User-Experience with Haptic Feedback Technologies and Text Input in Interactive Multimedia Devices

Remote control devices are commonly used for interaction with multimedia equipment and applications (e.g., smart TVs, gaming, etc.). To improve conventional keypad-based technologies, haptic feedback and user input capabilities are being developed for enhancing the UX and providing advanced functionalities in remote control devices. Although the sensation provided by haptic feedback is similar to mechanical push buttons, the former offers much greater flexibility, due to the possibility of dynamically choosing different mechanical effects and associating different functions to each of them. However, selecting the best haptic feedback effects among the wide variety that is currently enabled by recent technologies, remains a challenge for design engineers aiming to optimise the UX. Rich interaction further requires text input capability, which greatly influences the UX. This work is a contribution towards UX evaluation of remote control devices with haptic feedback and text input. A user evaluation study of a wide variety of haptic feedback effects and text input methods is presented, considering different technologies and different number of actuators on a device. The user preferences, given by subjective evaluation scores, demonstrate that haptic feedback has undoubtedly a positive impact on the UX. Moreover, it is also shown that different levels of UX are obtained, according to the technological characteristics of the haptic actuators and how many of them are used on the device.info:eu-repo/semantics/publishedVersio

Error concealment-aware encoding for robust video transmission

In this paper an error concealment-aware encoding scheme is proposed to improve the quality of decoded video in broadcast environments prone to transmission errors and data loss. The proposed scheme is based on a scalable coding approach where the best error concealment (EC) methods to be used at the decoder are optimally determined at the encoder and signalled to the decoder through SEI messages. Such optimal EC modes are found by simulating transmission losses followed by a lagrangian optimisation of the signalling rate - EC distortion cost. A generalised saliency-weighted distortion is used and the residue between coded frames and their EC substitutes is encoded using a rate-controlled enhancement layer. When data loss occurs the decoder uses the signalling information is used at the decoder, in case of data loss, to improve the reconstruction quality. The simulation results show that the proposed method achieves consistent quality gains in comparison with other reference methods and previous works. Using only the EC mode signalling, i.e., without any residue transmitted in the enhancement layer, an average PSNR gain up to 2.95 dB is achieved, while using the full EC-aware scheme, i.e., including residue encoded in the enhancement layer, the proposed scheme outperforms other comparable methods, with PSNR gain up to 3.79 dB

A two-stage approach for robust HEVC coding and streaming

The increased compression ratios achieved by the High Efficiency Video Coding (HEVC) standard lead to reduced robustness of coded streams, with increased susceptibility to network errors and consequent video quality degradation. This paper proposes a method based on a two-stage approach to improve the error robustness of HEVC streaming, by reducing temporal error propagation in case of frame loss. The prediction mismatch that occurs at the decoder after frame loss is reduced through the following two stages: (i) at the encoding stage, the reference pictures are dynamically selected based on constraining conditions and Lagrangian optimisation, which distributes the use of reference pictures, by reducing the number of prediction units (PUs) that depend on a single reference; (ii) at the streaming stage, a motion vector (MV) prioritisation algorithm, based on spatial dependencies, selects an optimal sub-set of MVs to be transmitted, redundantly, as side information to reduce mismatched MV predictions at the decoder. The simulation results show that the proposed method significantly reduces the effect of temporal error propagation. Compared to the reference HEVC, the proposed reference picture selection method is able to improve the video quality at low packet loss rates (e.g., 1%) using the same bitrate, achieving quality gains up to 2.3 dB for 10% of packet loss ratio. It is shown, for instance, that the redundant MVs are able to boost the performance achieving quality gains of 3 dB when compared to the reference HEVC, at the cost using 4% increase in total bitrate

Reference picture selection using checkerboard pattern for resilient video coding

The improved compression efficiency achieved by the High Efficiency Video Coding (HEVC) standard has the counter-effect of decreasing error resilience in transmission over error-prone channels. To increase the error resilience of HEVC streams, this paper proposes a checkerboard reference picture selection method in order to reduce the prediction mismatch at the decoder in case of frame losses. The proposed approach not only allows to reduce the error propagation at the decoder, but also enhances the quality of reconstructed frames by selectively constraining the choice of reference pictures used for temporal prediction. The underlying approach is to increase the amount of accurate temporal information at the decoder when transmission errors occur, to improve the video quality by using an efficient combination of diverse motion fields. The proposed method compensates for the small loss of coding efficiency at frame loss rates as low as 3%. For a single frame-loss event the proposed method can achieve up to 2 dB of gain in the affected frames and an average quality gain of 0:84 dB for different error prone conditions

A robust video encoding scheme to enhance error concealment of intra frames

In this paper a robust encoding scheme is proposed to improve the visual quality of HEVC decoded video when intra frames are lost along the streaming path. For this purpose, the encoding process includes frame loss simulation and subsequent error concealment, to find the most efficient method that should be used by a decoder to recover lost intra frames. In this novel scheme, each image is divided into partitions, which are associated with the error concealment method that achieves the lowest distortion. Then this information is signalled to the decoder through SEI messages in the coded stream. In order to efficiently use the signalling overhead, rate-distortion optimisation is used to achieve the best trade-off between the number of transmitted symbols and distortion of reconstructed frames. Experimental results show the effectiveness of the proposed method to enhance the quality of reconstructed intra frames under different packet loss ratios (PLR). For PLR=10%, the robust coding scheme is able to improve the average PSNR of all frames affected by errors, up to 1.50 dB and 3.44 dB in Low-Delay and Random-Access configurations respectively, at a maximum overhead cost of 0.24%

Reference picture selection using checkerboard pattern for resilient video coding

The improved compression efficiency achieved by the High Efficiency Video Coding (HEVC) standard has the counter-effect of decreasing error resilience in transmission over error-prone channels. To increase the error resilience of HEVC streams, this paper proposes a checkerboard reference picture selection method in order to reduce the prediction mismatch at the decoder in case of frame losses. The proposed approach not only allows to reduce the error propagation at the decoder, but also enhances the quality of reconstructed frames by selectively constraining the choice of reference pictures used for temporal prediction. The underlying approach is to increase the amount of accurate temporal information at the decoder when transmission errors occur, to improve the video quality by using an efficient combination of diverse motion fields. The proposed method compensates for the small loss of coding efficiency at frame loss rates as low as 3%. For a single frame-loss event the proposed method can achieve up to 2 dB of gain in the affected frames and an average quality gain of 0:84 dB for different error prone conditions

Computador/internet como instrumentos culturais de aprendizagem na formação de professores em diferentes contextos educacionais de uma uiversidade federal

-Este trabalho relata a pesquisa “Computador/internet como instrumentos culturais de aprendizagem na formação de professores em diferentes contextos educacionais de uma universidade federal”, em desenvolvimento de 2007 a 2010 financiada pelo CNPq e FAPEMIG. Esta pesquisa pretende compreender como, em diferentes contextos educacionais de uma universidade federal, em cursos de formação inicial de professores e no processo de formação continuada de professores do Colégio de Aplicação dessa instituição, se processa a incorporação do computador/internet como instrumentos culturais de aprendizagem na prática pedagógica. Orientada pela perspectiva histórico-cultural, se subdivide em 5 sub-projetos. O sub-projeto I, já concluído, focalizou a utilização do infocentro da Faculdade de Educação por alunos da Pedagogia, trabalhando com Grupos Focais Reflexivos como instrumento metodológico. Observou-se que o uso do computador/internet pelos alunos de Pedagogia é ainda tímido, não integrado à prática pedagógica e sua frequência ao infocentro não é significativa. Através do discurso dos alunos, percebeu-se que os professores não utilizam o computador/internet em suas disciplinas. No entanto,ao final do trabalho ocorreram algumas mudanças neste contexto como a inclusão de disciplinas envolvendo a Informática e a Educação na reforma curricular do curso de Pedagogia. Este fato, aliado a uma reforma administrativa da Faculdade de Educação, na qual foi criada a coordenação de redes digitais na educação podem ser considerados como um avanço em direção ao trabalho com as tecnologias digitais na formação inicial de professores O sub-projeto II, em andamento, busca compreender o uso que os alunos do Colégio de Aplicação fazem do computador/internet em seu cotidiano e que sentidos estão construindo em relação ao uso dessas tecnologias no infocentro implantado em sua escola. O sub-projeto IV, também em andamento, busca compreender como professores de Ensino Fundamental e Médio desse colégio utilizam o computador e a internet, em suas salas de aula. Foi realizado um estudo piloto com um levantamento da realidade da escola incluindo uma observação do infocentro e de uma sala de computadores denominada sala de telemática. Percebeu-se que o Infocentro é muito procurado pelos alunos para acessarem o site de relacionamentos Orkut e sites de jogos, funcionando para seus usuários como forma de entretenimento e não como um espaço para atividades relacionadas às disciplinas escolares e sua aprendizagem. Na sala de telemática acompanhamos o trabalho desenvolvido com o apoio de computadores por um grupo de professores em suas aulas de matemática. Foram realizadas observações, entrevista com o coordenador e notas de campo expandidas. Analisamos a evolução histórica desta sala e buscamos compreender como nela os professores atuam com seus alunos na utilização do cumputador e da internet. Os sub-projetos III e V pertencem à proxima etapa da pequisa