Extracting and Re-rendering Structured Auditory Scenes from Field Recordings

International audienceWe present an approach to automatically extract and re-render a structured auditory scene from field recordings obtained with a small set of microphones, freely positioned in the environment. From the recordings and the calibrated position of the microphones, the 3D location of various auditory events can be estimated together with their corresponding content. This structured description is reproduction-setup independent. We propose solutions to classify foreground, well-localized sounds and more diffuse background ambiance and adapt our rendering strategy accordingly. Warping the original recordings during playback allows for simulating smooth changes in the listening point or position of sources. Comparisons to reference binaural and B-format recordings show that our approach achieves good spatial rendering while remaining independent of the reproduction setup and offering extended authoring capabilities

Les descripteurs d'un son Librairie Matlab SPL et fichiers de descriptions ".sig""

Le traitement du signal audio rapide travaille avec des descriptions compactes des sons plutôt qu'avec les sons eux-mêmes. Dans une première partie nous introduisons cette notion de description et nous proposons un état de l'art des différents types de description utilisés. Ces descriptions incorporent le plus souvent des quantités telles que l'énergie ou le spectre de puissance à court-terme. Cependant, énergie et puissance sont des concepts qui sont souvent confondus ou mal interprétés, et leur définition dépend des conventions de calcul qui ont été choisies pour les signaux numérisés. Nous rappelons dans une deuxième partie les définitions théoriques (physiques) de ces concepts, et nous proposons nos propres conventions de calcul. Nous définisson alors un ensemble de formules pour le calcul exact (i.e. cohérent avec leur définition physique) de l'énergie, de la puissance ou de la valeur RMS en dB SPL. Ces définitions sont implémentées dans une librairie Matlab (SPL) qui sert à calculer les descripteurs d'un fichier son, et les incorpore dans un fichier de description dont nous avons défini le format (.sig). La dernière partie de ce rapport décrit la syntaxe de ces fonctions. Finalement, la troisième partie de ce rapport décrit la stucture des fichiers .sig

Efficient 3D Audio Processing on the GPU

International audienceAudio processing applications are among the most computeintensive and often rely on additional DSP resources for realtime performance. However, programmable audio DSPs are in general only available to product developers. Professional audio boards with multiple DSPs usually support specific effects and products while consumer "game-audio" hardware still only implements fixed-function pipelines which evolve at a rather slow pace. The widespread availability and increasing processing power of GPUs could offer an alternative solution. GPU features, like multiply-accumulate instructions or multiple execution units, are similar to those of most DSPs [3]. Besides, 3D audio rendering applications require a significant number of geometric calculations, which are a perfect fit for the GPU. Our feasibility study investigates the use of GPUs for efficient audio processing

Breaking the 64 spatialized sources barrier

International audienceSpatialized soundtracks and sound-effects are standard elements of today's video games. However, although 3D audio modeling and content creation tools (e.g., Creative Lab's EAGLE [4]) provide some help to game audio designers, the number of available 3D audio hardware channels remains limited, usually ranging from 16 to 64 in the best case. While one can wonder whether more hardware channels are actually required, it is clear that large numbers of spatialized sources might be needed to render a realistic environment. This problem becomes even more significant if extended sound sources are to be simulated: think of a train for instance, which is far too long to represented as a point source. Since current hardware and APIs implement only point-source models or limited extended source models [2,3,5], a large number of such sources would be required to achieve a realistic effect (view Example1). Finally, 3D-audio channels might also be used for restitution-independent representation of surround music tracks, leaving the generation of the final mix to the audio rendering API but requiring the programmer to assign some of the precious 3D channels to the soundtrack. Also, dynamic allocation schemes currently available in game APIs (e.g. Direct Sound 3D [2]) remain very basic. As a result, game audio designers and developers have to spend a lot of effort to best-map the potentially large number of sources to the limited number of channels. In this paper, we provide some answers to this problem by reviewing and introducing several automatic techniques to achieve efficient hardware mapping of complex dynamic audio scenes in the context of currently available hardware resources

Prioritizing signals for selective real-time audio processing

Presented at the 11th International Conference on Auditory Display (ICAD2005)This paper studies various priority metrics that can be used to progressively select sub-parts of a number of audio signals for realtime processing. In particular, five level-related metrics were examined: RMS level, A-weighted level, Zwicker and Moore loudness models and a masking threshold-based model. We conducted a pilot subjective evaluation study aimed at evaluating which metric would perform best at reconstructing mixtures of various types (speech, ambient and music) using only a budget amount of original audio data. Our results suggest that A-weighting performs the worst while results obtained with loudness metrics appear to depend on the type of signals. RMS level offers a good compromise for all cases. Our results also show that significant sub-parts of the original audio data can be omitted in most cases, without noticeable degradation in the generated mixtures, which validates the usability of our selective processing approach for real-time applications. In this context, we successfully implemented a prototype 3D audio rendering pipeline using our selective approach

A User-Centered Approach on Combining Realism and Interactivity in Virtual Environments

International audienceIn this paper we describe a project that adopts a usercentered approach in the design of virtual environments (VEs) with enhanced realism and interactivity, guided by real-world applications in the areas of urban planning/ architecture and cultural heritage education. In what concerns realism, we introduce an image-based 3D capture process, where realistic models are created from photographs and subsequently displayed in a VR system using a high-quality, view-dependent algorithm. The VE is further enhanced using advanced vegetation and shadow display algorithms as well as 3D sound. A high degree of interactivity is added, allowing users to build and manipulate elements of the VEs according to their needs, as specified through a user task analysis and scenario-based approach which is currently being evaluated. This work is developed as part of the EU-funded research project CREATE

Image-based Techniques for the Creation and Display of Photorealistic Interactive Virtual Environments

International audienceIn this paper we introduce an image-based 3D capture process for the creation and display of photorealistic virtual environments (VEs). The resulting VEs aim to realistically recreate existing real-world scenes that can be displayed in a range of immersive VR systems using a high-quality, view-dependent algorithm and further enhanced using advanced vegetation, shadow display algorithms and 3D sound. The scenes, an archaeological site and an urban environment, were chosen according to real-world applications in the areas of urban planning/architecture and cultural heritage education. The users in each case are able to reconstruct or manipulate elements of the VEs according to their needs, as these have been specified through a detailed user requirements survey. Furthermore, a user task analysis and scenario-based approach has been adopted for the design of the virtual prototypes and the evaluation, which is currently underway. This work is being developed in the context of the EU-funded research project CREATE and the first examples of the prototype system in use are described and demonstrated in this paper

UMA CONVERSA-VIAGEM:: ENTRE O PASSADO E O FUTURO DO ENSINO DE FILOSOFIA

Trata-se da transcrição de uma conversa-viagem ocorrida em 2008, após o “VIII Simpósio Sul-Brasileiro sobre o ensino de filosofia: filosofia, formação docente e cidadania”. Nesta conversa estão expressas experiências políticas, filosóficas e pedagógicas vividas no Brasil, na Argentina e no Uruguai por professores de filosofia, importantes personagens do cenário latino-americano no que diz respeito à formação de professores e à luta pela inclusão da Filosofia nos currículos do Ensino Médio brasileiro. Emmanuel Appel conta, em detalhes, o que se passou nos caminhos e descaminhos dos projetos de inclusão da disciplina, bem como retoma 37 anos do movimento em defesa da formação filosófica dos jovens brasileiros. Mauricio Langón, responsável pelo registro dessa conversa, age como um jornalista provocador e instiga Sílvio Gallo a posicionar-se frente à especificidade da Filosofia e sua função na escola, assim como aos desafios que temos pela frente com a sua inclusão (a conversa se deu duas semanas antes de o projeto ser sancionado por José de Alencar, presidente em exercício) ”“ tudo que ele afirma segue sendo desafio para nós. Langón chama Laura Agratti para a conversa e põe em questão a formação daqueles que vão ensinar aos jovens. Na oportunidade, ela trata das diferenças entre os casos brasileiro e argentino, põe em questão uma possível proposta curricular hegemônica, trata da importância do perguntar e dos problemas nas aulas de filosofia e, ao lado disso, questiona os usos da História da Filosofia. Por fim, antes de chegar ao destino, Langón relata uma experiência e lança para nós, quatro anos depois de suas palavras, o problema da formação que merece ser pensado

Acceptability of Condom Promotion and Distribution Among 10-19 Year-Old Adolescents in Mpwapwa and Mbeya Rural Districts, Tanzania.

\ud The HIV/AIDS pandemic remains a leading challenge for global health. Although condoms are acknowledged for their key role on preventing HIV transmission, low and inappropriate use of condoms persists in Tanzania and elsewhere in Africa. This study assesses factors affecting acceptability of condom promotion and distribution among adolescents in Mpwapwa and Mbeya rural districts of Tanzania. Data were collected in 2011 as part of a larger cross-sectional survey on condom use among 10-19 year-olds in Mpwapwa and Mbeya rural districts of Tanzania using a structured questionnaire. Associations between acceptability of condom promotion and distribution and each of the explanatory variables were tested using Chi Square. Multivariate logistic regression model was used to examine independent predictors of the acceptability of condom promotion and distribution using STATA (11) statistical software at 5% significance level. Mean age of the 1,327 adolescent participants (50.5% being males) was 13.5 years (SD = 1.4). Acceptance of condom promotion and distribution was found among 37% (35% in Mpwapwa and 39% in Mbeya rural) of the adolescents. Being sexually active and aged 15-19 was the strongest predictor of the acceptability of condom promotion and distribution (OR = 7.78, 95% CI 4.65-12.99). Others were; not agreeing that a condom is effective in preventing transmissions of STIs including HIV (OR = 0.34, 95% CI 0.20-0.56), being a resident of Mbeya rural district (OR = 1.67, 95% CI 1.28-2.19), feeling comfortable being seen by parents/guardians holding/buying condoms (OR = 2.20, 95% CI 1.40-3.46) and living with a guardian (OR = 1.48, 95% CI 1.08-2.04). Acceptability of condom promotion and distribution among adolescents in Mpwapwa and Mbeya rural is low. Effect of sexual activity on the acceptability of condom promotion and distribution is age-dependent and was the strongest. Feeling comfortable being seen by parents/guardians buying or holding condoms, perceived ability of condoms to offer protection against HIV/AIDS infections, district of residence and living arrangements also offered significant predictive effect. Knowledge of these factors is vital in designing successful and sustainable condom promotion and distribution programs in Tanzania.\u