Eliminating aliasing caused by discontinuities using integrals of the sinc function

Fabian Esqueda Flores, Stefan Bilbao, Vesa Välimäki

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Abstract

A study on the limits of bandlimited correction functions used to eliminate aliasing in audio signals with discontinuities is presented. Trivial sampling of signals with discontinuities in their waveform or their derivatives causes high levels of aliasing distortion due to the infinite bandwidth of these discontinuities. Geometrical oscillator waveforms used in subtractive synthesis are a common example of audio signals with these characteristics. However, discontinuities may also be introduced in arbitrary signals during operations such as signal clipping and rectification. Several existing techniques aim to increase the perceived quality of oscillators by attenuating aliasing sufficiently to be inaudible. One family of these techniques consists on using the bandlimited step (BLEP) and ramp (BLAMP) functions to quasi-bandlimit discontinuities. Recent work on antialiasing clipped audio signals has demonstrated the suitability of the BLAMP method in this context. This work evaluates the performance of the BLEP, BLAMP, and integrated BLAMP functions by testing whether they can be used to fully bandlimit aliased signals. Of particular interest are cases where discontinuities appear past the first derivative of a signal, like in hard clipping. These cases require more than one correction function to be applied at every discontinuity. Results obtained show that if sufficiently many samples are corrected at each discontinuity, aliasing can be virtually eliminated while preserving the spectral envelope of the signal. This work extends the understanding of the BLEP, BLAMP, and integrated BLAMP functions as antialiasing tools.
Original languageEnglish
Title of host publicationProceedings of the International Symposium on Musical and Room Acoustics
Subtitle of host publicationISMRA 2016
EditorsFederico Miyara
PublisherAsociación de Acústicos Argentinos
Number of pages10
ISBN (Electronic)978-987-24713-8-5
Publication statusPublished - 2016
MoE publication typeA4 Article in a conference publication
EventInternational Symposium on Musical and Room Acoustics - Buenos Aires, Argentina
Duration: 11 Sep 201613 Sep 2016
http://www.ismra2016.org.ar/

Conference

ConferenceInternational Symposium on Musical and Room Acoustics
Abbreviated titleISMRA
CountryArgentina
CityBuenos Aires
Period11/09/201613/09/2016
Internet address

Keywords

  • Antialiasing
  • audio signal processing
  • signal synthesis

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    Esqueda Flores, F., Bilbao, S., & Välimäki, V. (2016). Eliminating aliasing caused by discontinuities using integrals of the sinc function. In F. Miyara (Ed.), Proceedings of the International Symposium on Musical and Room Acoustics: ISMRA 2016 Asociación de Acústicos Argentinos.