. The proposed algorithm exploits a
graph-based representation to account for the actual sampling density of the
360-degree signal in the native spherical domain. The CM image is considered
as a signal lying on a graph defined on the spherical surface. The spectra of
the processed and the original signals, computed by applying the Graph
Fourier Transform, are compared to detect the seams. To test our method a
dataset of compressed CM 360-degree images, annotated by experts, has been
created. The performance of the proposed algorithm is compared to those
achieved by baseline metrics, as well as to the same approach based on
spectral comparison but ignoring the spherical nature of the signal. The
experimental results show that the proposed method has the best performance
and can successfully detect up to approximately 90\% of visible seams on our
dataset.},
}

In this paper, we propose an algorithm to detect a specific kind of distortions, referred to as seams, which commonly occur when a 360-degree image is represented in planar domain, e.g, via the Cube Map (CM) projection, and undergoes lossy compression. The proposed algorithm exploits a graph-based representation to account for the actual sampling density of the 360-degree signal in the native spherical domain. The CM image is considered as a signal lying on a graph defined on the spherical surface. The spectra of the processed and the original signals, computed by applying the Graph Fourier Transform, are compared to detect the seams. To test our method a dataset of compressed CM 360-degree images, annotated by experts, has been created. The performance of the proposed algorithm is compared to those achieved by baseline metrics, as well as to the same approach based on spectral comparison but ignoring the spherical nature of the signal. The experimental results show that the proposed method has the best performance and can successfully detect up to approximately 90% of visible seams on our dataset.

@inproceedings{2019_06_azevedo,
author={Azevedo, Roberto Gerson de Albuquerque and Birkbeck, Neil and
Janatra, Ivan and Adsumilli, Balu and Frossard, Pascal},
title={On the First JND and Break in Presence of 360-degree Content: An
Exploratory Study},
booktitle={Proceedings of the 11th ACM Workshop on Immersive Mixed and
Virtual Environment Systems},
series={MMVE '19},
year={2019},
isbn={978-1-4503-6299-3},
location={Amherst, Massachusetts},
pages={1--3},
numpages={3},
url={http://doi.acm.org/10.1145/3304113.3326115},
doi={10.1145/3304113.3326115},
acmid={3326115},
publisher={ACM},
address={New York, NY, USA},
keywords={360-degree video, JND, presence, visual distortions, visual
quality},
abstract={Unlike traditional planar 2D visual content, immersive 360-degree
images and videos undergo particular processing steps and are intended to be
consumed via head-mounted displays (HMDs). To get a deeper understanding on
the perception of 360-degree visual distortions when consumed through HMDs,
we perform an exploratory task-based subjective study in which we have asked
subjects to define the first noticeable difference and break-in-presence
points when incrementally adding specific compression artifacts. The results
of our study: give insights on the range of allowed visual distortions for
360-degree content; show that the added visual distortions are more tolerable
in mono than in stereoscopic 3D; and identify issues with current 360-degree
objective quality metrics.},
}

%%% 2018 %%%
%

Unlike traditional planar 2D visual content, immersive 360-degree images and videos undergo particular processing steps and are intended to be consumed via head-mounted displays (HMDs). To get a deeper understanding on the perception of 360-degree visual distortions when consumed through HMDs, we perform an exploratory task-based subjective study in which we have asked subjects to define the first noticeable difference and break-in-presence points when incrementally adding specific compression artifacts. The results of our study: give insights on the range of allowed visual distortions for 360-degree content; show that the added visual distortions are more tolerable in mono than in stereoscopic 3D; and identify issues with current 360-degree objective quality metrics.

@inproceedings{2018_08_mendes,
author={Mendes, Paulo Renato Conceição and Azevedo, Roberto Gerson de
Albuquerque and de Oliveira, Ruy Guilherme Silva and Soares Neto, Carlos de
Salles},
title={Exploring an AR-based User Interface for Authoring Multimedia
Presentations},
booktitle={DocEng 2018},
address={Halifax, CA},
month={aug},
year={2018},
abstract={This paper describes the BumbAR approach for composing multimedia
presentations and evaluates it through a qualitative study based on the
Technology Acceptance Model (TAM). The BumbAR proposal is based on the
event-condition-action model of Nested Context Model (NCM) and explores the
use of augmented reality and real-world objects (markers) as an innovative
user interface to specify the behavior and relationships between the media
objects in a presentation. The qualitative study aimed at measuring the
users' attitude towards using BumbAR and an augmented reality environment for
authoring multimedia presentations. The results show that the participants
found the BumbAR approach both useful and easy-to-use, while most of them
(66,67\%) found the system more convenient than traditional desktop-based
authoring tools.},
}

%
%
%%% 2017 %%%

This paper describes the BumbAR approach for composing multimedia presentations and evaluates it through a qualitative study based on the Technology Acceptance Model (TAM). The BumbAR proposal is based on the event-condition-action model of Nested Context Model (NCM) and explores the use of augmented reality and real-world objects (markers) as an innovative user interface to specify the behavior and relationships between the media objects in a presentation. The qualitative study aimed at measuring the users' attitude towards using BumbAR and an augmented reality environment for authoring multimedia presentations. The results show that the participants found the BumbAR approach both useful and easy-to-use, while most of them (66,67%) found the system more convenient than traditional desktop-based authoring tools.

@incollection{2017_10_colcher,
author={Colcher, Sérgio and Guedes, Álan Lívio Vasconcelos and Azevedo,
Roberto Gerson de Albuquerque and Lima, Guilherme F. and Santos, Rodrigo
Costa Mesquita and Busson, Antônio José Grandson},
title={Projetos Atuais e Visão de Futuro do Laboratório TeleMídia/PUC-Rio
em Videocolaboração},
editor={Ciuffo, Leandro and Roesler, Valter},
booktitle={O Futuro da Videocolaboração: perspectivas},
series={Anais do IV CT-Vídeo. WebMedia '17},
year={2017},
isbn={978-85-7669-381-9},
location={Gramado, RS, Brazil},
pages={207--232},
publisher={Sociedade Brasileira de Computação},
address={New York, NY, USA},
language={Portuguese},
abstract={Since the early 1990's, the TeleMídia laboratory of the Department
of Informatics of PUC-Rio researches and trains people in the areas of
multimedia and hypermedia, which include interactive videos and video
collaboration as important subareas. This chapter presents the main research
lines and projects of the laboratory and discusses the future vision of the
authors about interactive videos and video collaboration.},
url_paper={http://www.telemidia.puc-rio.br/files/biblio/2017_10_colcher.pdf},
}

Since the early 1990's, the TeleMídia laboratory of the Department of Informatics of PUC-Rio researches and trains people in the areas of multimedia and hypermedia, which include interactive videos and video collaboration as important subareas. This chapter presents the main research lines and projects of the laboratory and discusses the future vision of the authors about interactive videos and video collaboration.

@inproceedings{lima_2017,
author="Lima, Guilherme and Azevedo, Roberto Gerson de Albuquerque and
Colcher, Sérgio and Haeusler, Edward Hermann",
title="Converting NCL documents to Smix and fixing their semantics and
interpretation in the process",
booktitle="WebMedia 2017",
address="Gramado, RS",
days="17-20",
month="oct",
year="2017",
abstract="In this paper, we describe the conversion of NCL to Smix and
discuss its main implications. NCL is a declarative language for the
specification of interactive multimedia presentations which was adopted by
the ITU-T H.761 recommendation for interoperable IPTV services. Smix is an
NCL-like, domain-specific language with a similar purpose, but with a much
simpler and more precise semantics. By implementing NCL over Smix, we bring
to the former the notions of reaction and execution instants, and with them
some benefits. From a practical perspective, we fix the semantics of the
converted documents, get a leaner NCL player (the Smix interpreter), and
simplify further conversions and interpretations. From a systems-design
perspective, the structured conversion of NCL to Smix helps us tame the
complexity of mapping the user-oriented constructs of NCL into the
machine-oriented primitives and operations that realize them as a multimedia
application. In the paper, we present both NCL and Smix, discuss related work
on document conversion, and detail the proposed conversion process together
with its prototype implementation.",
keywords="Architectures, processes and methodologies; Content analysis,
coding and processing; Content synchronization and presentation",
url_paper={http://www.telemidia.puc-rio.br/files/biblio/2017_10_lima.pdf},
}

In this paper, we describe the conversion of NCL to Smix and discuss its main implications. NCL is a declarative language for the specification of interactive multimedia presentations which was adopted by the ITU-T H.761 recommendation for interoperable IPTV services. Smix is an NCL-like, domain-specific language with a similar purpose, but with a much simpler and more precise semantics. By implementing NCL over Smix, we bring to the former the notions of reaction and execution instants, and with them some benefits. From a practical perspective, we fix the semantics of the converted documents, get a leaner NCL player (the Smix interpreter), and simplify further conversions and interpretations. From a systems-design perspective, the structured conversion of NCL to Smix helps us tame the complexity of mapping the user-oriented constructs of NCL into the machine-oriented primitives and operations that realize them as a multimedia application. In the paper, we present both NCL and Smix, discuss related work on document conversion, and detail the proposed conversion process together with its prototype implementation.

@inproceedings{pinto_2017,
author={Pinto, Hedvan Fernandes and Soares Neto, Carlos De Salles and
Colcher, S{\'e}rgio and Azevedo, Roberto Gerson de Albuquerque},
title={The F\'{a}bulas Model for Authoring Web-based Children's eBooks},
booktitle={Proceedings of the 2017 ACM Symposium on Document Engineering},
series={DocEng '17},
year={2017},
isbn={978-1-4503-4689-4},
location={Valletta, Malta},
pages={19--28},
numpages={10},
url={http://doi.acm.org/10.1145/3103010.3103016},
doi={10.1145/3103010.3103016},
acmid={3103016},
publisher={ACM},
address={New York, NY, USA},
keywords={conceptual model, interactive ebook, multimedia authoring},
abstract={Nowadays, tablets and smartphones are commonly used by children for
both entertainment and education purposes. In special, interactive multimedia
eBooks running on those devices allow a richer experience when compared to
traditional text-only books, being potentially more engaging and entertaining
to readers. However, to explore the most exciting features in these
environments, authors are currently left alone in the sense that there is no
high level (less technical) support, and these features are usually
accessible only through programming or some other technical skill. In this
work, we aim at extracting the main features on enhanced children's eBooks
and propose a model, named Fábulas - the Portuguese word for fables -that
allows authors to create interactive multimedia children's eBooks
declaratively. The model was conceived by taking, as a starting point, a
systematic analysis of the common concepts, with the focus on identifying and
categorizing recurring characteristics and pointing out functional and
non-functional requirements that establish a strong orientation towards the
set of desirable abstractions of an underlying model. Moreover, the paper
presents a case study for the implementation of Fábulas on the Web, and
discusses the authoring of a complete interactive story over it.},
}

Nowadays, tablets and smartphones are commonly used by children for both entertainment and education purposes. In special, interactive multimedia eBooks running on those devices allow a richer experience when compared to traditional text-only books, being potentially more engaging and entertaining to readers. However, to explore the most exciting features in these environments, authors are currently left alone in the sense that there is no high level (less technical) support, and these features are usually accessible only through programming or some other technical skill. In this work, we aim at extracting the main features on enhanced children's eBooks and propose a model, named Fábulas - the Portuguese word for fables -that allows authors to create interactive multimedia children's eBooks declaratively. The model was conceived by taking, as a starting point, a systematic analysis of the common concepts, with the focus on identifying and categorizing recurring characteristics and pointing out functional and non-functional requirements that establish a strong orientation towards the set of desirable abstractions of an underlying model. Moreover, the paper presents a case study for the implementation of Fábulas on the Web, and discusses the authoring of a complete interactive story over it.

@inproceedings{2017_07_busson,
author={Busson, Antonio Jos{\'e} G. and Damasceno, Andr{\'e} Luiz de B. and
Azevedo, Roberto Gerson de Albuquerque and Neto, Carlos de Salles Soares and
Lima, Thacyla de Sousa and Colcher, S{\'e}rgio},
title={A Hypervideo Model for Learning Objects},
booktitle={Proceedings of the 28th ACM Conference on Hypertext and Social
Media},
series={HT '17},
year={2017},
isbn={978-1-4503-4708-2},
location={Prague, Czech Republic},
pages={245--253},
numpages={9},
url={http://doi.acm.org/10.1145/3078714.3078739},
doi={10.1145/3078714.3078739},
acmid={3078739},
publisher={ACM},
address={New York, NY, USA},
keywords={hypervideos, learning objects, scenesync},
abstract={Learning Objects (LOs) are entities that can be used, reused, or
referred during the teaching process. They are commonly embedded into
documents that establish spatial and temporal relationships on their
contents. Hypervideos LOs allow students to individualize their learning
experience with non-linear browsing mechanisms and content adaptation. This
paper presents a survey of features for a set of documents representing such
LOs as well as desirable aspects that should be expressed during the
authoring phase. Also, this paper presents a conceptual model that fits such
requirements. The model is implemented by SceneSync, a domain specific
language focused on the synchronization and temporal behavior of LOs. As a
result of the work, we present a set of LOs specified in SceneSync and a
discussion about the identified features, which confirm the expressiveness
and applicability of the model.},
}

Learning Objects (LOs) are entities that can be used, reused, or referred during the teaching process. They are commonly embedded into documents that establish spatial and temporal relationships on their contents. Hypervideos LOs allow students to individualize their learning experience with non-linear browsing mechanisms and content adaptation. This paper presents a survey of features for a set of documents representing such LOs as well as desirable aspects that should be expressed during the authoring phase. Also, this paper presents a conceptual model that fits such requirements. The model is implemented by SceneSync, a domain specific language focused on the synchronization and temporal behavior of LOs. As a result of the work, we present a set of LOs specified in SceneSync and a discussion about the identified features, which confirm the expressiveness and applicability of the model.

@article{2017_02_guedes,
author="Guedes, {\'A}lan L{\'i}vio Vasconcelos and Azevedo, Roberto Gerson de
Albuquerque and Barbosa, Simone Diniz Junqueira",
title="Extending multimedia languages to support multimodal user
interactions",
journal="Multimedia Tools and Applications",
year="2017",
volume="76",
number="4",
pages="5691--5720",
abstract="Historically, the Multimedia community research has focused on
output modalities, through studies on timing and multimedia processing. The
Multimodal Interaction community, on the other hand, has focused on
user-generated modalities, through studies on Multimodal User Interfaces
(MUI). In this paper, aiming to assist the development of multimedia
applications with MUIs, we propose the integration of concepts from those two
communities in a unique high-level programming framework. The framework
integrates user modalities ---both user-generated (e.g., speech, gestures)
and user-consumed (e.g., audiovisual, haptic)--- in declarative programming
languages for the specification of interactive multimedia applications. To
illustrate our approach, we instantiate the framework in the NCL (Nested
Context Language) multimedia language. NCL is the declarative language for
developing interactive applications for Brazilian Digital TV and an ITU-T
Recommendation for IPTV services. To help evaluate our approach, we discuss a
usage scenario and implement it as an NCL application extended with the
proposed multimodal features. Also, we compare the expressiveness of the
multimodal NCL against existing multimedia and multimodal languages, for both
input and output modalities.",
issn="1573-7721",
doi="10.1007/s11042-016-3846-8",
url="http://dx.doi.org/10.1007/s11042-016-3846-8",
}

%%% 2016 %%%

Historically, the Multimedia community research has focused on output modalities, through studies on timing and multimedia processing. The Multimodal Interaction community, on the other hand, has focused on user-generated modalities, through studies on Multimodal User Interfaces (MUI). In this paper, aiming to assist the development of multimedia applications with MUIs, we propose the integration of concepts from those two communities in a unique high-level programming framework. The framework integrates user modalities —both user-generated (e.g., speech, gestures) and user-consumed (e.g., audiovisual, haptic)— in declarative programming languages for the specification of interactive multimedia applications. To illustrate our approach, we instantiate the framework in the NCL (Nested Context Language) multimedia language. NCL is the declarative language for developing interactive applications for Brazilian Digital TV and an ITU-T Recommendation for IPTV services. To help evaluate our approach, we discuss a usage scenario and implement it as an NCL application extended with the proposed multimodal features. Also, we compare the expressiveness of the multimodal NCL against existing multimedia and multimodal languages, for both input and output modalities.

@incollection{2016_11_lima,
author={Lima, Guilherme Ferreira and Mesquita, Rodrigo Costa and Azevedo,
Roberto Gerson de Albuquerque},
title={Programando Aplicacões Multim{\'i}dia no GStreamer},
booktitle={Anais do XXII Simp{\'o}sio Brasileiro de Sistemas Multim{\'i}dia e
Web (Vol. 3): Minicursos},
pages={},
publisher={SBC},
year={2016},
month={November},
editor={},
address={Teresina, PI, Brazil},
language={Portuguese},
isbn={978-85-7669-333-8},
abstract={This short course is an introduction to GStreamer, one of the main
free/open-source frameworks for multimedia processing. We start presenting
GStreamer, its architecture and the dataflow programming model, and then
adopt a hands-on approach. Starting with an example, a simple video player,
we introduce the main concepts of GStreamer’s basic C API and implement
them over the initial example incrementally, so that at the end of the course
we get a complete video player with support for the usual playback operations
(start, stop, pause, seek, fast-forward, and rewind). We also discuss sample
filters—processing elements that manipulate audio and video samples—and
present some of the filters natively available in GStreamer. Moreover, we
show how one can extend the framework by creating a plugin with a custom
filter that manipulates video samples. The prerequisite for the short course
is a basic knowledge of the C programming language. At the end of the course,
we expect that participants acquire a general view of GStreamer, and be able
to create simple multimedia applications and explore its more advanced
features.},
}

This short course is an introduction to GStreamer, one of the main free/open-source frameworks for multimedia processing. We start presenting GStreamer, its architecture and the dataflow programming model, and then adopt a hands-on approach. Starting with an example, a simple video player, we introduce the main concepts of GStreamer’s basic C API and implement them over the initial example incrementally, so that at the end of the course we get a complete video player with support for the usual playback operations (start, stop, pause, seek, fast-forward, and rewind). We also discuss sample filters—processing elements that manipulate audio and video samples—and present some of the filters natively available in GStreamer. Moreover, we show how one can extend the framework by creating a plugin with a custom filter that manipulates video samples. The prerequisite for the short course is a basic knowledge of the C programming language. At the end of the course, we expect that participants acquire a general view of GStreamer, and be able to create simple multimedia applications and explore its more advanced features.

@inproceedings{2016_11_gomes,
author={Gomes, Lucas and Mesquita, Rodrigo Costa and Azevedo, Roberto Gerson
de Albuquerque},
title={SXMLua: Definindo estilos de documentos XML em Lua},
booktitle={Proceedings of the 13rd Workshop on Undergratuate Work on the
Brazilian Symposium on Multimedia and the Web},
series={WebMedia '16},
publisher={SBC},
year={2016},
month={November},
editor={},
address={Teresina, PI, Brazil},
language={Portuguese},
abstract={This paper proposes SXMLua (Styling XML through Lua), a
pre-processor and a library supporting the definition of stylesheets for XML
documents using Lua. SXMLua was inspired by the CSS language, and, similar to
it, allows the separation between the presentation and the content
specification of XML documents. It also provides (through the Lua language)
facilities that are not natively supported by CSS, such as variables and
functions. Besides presenting SXMLua, in this paper, we also discuss its use
for specifying stylesheets for interactive digital TV applications using NCL
(Nested Context Language).},
}

This paper proposes SXMLua (Styling XML through Lua), a pre-processor and a library supporting the definition of stylesheets for XML documents using Lua. SXMLua was inspired by the CSS language, and, similar to it, allows the separation between the presentation and the content specification of XML documents. It also provides (through the Lua language) facilities that are not natively supported by CSS, such as variables and functions. Besides presenting SXMLua, in this paper, we also discuss its use for specifying stylesheets for interactive digital TV applications using NCL (Nested Context Language).

@inproceedings{2016_11_guedes,
author={Guedes, \'{A}lan L.V. and Azevedo, Roberto Gerson de Albuquerque and
Colcher, S{\'e}rgio and Barbosa, Simone D.J.},
title={Extending NCL to Support Multiuser and Multimodal Interactions},
booktitle={Proceedings of the 22nd Brazilian Symposium on Multimedia and the
Web},
series={Webmedia '16},
year={2016},
isbn={978-1-4503-4512-5},
location={Teresina, Piauí; State, Brazil},
pages={39--46},
numpages={8},
url={http://doi.acm.org/10.1145/2976796.2976869},
doi={10.1145/2976796.2976869},
acmid={2976869},
publisher={ACM},
address={New York, NY, USA},
keywords={NCL, ginga-NCL, multimedia languages, multimodal interactions,
multiuser interactions, nested context language},
abstract={Recent advances in technologies for speech, touch and gesture
recognition have given rise to a new class of user interfaces that does not
only explore multiple modalities but also allows for multiple interacting
users. Even so, current declarative multimedia languages e.g. HTML, SMIL, and
NCL?support only limited forms of user input (mainly keyboard and mouse) for
a single user. In this paper, we aim at studying how the NCL multimedia
language could take advantage of those new recognition technologies. To do
so, we revisit the model behind NCL, named NCM (Nested Context Model), and
extend it with first-class concepts supporting multiuser and multimodal
features. To evaluate our approach, we instantiate the proposal and discuss
some usage scenarios, developed as NCL applications with our extended
features.},
note={Acceptance ratio: 30\%},
}

Recent advances in technologies for speech, touch and gesture recognition have given rise to a new class of user interfaces that does not only explore multiple modalities but also allows for multiple interacting users. Even so, current declarative multimedia languages e.g. HTML, SMIL, and NCL?support only limited forms of user input (mainly keyboard and mouse) for a single user. In this paper, we aim at studying how the NCL multimedia language could take advantage of those new recognition technologies. To do so, we revisit the model behind NCL, named NCM (Nested Context Model), and extend it with first-class concepts supporting multiuser and multimodal features. To evaluate our approach, we instantiate the proposal and discuss some usage scenarios, developed as NCL applications with our extended features.

@inproceedings{2016_07_azevedo,
author={Azevedo, Roberto Gerson de Albuquerque and Lima, Guilherme Ferreira},
booktitle={2016 3DTV-Conference: The True Vision - Capture, Transmission and
Display of 3D Video (3DTV-CON)},
title={A graphics composition architecture for multimedia applications based
on layered-depth-image},
year={2016},
pages={1-4},
keywords={Kernel;Media;Multimedia communication;Real-time systems;Rendering
(computer graphics);Three-dimensional displays;3D Video;Graphics
Composition;Layered-depth Image;Multimedia Applications},
doi={10.1109/3DTV.2016.7548882},
month={July},
address={Hamburg, Germany},
abstract={We present a graphics architecture for the seamless integration of
3DV objects into ordinary 2D/3D multimedia applications. The architecture is
based on layered-depth-image (LDI) and supports the real-time rendering of
multiple views for multi-view 3D displays. We also present a prototype
implementation of the proposed architecture in OpenCL, and discuss
experimental results. The results indicate that the proposed approach leads
to better results than other state-of-art graphics architecture for
multimedia application.},
}

%%% 2015 %%%

We present a graphics architecture for the seamless integration of 3DV objects into ordinary 2D/3D multimedia applications. The architecture is based on layered-depth-image (LDI) and supports the real-time rendering of multiple views for multi-view 3D displays. We also present a prototype implementation of the proposed architecture in OpenCL, and discuss experimental results. The results indicate that the proposed approach leads to better results than other state-of-art graphics architecture for multimedia application.

@PhDThesis{2015_12_azevedo,
author={Azevedo, Roberto Gerson de Albuquerque},
title={Supporting multimedia applications in stereoscopic and depth-based 3D
video systems},
type={Ph.D. thesis},
month={December},
year={2015},
location={Rio de Janeiro, RJ},
advisor={Soares, Luiz Fernando Gomes},
school={Department of Informatics, PUC-Rio},
url={http://www2.dbd.puc-rio.br/pergamum/tesesabertas/1021805_2015_completo.pdf},
}

@inproceedings{2015_10_guedes,
author={Guedes, Alan Lívio Vasconcelos and Azevedo, Roberto Gerson de
Albuquerque and Moreno, Marcio Ferreira and Soares, Luiz Fernando Gomes},
title={Specification of Multimodal Interactions in {NCL} },
booktitle={Proceedings of the 21st Brazilian Symposium on Multimedia and the
Web},
series={WebMedia '15},
year={2015},
isbn={978-1-4503-3959-9},
location={Manaus, Brazil},
pages={181--187},
numpages={7},
url={http://doi.acm.org/10.1145/2820426.2820436},
doi={10.1145/2820426.2820436},
acmid={2820436},
publisher={ACM},
address={New York, NY, USA},
keywords={mui, multimodal interactions, multimodal interfaces, ncl, nested
context language},
abstract={This paper proposes an approach to integrate multimodal
events--both user-generated, e.g., audio recognizer, motion sensors; and
user-consumed, e.g., speech synthesizer, haptic synthesizer--into programming
languages for the declarative specification of multimedia applications. More
precisely, it presents extensions to the NCL (Nested Context Language)
multimedia language. NCL is the standard declarative language for the
development of interactive applications for Brazilian Digital TV and an ITU-T
Recommendation for IPTV services. NCL applications extended with the
multimodal features are presented as results. Historically, Human-Computer
Interaction research community has been focusing on user-generated
modalities, through studies on the user interaction. On the other hand,
Multimedia community has been focusing on output modalities, through studies
on timing and multimedia processing. The proposals in this paper is an
attempt to integrate concepts of both research communities in a unique
high-level programming framework, which aims to assist the authoring of
multimedia/multimodal applications.},
note={Acceptance ratio: 34\%},
}

This paper proposes an approach to integrate multimodal events–both user-generated, e.g., audio recognizer, motion sensors; and user-consumed, e.g., speech synthesizer, haptic synthesizer–into programming languages for the declarative specification of multimedia applications. More precisely, it presents extensions to the NCL (Nested Context Language) multimedia language. NCL is the standard declarative language for the development of interactive applications for Brazilian Digital TV and an ITU-T Recommendation for IPTV services. NCL applications extended with the multimodal features are presented as results. Historically, Human-Computer Interaction research community has been focusing on user-generated modalities, through studies on the user interaction. On the other hand, Multimedia community has been focusing on output modalities, through studies on timing and multimedia processing. The proposals in this paper is an attempt to integrate concepts of both research communities in a unique high-level programming framework, which aims to assist the authoring of multimedia/multimodal applications.

@inproceedings{2015_09_azevedo,
author={Azevedo, Roberto Gerson de Albuquerque and Lima, Guilherme F. and
Soares, Luiz Fernando Gomes},
title={An Approach to Convert {NCL} Applications into Stereoscopic 3D},
booktitle={Proceedings of the 2015 Symposium on Document Engineering},
series={DocEng '15},
year={2015},
isbn={978-1-4503-3307-8},
location={Lausanne, Switzerland},
pages={177--186},
numpages={10},
url={http://doi.acm.org/10.1145/2682571.2797064},
doi={10.1145/2682571.2797064},
acmid={2797064},
publisher={ACM},
address={New York, NY, USA},
keywords={3dtv, document processing, ginga, ncl, stereoscopic multimedia
applications},
abstract={This paper presents and discusses the internal operation of NCLSC
(NCL Stereo Converter): a tool to convert a 2D interactive multimedia
application annotated with depth information to a stereoscopic-multimedia
application. Stereoscopic-multimedia applications are those that codify both
the left-eye and right-eye views, as required by stereoscopic 3D displays.
NCLSC takes as input an NCL (Nested Context Language) document and outputs an
NCL stereoscopic application codified in side-by-side or top-bottom format
(both common input formats for 3DTV sets). NCL is the declarative language
adopted in most Latin America countries for terrestrial digital TV middleware
systems and the ITU-T H.761 Recommendation for IPTV services. However, the
proposed approach is not restricted to NCL and can be used by other
languages. The depth annotation allows for positioning each 2D graphical
component in a layered (2.5D or 2D+depth) user interface. It is used by NCLSC
to compute the screen parallax (offset) between the graphical elements in the
left and right views of the resulting stereoscopic application. When the
resulting application is presented on stereoscopic 3D displays, such screen
parallax induces retinal disparity, which creates the illusion of floating
flat-2D graphical elements. NCLSC does not require any additional native
middleware support to run in currently available 3D-enabled TV sets.
Moreover, NCLSC can adapt, at run-time, the output application to different
display sizes, viewer distances, and viewer preferences, which are usually
required for a proper balance between artistic effects and user experience.},
note={Acceptance ratio: 35\%},
}

%%% 2014 %%%

This paper presents and discusses the internal operation of NCLSC (NCL Stereo Converter): a tool to convert a 2D interactive multimedia application annotated with depth information to a stereoscopic-multimedia application. Stereoscopic-multimedia applications are those that codify both the left-eye and right-eye views, as required by stereoscopic 3D displays. NCLSC takes as input an NCL (Nested Context Language) document and outputs an NCL stereoscopic application codified in side-by-side or top-bottom format (both common input formats for 3DTV sets). NCL is the declarative language adopted in most Latin America countries for terrestrial digital TV middleware systems and the ITU-T H.761 Recommendation for IPTV services. However, the proposed approach is not restricted to NCL and can be used by other languages. The depth annotation allows for positioning each 2D graphical component in a layered (2.5D or 2D+depth) user interface. It is used by NCLSC to compute the screen parallax (offset) between the graphical elements in the left and right views of the resulting stereoscopic application. When the resulting application is presented on stereoscopic 3D displays, such screen parallax induces retinal disparity, which creates the illusion of floating flat-2D graphical elements. NCLSC does not require any additional native middleware support to run in currently available 3D-enabled TV sets. Moreover, NCLSC can adapt, at run-time, the output application to different display sizes, viewer distances, and viewer preferences, which are usually required for a proper balance between artistic effects and user experience.

@incollection{2014_12_azevedo,
year={2014},
isbn={978-3-319-14248-7},
booktitle={Advances in Visual Computing},
volume={8887},
series={Lecture Notes in Computer Science},
editor={Bebis, George and Boyle, Richard and Parvin, Bahram and Koracin,
Darko and McMahan, Ryan and Jerald, Jason and Zhang, Hui and Drucker,
StevenM. and Kambhamettu, Chandra and El Choubassi, Maha and Deng, Zhigang
and Carlson, Mark},
doi={10.1007/978-3-319-14249-4_10},
title={Real-Time Depth-Image-Based Rendering for {3DTV} Using {OpenCL}},
url={http://dx.doi.org/10.1007/978-3-319-14249-4_10},
publisher={Springer International Publishing},
keywords={DIBR; OpenCL; GPGPU; Stereoscopic; 3DTV},
author={Azevedo, Roberto Gerson de Albuquerque and Ismério, Fernando and
Raposo, Alberto Barbosa and Soares, Luiz Fernando Gomes},
pages={97-106},
note={Acceptance ratio: 26.4\%},
month={July},
}

@inproceedings{2014_07a_azevedo,
author={Azevedo, Roberto Gerson de Albuquerque and Soares, Luiz Fernando
Gomes},
booktitle={3DTV-Conference: The True Vision - Capture, Transmission and
Display of 3D Video (3DTV-CON), 2014},
title={Ginga extensions to support depth-based 3D media},
year={2014},
month={July},
pages={1-4},
keywords={3DTV;Ginga;ISDB-T;Multimedia languages;NCL;Video-plus-depth},
doi={10.1109/3DTV.2014.6874715},
url={http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=\&arnumber=6874715\&isnumber=6874707},
}

@article{2014_07b_azevedo,
year={2014},
issn={1380-7501},
journal={Multimedia Tools and Applications},
doi={10.1007/s11042-012-1216-8},
title={Composer: meeting non-functional aspects of hypermedia authoring
environment},
publisher={Springer US},
keywords={Hypermedia authoring tools; Non-functional requirements;
Microkernel-based architecture},
author={Azevedo, Roberto Gerson de Albuquerque and Araújo, Eduardo Cruz and
Lima, Bruno and Soares, Luiz Fernando Gomes and Moreno, Marcelo Ferreira},
pages={1-30},
month={July},
abstract={This paper discusses the importance of non-functional requirements
in the design of hypermedia authoring tools, which typically provides
multiple graphical abstractions (views). It focuses on creating products and
services that operate robustly across a broad range of environments, and that
take into account the changeable needs of their users over time, as they
become more familiar with the tool. In order to meet these non-functional
aspects, this paper proposes a microkernel-based architecture for authoring
tools, where the microkernel is responsible for instantiating the requested
extensions (plugins), maintaining the core data model that represents the
hypermedia document under development, and notifying changes in this model to
plugins interested in them. Based on the proposed architecture, a new version
of Composer (an NCL authoring tool) is presented, rewritten from scratch.
Results from experiments show that the discussed non-functional requirements
are adequately met.},
}

%%% 2013 %%%

This paper discusses the importance of non-functional requirements in the design of hypermedia authoring tools, which typically provides multiple graphical abstractions (views). It focuses on creating products and services that operate robustly across a broad range of environments, and that take into account the changeable needs of their users over time, as they become more familiar with the tool. In order to meet these non-functional aspects, this paper proposes a microkernel-based architecture for authoring tools, where the microkernel is responsible for instantiating the requested extensions (plugins), maintaining the core data model that represents the hypermedia document under development, and notifying changes in this model to plugins interested in them. Based on the proposed architecture, a new version of Composer (an NCL authoring tool) is presented, rewritten from scratch. Results from experiments show that the discussed non-functional requirements are adequately met.

@inproceedings{2013_soares,
author={Soares, Luiz Fernando Gomes and Moreno, Marcio Ferreira and Lima,
Guilherme Ferreira and Azevedo, Roberto Gerson de Albuquerque and Araújo,
Eduardo Cruz and Rios, Ricardo and Bartista, Carlos Eduardo},
title={Revisiting the inter and intra media synchronization model of the
{NCL} player architecture.},
booktitle={Proceedings of Media Synchronization Workshop (MediaSync) 2013},
series={MediaSync '13},
year={2013},
location={Nantes, France},
numpages={8},
}

@inproceedings{2013_09_azevedo,
author={Azevedo, Roberto Gerson de Albuquerque and Santos, Rodrigo Costa
Mesquita and Araújo, Eduardo Cruz and Soares, Luiz Fernando Gomes and Soares
Neto, Carlos de Salles},
title={Multimedia authoring based on templates and semi-automatic generated
wizards},
booktitle={Proceedings of the 2013 ACM symposium on Document engineering},
series={DocEng '13},
year={2013},
isbn={978-1-4503-1789-4},
location={Florence, Italy},
pages={205--214},
numpages={10},
url={http://doi.acm.org/10.1145/2494266.2494283},
doi={10.1145/2494266.2494283},
acmid={2494283},
publisher={ACM},
address={New York, NY, USA},
keywords={authoring, multimedia, tal, template-based authoring, wizards},
note={Acceptance ratio: 32\%},
}

@inproceedings{2013_11_azevedo,
author={Azevedo, Roberto Gerson de Albuquerque and Soares, Luiz Fernando
Gomes},
title={ {NCL+Depth}: Extending {NCL} for Stereo/Autostereoscopic 3D
Displays},
booktitle={Proceedings of the 19th Brazilian Symposium on Multimedia and the
Web},
series={WebMedia '13},
year={2013},
isbn={978-1-4503-2559-2},
location={Salvador, Brazil},
pages={185--192},
numpages={8},
url={http://doi.acm.org/10.1145/2526188.2526203},
doi={10.1145/2526188.2526203},
acmid={2526203},
publisher={ACM},
address={New York, NY, USA},
keywords={3DTV, multimedia, nested context language, video-plus-depth},
}

@inproceedings{2013_lima,
author={Lima, Guilherme Augusto Ferreira and Soares, Luiz Fernando Gomes and
Azevedo, Roberto Gerson de Albuquerque and Moreno, Marcio Ferreira},
title={Reducing the Complexity of {NCL} Player Implementations},
booktitle={Proceedings of the 19th Brazilian Symposium on Multimedia and the
Web},
series={WebMedia '13},
year={2013},
isbn={978-1-4503-2559-2},
location={Salvador, Brazil},
pages={297--304},
numpages={8},
url={http://doi.acm.org/10.1145/2526188.2526217},
doi={10.1145/2526188.2526217},
acmid={2526217},
publisher={ACM},
address={New York, NY, USA},
keywords={NCL players, NCL raw profile, web-based players},
}

%%% 2012 %%%

@inproceedings{2012_08_azevedo,
author={Azevedo, Roberto Gerson de Albuquerque and Soares, Luiz Fernando
Gomes},
title={Embedding 3D objects into {NCL} multimedia presentations},
booktitle={Proceedings of the 17th International Conference on 3D Web
Technology},
series={Web3D '12},
year={2012},
isbn={978-1-4503-1432-9},
location={Los Angeles, California},
pages={143--151},
numpages={9},
url={http://doi.acm.org/10.1145/2338714.2338739},
doi={10.1145/2338714.2338739},
acmid={2338739},
publisher={ACM},
address={New York, NY, USA},
keywords={NCL, X3D, declarative languages, digital TV},
}

%%% 2011 %%%

@article{2011_08_soares,
author={Soares, Luiz Fernando Gomes and Azevedo, Roberto Gerson de
Albuquerque and Moreno, Marcio Ferreira},
title={TeleMídia and 3D Hypermedia Research},
journal={SBC Journal on 3D Interactive Systems},
year=2011,
volume={2},
number={2},
issn={2236-3297},
url={http://www.telemidia.puc-rio.br/files/biblio/2011_12_soares.pdf},
}

@inproceedings{2011_08_azevedo,
author={Azevedo, Roberto Gerson de Albuquerque and Neto, Carlos de Salles
Soares and Teixeira, Mário Meireles and Santos, Rodrigo Costa Mesquita and
Gomes, Thiago Alencar},
title={Textual authoring of interactive digital {TV} applications},
booktitle={Proceedings of the 9th international interactive conference on
Interactive television},
series={EuroITV '11},
year={2011},
isbn={978-1-4503-0602-7},
location={Lisbon, Portugal},
pages={235--244},
numpages={10},
url={http://doi.acm.org/10.1145/2000119.2000169},
doi={10.1145/2000119.2000169},
acmid={2000169},
publisher={ACM},
address={New York, NY, USA},
keywords={ginga-ncl, hypermedia authoring, ncl eclipse, nested context
language, textual authoring},
}

@article{2011_01_angelucci,
author={Angeluci, Alan César Belo and Azevedo, Roberto Gerson de Albuquerque
and Soares, Luiz Fernando Gomes},
title={A Comunicação Digital e a Interdisciplinaridade na Produção de
Conteúdo Interativo},
journal={Revista Comunicação Midiática},
year=2011,
month={Jan/Apr},
volume=6,
number=1,
issn={2236-8000},
url={http://www.mundodigital.unesp.br/revista/index.php/comunicacaomidiatica/article/view/58/43},
language={Portuguese},
}

%%% 2010 %%%

@inproceedings{2010_10_santos,
author={Santos, Rodrigo Costa Mesquita and Azevedo, Roberto Gerson de
Albuquerque and Soares Neto, Carlos de Salles and Teixeira, Mário Antônio
Meireles},
title={Correção de Código Semi-Automática em {Nested Context Language}},
booktitle={XVI Simpósio Brasileiro de Sistemas Multimídia e Web (WebMedia
2010)},
year=2010,
month={October},
location={Belo Horizonte, MG, Brasil},
_url={http://www.laws.deinf.ufma.br/~roberto/publications/pdf/2010_10_santos.pdf},
language={Portuguese},
}

@inproceedings{2010_10_sousa,
author={Sousa Júnior, José Geraldo and Azevedo, Roberto Gerson de
Albuquerque and Soares Neto, Carlos de Salles and Soares, Luiz Fernando
Gomes},
title={Estendendo {NCL}: Objetos {NCLua} como Exibidores para Novos Tipos de
Mídia},
booktitle={XVI Simpósio Brasileiro de Sistemas Multimídia e Web (WebMedia
2010)},
year=2010,
month={October},
location={Belo Horizonte, MG, Brasil},
note={I Worshop de TV Digital},
language={Portuguese},
}

@inproceedings{2010_10_lima,
author={Lima, Bruno Seabra and Azevedo, Roberto Gerson de Albuquerque and
Moreno, Marcelo Ferreira and Soares, Luiz Fernando Gomes},
title={Composer 3: Ambiente de Autoria Extensível, Adaptável e
Multiplataforma},
booktitle={XVI Simpósio Brasileiro de Sistemas Multimídia e Web (WebMedia
2010)},
year=2010,
month={October},
location={Belo Horizonte, MG, Brasil},
note={I Worshop de TV Digital},
url={http://www.telemidia.puc-rio.br/files/biblio/2010_10_lima.pdf},
language={Portuguese},
}

@MastersThesis{2010_08_azevedo,
author={Azevedo, Roberto Gerson de Albuquerque},
title={Control and presentation of three-dimensional media objects in {NCL}},
title_ptbr={Suporte ao Controle e à Apresentação de Objetos de Mídia
Tridimensionais em {NCL}},
type={Masters thesis},
school={PUC-Rio},
address={Rio de Janeiro},
year={2010},
month={August},
notes={Apresentada como requisito parcial para obtenção do título Mestre
em Informática},
abstract={O mundo em que vivemos é formado por um espaço fisicamente
tridimensional e é natural que o ser humano busque representá-lo da forma
mais fiel possível, também em ambientes virtuais. Na Web, por exemplo, já
existem vários esforços na busca do suporte a criação de aplicações 3D
interativas de forma declarativa, grande parte deles são baseados nos
conceitos de grafos de cena e grafos de rotas. Grafos de cena têm se tornado
um padrão de modelagem espacial de aplicações tridimensionais por meio de
uma abordagem hierárquica e declarativa. Por sua vez, o comportamento do
grafo de cena usualmente tem sido especificado por meio de grafos de rotas ou
linguagens imperativas. No que se refere à TV Digital Interativa (TVDi), por
outro lado, ainda há muito a ser feito. Nested Context Language (NCL) é a
linguagem declarativa padrão para o sistema de TV Digital Terrestre ISDB-TB
e Recomendação ITU-T para serviços IPTV, que permite a autoria de
documentos hipermídia por meio de uma abordagem simples e expressiva. Embora
NCL não restrinja qualquer tipo de objeto de mídia, na sua versão atual
(3.0), ela trata apenas objetos de mídia bidimensionais, relacionando-os
temporal e espacialmente. Dada a importância de NCL no cenário de TVDi,
esta pesquisa objetiva discutir como tal linguagem pode também controlar
objetos tridimensionais, permitindo a criação de aplicações 3D para TVDi.
Como caso especial, este trabalho discute como NCL pode controlar o
comportamento de objetos 3D compostos representados por grafos de cenas,
discutindo suas vantagens e desvantagens em relação ao uso de grafos de
rotas. Visando testar a proposta deste trabalho, foi adicionado um exibidor
de mídia X3D (linguagem baseada em grafo de cena) à implementação de
referência do Ginga-NCL, responsável por executar aplicações NCL.
Adicionalmente, também é proposta a extensão dos eventos tratados por NCL,
para refletir eventos específicos de ambientes 3D, e a incorporação de
regiões, baseadas em objetos geométricos 3D, à NCL, com o objetivo de
possibilitar a apresentação de objetos de mídia 2D sobre a superfície de
objetos 3D.},
url={http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=16864
1},
language={Portuguese},
}

O mundo em que vivemos é formado por um espaço fisicamente tridimensional e é natural que o ser humano busque representá-lo da forma mais fiel possível, também em ambientes virtuais. Na Web, por exemplo, já existem vários esforços na busca do suporte a criação de aplicações 3D interativas de forma declarativa, grande parte deles são baseados nos conceitos de grafos de cena e grafos de rotas. Grafos de cena têm se tornado um padrão de modelagem espacial de aplicações tridimensionais por meio de uma abordagem hierárquica e declarativa. Por sua vez, o comportamento do grafo de cena usualmente tem sido especificado por meio de grafos de rotas ou linguagens imperativas. No que se refere à TV Digital Interativa (TVDi), por outro lado, ainda há muito a ser feito. Nested Context Language (NCL) é a linguagem declarativa padrão para o sistema de TV Digital Terrestre ISDB-TB e Recomendação ITU-T para serviços IPTV, que permite a autoria de documentos hipermídia por meio de uma abordagem simples e expressiva. Embora NCL não restrinja qualquer tipo de objeto de mídia, na sua versão atual (3.0), ela trata apenas objetos de mídia bidimensionais, relacionando-os temporal e espacialmente. Dada a importância de NCL no cenário de TVDi, esta pesquisa objetiva discutir como tal linguagem pode também controlar objetos tridimensionais, permitindo a criação de aplicações 3D para TVDi. Como caso especial, este trabalho discute como NCL pode controlar o comportamento de objetos 3D compostos representados por grafos de cenas, discutindo suas vantagens e desvantagens em relação ao uso de grafos de rotas. Visando testar a proposta deste trabalho, foi adicionado um exibidor de mídia X3D (linguagem baseada em grafo de cena) à implementação de referência do Ginga-NCL, responsável por executar aplicações NCL. Adicionalmente, também é proposta a extensão dos eventos tratados por NCL, para refletir eventos específicos de ambientes 3D, e a incorporação de regiões, baseadas em objetos geométricos 3D, à NCL, com o objetivo de possibilitar a apresentação de objetos de mídia 2D sobre a superfície de objetos 3D.

@inproceedings{2010_05_santos,
author={Santos, Rodrigo Costa Mesquita and Gomes, T. A. and Azevedo, Roberto
Gerson de Albuquerque and Soares Neto, Carlos de Salles and Teixeira, M. A.
M.},
title={ {NCL Eclipse}: Ferramenta de Autoria Textual para a Linguagem {NCL}},
booktitle={XI Fórum Internacional de Software Livre (FISL 11)},
year={2010},
month={July},
location={Porto Alegre, RS, Brasil},
_url={http://laws.deinf.ufma.br/~roberto/publications/pdf/2010_05_santos.pdf},
language={Portuguese},
}

@article{2009_12_azevedo,
author={Azevedo, Roberto Gerson de Albuquerque and Teixeira, Mário Meireles
and Soares Neto, Carlos de Salles},
title={ {NCL Eclipse}: Ambiente Integrado para o Desenvolvimento de
Aplicações para TV Digital Interativa em {Nested Context Language}},
journal={REIC - Revista Eletrônica de Iniciação Científica},
year=2009,
month={December},
number=4,
issn={1519-8219},
_url={http://laws.deinf.ufma.br/~roberto/publications/pdf/2009_12_azevedo.pdf},
language={Portuguese},
}

@inproceedings{2009_11_angelucci,
author={Angelucci, Alan César Belo and Azevedo, Roberto Gerson de
Albuquerque and Soares, Luiz Fernando Gomes},
title={O Uso da Linguagem Declarativa do {Ginga-NCL} na Construção de
Conteúdos Audiovisuais Interativos: A Experiência do "Roteiros do Dia"},
booktitle={I Simpósio Internacional de Televisão Digital (SIMTVD)},
pages={},
publisher={},
year=2009,
month={November},
location={Bauru, SP, Brazil},
url={http://www.telemidia.puc-rio.br/files/biblio/2009_11_angeluci.pdf},
language={Portuguese},
}

@incollection{2009_10_santanna,
author={Santa'Anna, Francisco and Soares Neto, Carlos de Salles and Azevedo,
Roberto Gerson de Albuquerque and Barbosa, Simone Diniz Junqueira},
title={Desenvolvimento de Aplicações Declarativas para TV Digital no
Middleware Ginga com Objetos Imperativos Lua},
booktitle={},
pages={},
publisher={},
year=2009,
editor={},
location={Fortaleza, CE, Brazil},
url={http://www.telemidia.puc-rio.br/files/biblio/2009_10_santanna.pdf},
language={Portuguese},
}

@inproceedings{2009_10_lima,
author={Lima, Bruno Seabra and Azevedo, Roberto Gerson de Albuquerque and
Soares Neto, Carlos de Salles},
title={Autoria de Documentos Multimídia Baseada na Identificação e
Preenchimento de Estruturas Recorrentes},
booktitle={XV Simpósio Brasileiro de Sistemas Multimídia e Web (WebMedia
2009)},
year=2009,
month={October},
location={Fortaleza, CE, Brazil},
url={http://www.telemidia.puc-rio.br/files/biblio/2009_10_lima.pdf},
language={Portuguese},
}

@inproceedings{2009_10_azevedo,
author={Azevedo, Roberto Gerson de Albuquerque and Lima, Bruno Seabra and
Soares Neto, Carlos de Salles and Teixeira, Mário Meireles},
title={Uma Abordagem para Autoria Textual de Documentos Hipermídia Baseada
no Uso de Visualização Programática e Navegação Hipertextual},
booktitle={XV Simpósio Brasileiro de Sistemas Multimídia e Web (WebMedia
2009)},
year=2009,
month={October},
location={Fortaleza, CE, Brazil},
url={http://www.telemidia.puc-rio.br/files/biblio/2009_10_azevedo.pdf},
language={Portuguese},
}

@inproceedings{2009_05_azevedo,
author={Azevedo, Roberto Gerson de Albuquerque and Teixeira, Mario Meireles
and Soares Neto, Carlos de Salles},
title={ {NCL Eclipse}: Ambiente Integrado para o Desenvolvimento de
Aplicações Interativas em {Nested Context Language}},
booktitle={Salão de Ferramentas do Simpósio Brasileiro de Redes de
Computadores (SBRC)},
year=2009,
month={May},
url={http://www.lbd.dcc.ufmg.br/colecoes/sbrc/2009/087.pdf},
language={Portuguese},
}

%%% 2008 %%%

@inproceedings{2008_06_araujo,
author={Araújo, Eduardo Cruz and Azevedo, Roberto Gerson de Albuquerque and
Soares Neto, Carlos de Salles},
title={ {NCL}-validator: um processo de validação sintática e semântica
de documentos multimídia {NCL}},
booktitle={II Jornada de Informática do Maranhão},
year=2008,
month={June},
note={Best Paper Award},
_url={http://www.laws.deinf.ufma.br/~roberto/publications/pdf/2008_06_araujo.pdf},
language={Portuguese},
}

%%% 2006 %%%

@inproceedings{2006_06_azevedo,
author={Azevedo, Roberto Gerson de Albuquerque and Teixeira, Mário Meireles
and Araújo, Eduardo Cruz},
title={Deinf Media Center: Infra-Estrutura para Armazenamento e
Distribuição de Conteúdo Multimídia Streaming},
booktitle={I Jornada de Informática do Maranhão},
year=2006,
month={November},
language={Portuguese},
}