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A System-On-Chip Platform for HRTF-Based Realtime Spatial Audio Rendering

Authors:
Wolfgang Fohl
Jürgen Reichardt
Jan Kuhr

Keywords: Mixed-reality audio; realtime HRTF interpolation; system-on-chip;

Abstract:
A system-on-chip platform for realtime rendering of spatial audio signals is presented. The system is based on a Xilinx Virtex-5 ML507 FPGA platform. On the chip an embedded microblaze microprocessor core and FIR filters are configured. Filtering is carried out in the FPGA hardware for performance reasons whereas the signal management is performed on the embedded processor. The azimuth and elevation angles of a virtual audio source relative to the listener's head can be modified in real time. The system is equipped with a compass sensor to track the head orientation. This data is used to transform the room related coordinates of the virtual audio source to the head related coordinates of the listener, so that a fixed position of the virtual sound source relative to the room can be attained regardless of the listener's head rotation. Head related transfer functions (HRTF) were sampled in steps of 30° for azimuth and elevation. Interpolation for intermediate angles is done by either interpolating between the coefficients of the measured HRTFs at the four adjacent angles (azimuth and elevation), or by feeding the audio signal through the corresponding four filters, and mixing the outputs together. In the latter case the required four filter processes per output stereo channel do not result in longer computing time because of the true parallel operation of the FPGA system. The system output is identical to the output of a corresponding Matlab prototype.

Pages: 45 to 50

Copyright: Copyright (c) IARIA, 2010

Publication date: November 21, 2010

Published in: conference

ISSN: 2308-4162

ISBN: 978-1-61208-110-6

Location: Lisbon, Portugal

Dates: from November 21, 2010 to November 26, 2010