Attribution

Original work

The spectral bandwidth extension algorithm implemented here is by:

Jeffrey N. Chadwick (Cornell University, at the time of publication)
Doug L. James (Cornell University, at the time of publication; now Stanford University)

Published in:

Jeffrey N. Chadwick and Doug L. James, “Animating Fire with Sound,” ACM Transactions on Graphics (SIGGRAPH 2011), 30(4), August 2011.

Project page (canonical reference): https://www.cs.cornell.edu/projects/Sound/fire/

Paper PDF: https://www.cs.cornell.edu/projects/Sound/fire/FireSound2011.pdf

Reference implementation

The Python and JavaScript code in this repository is a faithful port of the Matlab reference implementation released by the authors at the URL above (bandwidth_extension.zip / bandwidth_extension.tar.gz). All algorithm design choices, parameter defaults, and numerical details follow that implementation. Differences from the released Matlab are documented in docs/ALGORITHM.md.

License

The original Matlab implementation is distributed under the BSD 2-Clause License (see LICENSE). All derivative source files in this repository carry forward the original copyright notice and disclaimer.

Additional code (the Python and JavaScript ports, the browser demo, the test harness) is also licensed under the BSD 2-Clause License, with attribution to the original authors required by the same terms.

Test signal data

The five .vector files in srcOrig/work/ are the low-frequency outputs of physically based flame simulations, produced by the original authors and distributed with their code release. They are used here unmodified (re-encoded as Float32 for browser delivery) for educational demonstration.

Browser demo context

This browser demo was developed for the course CS 448Z (Physically Based Animation and Sound) at Stanford University, Spring 2026, taught by Doug L. James. It is intended as an educational exploration of the algorithm and is not affiliated with or endorsed by the original publication beyond the use of its released code and data.

Vendored libraries

fft.js by Fedor Indutny (github.com/indutny/fft.js), MIT License. See fft.js at the project root for the original license header.