Loading...
12 results
Search Results
Now showing 1 - 10 of 12
- 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.
- User preference on artificial reverberation and delay time parameters with applications to automatic multitrack mixingPublication . Pestana, Pedro Duarte; Reiss, Joshua D.; Barbosa, ÁlvaroIn this work we present the results of two subjective tests that strive to evaluate user preference on artificial reverb and delay time, while trying to relate choice to musical tempo and other low-level explaining factors. The need to understand and explain these options through common practice arises from the lack of grounding that is needed to establish a mapping of musical features to audio control parameters. This mapping is crucial for the development of intelligent production systems, namely automatic audio mixers, which has been trending over the last few years. Results show there is a conclusive relationship between musical tempo and delay time preference as described by users, but are unsatisfactory in explaining reverb time settings. In this latter aspect this work has, however, uncovered some hints on how to proceed in order to quantify the phenomenon.
- 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.
- 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.
- User preference on artificial reverberation and delay time parametersPublication . Pestana, Pedro D.; Reiss, Joshua D.; Barbosa, ÁlvaroIt is a common belief that settings of artificial reverb and delay time in music production are strongly linked to musical tempo and related factors. But this relationship, if in existence, is not yet understood. We present the results of two subjective tests that evaluate user preference of young adults with formal training in audio engineering on artificial reverb and delay time, while trying to relate choice to tempo and other low-level explaining factors. Results show there is a conclusive relationship between musical tempo and delay time preference as described by users. Reverb time setting preference, however, cannot be explained in such a strong manner. In this latter aspect the present work has nevertheless uncovered some ideas on how to proceed in order to quantify the phenomenon.
- Lindenmeyer systems and the harmony of fractalsPublication . Pestana, PedroAn 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.
- Intelligent multitrack dynamic range compressionPublication . Ma, Zheng; Man, Brecht de; Pestana, Pedro D. L.; Black, Dawn A. A.; Reiss, Joshua D.We present an intelligent approach to multitrack dynamic range compression where all parameters are configured automatically based on side-chain feature extraction from the input signals. A method of adjustment experiment to explore how audio engineers set the ratio and threshold is described. We use multiple linear regression to model the relationship between different features and the experimental results. Parameter automations incorporate control assumptions based on this experiment and those derived from mixing literature and analysis. Subjective evaluation of the intelligent system is provided in the form of a multiple stimulus listening test where the system is compared against a no-compression mix, two human mixes, and an alternative approach. Results showed that mixes devised by our system are able to compete with or outperform manual mixes by semi-professionals under a variety of subjective criteria.
- Sir Pinski rides againPublication . Gomes, Maria Ivette; Pestana, Dinis; Pestana, PedroThe 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.
- 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.
- 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.