Browsing by Author "Pestana, Pedro Duarte"
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- A cross-adaptive dynamic spectral panning techniquePublication . Pestana, Pedro Duarte; Reiss, Joshua D.This work presents an algorithm that is able to achieve novel spatialization effects on multitrack audio signals. It relies on a crossadaptive framework that dynamically maps the azimuth positions of each track's time-frequency bins with the goal of reducing masking between source signals by dynamically separating them across space. The outputs of this system are compared to traditional panning strategies in subjective evaluation, and it is seen that scores indicate it performs well as a novel effect that can be used in live sound applications and creative sound design or mixing.
- Cross-adaptive polarity switching strategies for optimization of audio mixesPublication . Pestana, Pedro Duarte; Reiss, Joshua D.; Barbosa, ÁlvaroCrest factor is an often overlooked part of audio production, yet it acts as an important limit to overall loudness. We propose a technique to optimize relative polarities in order to yield the lowest possible peak value. We suggest this is a way of addressing loudness maximization that is more sonically transparent than peak limiting or compression. We also explore additional uses that polarity analysis may have in the context of mixing audio. Results show this is a fairly e ective strategy, with average crest factor reductions of 3 dB, resulting in equivalent values for loudness enhancement. While still not comparable to the amount of reduction peak limiters are typically used for, the approach is seen as more transparent via subjective evaluation, through a multi-stimulus test.
- Intelligent audio production strategies informed by best practicesPublication . Pestana, Pedro Duarte; Reiss, Joshua D.The main focus of this article is to explore and investigate the fundamental constraints that should be at the basis of algorithm development in intelligent audio production systems. Through mix analysis and grounded theory strategies, a best-practices framework on the craft of mixing is sought out. Findings, while not to be taken as dogmatic, give a clear indication of preferred implementation strategies, and show what still needs to be done to fully understand the technical choices that audio mixing has incorporated throughout its history.
- Lindenmayer systems and the harmony of fractalsPublication . Pestana, Pedro DuarteAn interactive musical application is developed for realtime improvisation with a machine based on Lindenmeyer-systems. This has been used on an installation whose goal is to draw the attention of unexperienced users to the wealth of realtime applications in computer music. Issues on human computer interaction and improvisation grammars had to be dealt with, as well as probabilistic strategies for musical variation. The choice of L-systems as a basis for machine composition is a consequence of their ability to create results that easily have aesthetic appeal, both in the realms of sound and image.
- Loudness measurement of multitrack audio content using modifcations of ITU-R BS.1770Publication . Pestana, Pedro Duarte; Reiss, Joshua D.; Barbosa, ÁlvaroThe recent loudness measurement recommendations by the ITU and the EBU have gained widespread recognition in the broadcast community. The material it deals with is usually full-range mastered audio content, and its applicability to multitrack material is not yet clear. In the present work we investigate how well the evaluated perception of single track loudness agrees with the measured value as de ned by ITU-R BS.1770. We analyze the underlying features that may be the cause for this disparity and propose some parameter alterations that might yield better results for multitrack material with minimal modi cation to their rating of broadcast content. The best parameter sets are then evaluated by a panel of experts in terms of how well they produce an equal-loudness multitrack mix, and are shown to be signi cantly more successful.
- Nota de aberturaPublication . Pestana, Pedro Duarte
- Philip Glass' Façades: a case study on the complexity of music scoresPublication . Pestana, Pedro Duarte; Pestana, DinisRepetitive structures in the soprano saxophones, violas/synthesizer and violoncelli in the full score of Philip Glass' Fa cades [4] are investigated assimilating similar music bars with the axial-diagonal self-a ne cartoons as de ned by Mandelbrot [7], [8] to construct very general multi-fractals. Transition matrices of order 1 Markov chains are used to simulate surrogates of phrases of the same piece, to investigate whether in this minimalist setting we obtain (i) an exact reproduction of the original, or (ii) something that though di erent sounds a pleasant variation.
- Sir Pinski Rides AgainPublication . Gomes, Maria Ivette; Pestana, Dinis; Pestana, Pedro DuarteThe iterative procedure of removing “almost everything” from a triangle ultimately leading to the Sierpinski's gasket S is well-known. But what is in fact left when almost everything has been taken out? Using the Sir Pinski's game described by Schroeder [4], we identify two dual sets of invariant points in this exquisite game, and from these we identify points left over in Sierpinski gasket. Our discussion also shows that the chaos game does not generate the Sierpinski gasket. It generates an approximation or, at most, a subset of S.
- Spectral characteristics of popular commercial recordings 1950-2010Publication . Pestana, Pedro Duarte; Ma, Zheng; Reiss, Joshua D.; Barbosa, Álvaro; Black, Dawn A. A.In this work, the long-term spectral contours of a large dataset of popular commercial recordings were analyzed. The aim was to analyze overall trends, as well as yearly and genre-speci c ones. A novel method for averaging spectral distributions is proposed, which yields results that are prone to comparison. With it, we found out that there is a consistent leaning towards a target equalization curve that stems from practices in the music industry, but also to some extent mimics natural, acoustic spectra of ensembles.
- The Smart Stage: Designing 3D interaction metaphors for immersive and ubiquitous music systemsPublication . Bernardo, Francisco; Pestana, Pedro Duarte; Martins, Luís G.This conceptual paper describes a work in progress in the process of design and implementation of the Smart Stage, an interactive music system prototype for collaborative musical creativity in immersive and ubiquitous environments. This system is intended to have a low entry barrier, thus more forgiving to users with lesser experience or knowledge in music, and it is designed with affordances to support intuitive progress in improvisational performance in a collaborative setting. We present a preliminary technical overview of the system and a first case study of a 3D interaction metaphor for granular synthesis, developed for this environment.